Abstract:

Abstract:

Abstract:[Objective] We studied the effect of two diets on colonic microbial community structure and metabolites in Huanjiang mini-pigs. [Methods] Ten Huanjiang mini-pigs (initial bodyweight 33.5±8.1 kg) were randomly assigned into 2 groups with 5 pigs each, of which one group was fed with a diet with high-level nutrient (crude protein 13.11%, digestible energy 14.73 MJ/kg), and the other with low-level nutrient (crude protein 9.77%, digestible energy 12.24 MJ/kg). After 75 d, all animals were killed and the samples of colonic content were collected. Total bacterial DNA of three samples of pigs per group was extracted, and used to amplify PCR for 16S rRNA gene V4 tag fragment and sequence using high-throughput Miseq technique. Based on the QIIME platform, the microbial community diversity in colonic content was compared. The contents of short-chain fatty acid, ammonia, bioamine, indole, and skatole in colonic contents from five pigs per group were also analyzed using gas chromatography or liquid chromatography. [Results] Firmicutes, Bacteroidetes, Spirochaetes, and Tenericutes were the dominant phyla in colonic content of Huanjiang mini-pigs; dietary nutrient components did not affect the microbial community diversity in colonic content of Huanjiang mini-pigs. The relative abundance of Euryarchaeota was lower in colonic content of pigs fed diet with high-level nutrient, whereas Ruminococcus and Pseudobutyrivibrio were higher than those fed diet with the low-level nutrient. The contents of acetate and propionate were lower in colonic content of pigs fed diet with high-level nutrient, but ammonia and cadaverine were higher than those fed diet with the low-level nutrient. [Conclusion] Firmicutes, Bacteroidetes, Spirochaetes, and Tenericutes were the dominant phyla in colonic content of Huanjiang mini-pigs; diet with high-level nutrient in short feeding-period altered the contents of several colonic bacteria and their metabolic properties.

Abstract:

Abstract:[Objective] This study aimed to construct highly efficient recombinant Saccharomyces cerevisiae strain for cellulosic bioethanol production from Jerusalem artichoke stalk (JAS). [Methods] S. cerevisiae strain YB-2625 was selected as a host strain to construct xylose co-fermenting strain YB-2625 CCX, after which multicopies of xylitol dehydrogenase (XDH) encoding gene were integrated into the rDNA locus of YB-2625 CCX, and the most efficient strain named YB-73 was obtained. Finally, ethanol production from JAS was investigated by simultaneous saccharification and fermentation (SSF) using YB-73. [Results] YB-73 showed improved ethanol production by 13.9% compared with that of YB-2625 CCX and the xylitol yield of YB-73 was reduced to 0.31 g/g xylose from 0.89 g/g xylose by YB-2625 CCX when fermenting with 90 g/L glucose and 30 g/L xylose. Meanwhile, flocculation of YB-73 was observed in the presence of xylose, and the strain also showed high tolerance towards 5 g/L acetic acid and high temperature. The highest ethanol titer of 6.10% (v/v) was achieved from JAS in the process of SSF using YB-73. [Conclusion] Combination of host selection, introduction of xylose-consuming pathway and multi-copy overexpression of XDH in rDNA locus is a rational strategy to improve cellulosic bioethanol production performance of S. cerevisiae using JAS. This is the first report using recombinant S. cerevisiae to produce cellulosic ethanol from JAS.

Abstract:[Objective] This paper aimed to investigate the optimal fermentation of collagenase-producing conditions from Bacillus cereus R75E and obtain the high purity collagenase by protein separation and purification techniques. [Methods] We optimized the fermentation conditions and fermentation mediums for maximum production of collagenase from Bacillus cereus R75E using single factor experiment and orthogonal test. The collagenase-containing crude enzyme was obtained after centrifuging from the overnight fermentation of Bacillus cereus R75E. Then, the target collagenase was sequentially purified by ammonium sulfate precipitation, Butyl FF hydrophobic chromatography and SuperdexTM 200 gel filtration chromatography. Its purity was detected by SDS-PAGE electrophoresis. [Results] The optimal fermentation conditions and mediums for maximum production of collagenase from Bacillus cereus R75E were as follows: the fermentation temperature was 41 °C, the inoculation volume was 6%, the fermentation time was 36 h, the carbon source was 10 g/L glucose, the nitrogen source was 5 g/L peptone, and the initial pH was 7.0. The total crude enzyme activity was increased by 2.9 times compared with that of the non-optimized control. Finally, the target collagenase was purified with a purity of more than 90%. The purification fold and recovery of the target collagenase were reached to 18.4 and 1.1%, respectively. [Conclusion] We get the optimum collagenase producing conditions from Bacillus cereus R75E and construct a technological process for collagenase purification, which lay a foundation for the development and application of microbial collagenase.

Abstract:[Objective] Oligofructose is a promising food additive and health product. Enzymatically hydrolyzing the inulin by inulinase to produce oligofructoses was regarded as a promising, green and environment friendly technics. The aim of this study is to achieve an efficient production of Kluyveromyces marxianus inulinase and optimize the reaction parameters for oligofructose production from inulin. [Methods] The inulinase gene was cloned from K. marxianus strain CICC 1726 and expressed in Pichia pastoris cells. The reaction parameters such as pH, temperature, metal ions, substrate concentration and the amount of enzyme on the hydrolyzing of inulin to produce oligofructose were optimized. [Results] The inulinase activity of Pichia recombinants in 10 L fermenter reached 1 570 U/mL and the protein content in fermentation broth reached 2.75 g/L. In a 1 L reaction volume, when the parameters were pH 5.0, tempreture 50 °C, 0.2 mmol/L Mg2+ and 8% substrate, the inulin was properly hydrolyzed, with the content of C1 and C2 sugar was 9.25% and the oilgofructose (C3?C8) was 90.75% in the hydrolysates, among which the content of C3–C5 fraction was 72.92%. [Conclusion] This study has realized high-level heterologous expression of inulinase and facilitated the bulk preparation of oligofructose from inulin.

Abstract:[Objective] The purpose of the study was to analyze the actinobacterial diversity in the deep-sea sediments of the South China Sea by using culture-independent and culture-dependent approach. [Methods] Actinobacteria-specific 16S rRNA gene clone library was constructed. Representative clones selected based on the restriction fragment length polymorphism analysis were sequenced and placed into operational taxonomic unit (OTU) groups according to the 16S rRNA gene sequence similarity. Diversity statistics were analyzed using SPADE analysis software. Eight media were used to isolate actinobacteria strains from 11 sediment samples. 16S rRNA gene sequences of the representatives were sequenced to analyze phylogenetic diversity of the actinobacteria. [Results] Forty and ninety-nine positive clones were obtained from the two libraries and placed into 16 and 34 OTUs respectively. Both two libraries contained class Actinobacteria, Acidimicrobiia, Nitriliruptoria and Thermoleophilia. The dominant population of site N40-4 and N63-4 were order Streptomycetales and Nitriliruptorales respectively. Forty-one strains were obtained by the culture-dependent approach. Analysis of the 16S rRNA gene sequences of 19 representative strains showed that these strains belong to 10 different genera and 12 different species. [Conclusion] The deep-sea sediments of the South China Sea harbor abundant and diverse actinobacteria. The result also implied that there may be large numbers of unknown actinobacterial groups.

Abstract:[Objective] To investigate the biodiversity of marine fungi producing extracellular plasmin-like enzymes and plasminogen activators from the intertidal zone of Naozhou island and Xuwen coral reef nature reserve along Zhanjiang coast, and lay the foundation for discovery of new thrombolytics of plasmin-like enzymes and plasminogen activators. [Methods] Marine fungi were isolated and cultured by the method using potato dextrose agar (PDA) culture plates and yeast extract peptone dextrose (YPD) media, and identified by sequence analysis and phylogenetic tree construction of fungal rDNA internal transcribed spacer 1-5.8S rDNA-internal transcribed spacer 2 (ITS1-5.8S-ITS2) fragments. The marine fungi producing extracellular proteases were screening by the method using skim milk PDA (SM-PDA) plates, and the marine fungi producing extracellular plasmin-like enzymes and plasminogen activators were screening by the method using sea water fibrin PDA (FN-PDA) plates. [Results] A total of 446 strains of marine fungi were isolated, cultured and identified from the intertidal zone of Naozhou island and Xuwen coral reef nature reserve along Zhanjiang coast, which contained 98 species distributed in 65 genera, 46 families, 18 orders, 6 classes, belonged to Ascomycota and Basidiomycota of fungus. Amongst, there were 265 strains of marine fungi producing extracellular proteases represented 61 species distributed in 41 genera, 67 strains of fungi producing extracellular plasmin-like enzymes represented 22 species distributed in 14 genera, and 84 strains of fungi producing extracellular plasminogen activators represented 23 species distributed in 13 genera. The dominant genus was Aspergillus, and then Penicillium. [Conclusion] There were species biodiversity of the culturable marine fungi producing extracellular plasmin-like enzymes and plasminogen activators in the intertidal zone along Zhanjiang coast, which would be the rich resources for discovery of new thrombolytic agents.

Abstract:[Objective] Suaeda heteroptera Kitag which is a typical saline indicator plant has the function of restoring the saline-alkali soil polluted by heavy metals and oil. But little was known about the relationship between its root and endophytic microorganisms, microbial diversity and the function of rhizospheric microorganisms in bioremediation. In this study, we determined the diversity and structure of the endophytic and rhizospheric bacteria of Suaeda heteroptera Kitag from delta area in Panjin Liaoning Province. [Methods] The bacterial diversity in rhizosphere soil, root homogenate and root attachments of Suaeda heteroptera Kitag was analyzed by traditional culture methods and high-throughput sequencing. The selected strains were identified by morphological observation and analysis of 16S rRNA gene sequences and physio-biochemical characteristics. [Results] Sixty-seven strains were isolated from these three samples with traditonal methods, and twenty-eight strains among them were selected as the representative strains. The results showed that the strains were mainly affiliated with the genus Halomonas, Marinobacterium, Bacillus, Paracoccus, Pseudomonas, Planococlus, Serratia and Zhihengliuella. High-throughput sequencing analysis showed that these three samples with highest bacterial diversity were, in order, root attachments, rhizosphere soil and root homogenate. In total, twelve phyla were identified from these samples, which were Acidobacteria, Actinobacteria, Bacteroidetes, Chlorobi, Chloroflexi, Cyanobacteria, Firmicutes, Gemmatimonadetes, Planctomycetes, Proteobacteria, Spirochaetes and Verrucomicrobia. Bacteria assemblage was dominated by Cyanobacteria (42%) and Proteobacteria (33%) in root homogenate. Proteobacteria (46%) and Bacteroidetes (16%) were the predominant phyla in root attachments. Bacteroidetes (37%) and Proteobacteria (20%) were the predominant phyla in rhizosphere soil. [Conclusion] The diversity of endophytic and rhizospheric bacteria of Suaeda Heteroptera Kitag is high, which suggests that the bateria in this environment may play a role in the bioremediation of saline-alkali soil polluted by heavy metals and oil.

Abstract:[Objective] To study the diversity and antimicrobial activity of culturable actinobacteria from dried Jiuliancheng Nur in Hebei Province, China. [Methods] Actinobacteria were isolated by using dilution plating technique with 15 media. Isolates were analyzed by comparison of 16S rRNA gene sequences. Crude extracts from fermented broth were obtained using ethyl acetate and from mycelia by acetone. Disk diffusion was used in antibacterial and antifungal assay and positive strains were further screened for PKS I, PKS II and NRPS antibiotics biosynthetic genes by PCR. [Results] A total of 251 actinobacterial strains, isolated from 11 soil samples, belonged to 31 genera affiliated with 15 families in 10 orders; and Streptomyces and Nocardiopsis are dominant genera. Out of these isolates, 57 were halotolerant or halophilic isolates, including 22 Nocardiopsis isolates and 15 Nesterenkonia isolates. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain J11Y309 is a prospective novel genus affiliated with the family Glycomycetaceae and J12GA03 is a prospective novel member affiliated with the family Mycobacteriaceae. Out of 96 fermented strains, 56 exhibited positive activity in antibacterial or antifungal assay, and the total positive rate reached 58.3%. Out of 56 positive strains, 47 carried at least 1 antibiotic biosynthetic gene and 17 strains carried all the 3 genes. [Conclusion] Jiuliancheng Nur shows a rich biodiversity of culturable medicinal actinobacteria, and it is a valuable source of novel antibiotics.

Abstract:[Objective] Endoplasmic reticulum stress (ERS) activates a cytoprotective signaling cascade, termed as unfolded protein response (UPR). Recent advances have unveiled that UPR pathway was mainly mediated by Hac1p (transcription factor) and Ire1p (ERS sensor) in yeast. Our previous results suggest that protein-O-mannosyltransferase 1 (PMT1) deficiency enhanced the basal activity of UPR, and extended the replicative lifespan of yeast. In this study, we attempted to further study the effect of PMT1-deficiency on ERS response induced by tunicamycin in Saccharomyces cerevisiae. [Methods] Colony-forming ability of PMT1/IRE1 and PMT1/HAC1 double-gene deletion strains (pmt1Dire1D and pmt1Dhac1D) was analyzed under ERS condition. Cell proliferation assay was performed using the Microbial Viability Assay Kit. Expression levels of canonical UPR target genes were determined by quantitative RT-PCR (qRT-PCR). [Results] PMT1 deficiency strain (pmt1D) grew slowly under ERS condition, while both the IRE1- and HAC1- deletion strain (ire1D and hac1D) were not viable under this condition, compared to the control strain. The double-gene deletion strain (pmt1Dhac1D) exhibited enhanced growth ability under ERS condition, compared with the hac1D strain. Nonetheless, expression levels of UPR target genes showed no significant difference between pmt1Dhac1D and hac1D strains. [Conclusion] PMT1 deficiency enables hac1D strain to resist tunicamycin induced ERS, independent of the UPR activity.

Abstract:[Objective] A phage was isolated from Escherichia coli CICC 11021S fermentation media, and its biological characterization was studied. [Methods] A phage designated CICC 80003 was isolated using the double-layer agar culture method. Phage morphology was observed by transmission electron microscopy. Gel electrophoresis of phage genome was carried out after genome extraction and treatment by endonucleases. We investigated the optimal multiplicity of infection, one-step growth curve, pH and temperature stability, and host range. Additionally, we analyzed the effects of CICC 80003 on cell growth and L-aspartase activity of CICC 11021S. [Results] The phage plaque was round and transparent, and showed clear aureole. The phage had a regular head of 50?60 nm in diameter and a long tail with 120?130 nm in length. The phage genome could be cut by endonucleases BamH I and Mlu I. The optimal multiplicity of infection was 0.1. The one-step growth curve showed a latent period of 5 min and a rise period of 25 min. The average burst size was about 86 phage particles per infected cell. The optimal pH was 8.0. The phage was completely inactivated when incubated at 90 °C for 15 min. Some of Escherichia coli and Salmonella spp. strains could be split by CICC 80003. No cell growth and L-aspartase activity was detected when phage contamination occurred. [Conclusion] CICC 80003 was a dsDNA phage and belonged to the family Siphoviridae, which could completely split E. coli CICC 11021S in broth.

Abstract:[Objective] The experiment was designed to screen bacteria that could tolerate phlorizin and then study the diversity and composition of microbial community of phlorizin-resistant bacteria, which were isolated from the rhizosphere of Malus baccata in different years. Through the study, we aimed to find the potential efficient phlorizin-degrading strains and provide a scientific basis for understanding of the mechanism of continuous cropping obstacles in apple and to overcome or reduce the losses caused by it. [Methods] The phlorizin-resistant bacteria were isolated from five different years’ soils using phlorizin as the sole carbon source. The amplified rDNA restriction analysis (ARDRA) and 16S rRNA gene sequences and phylogeny analysis were employed to identify taxonomic status of phlorizin-resistant bacteria, while the distribution and diversity of the microbial community and its relationship with the physicochemical parameters were analyzed by bioinformatics analysis. [Results] A total of 103 distinct bacterial strains belonging to 13 genera were obtained from apple rhizosphere soil and they could be divided into 18 groups at 65% similarity. Bacillus, Pseudomonas and Novosphingobium were dominant genera. The result showed that rhizosphere soil which was continuously planted for 3 years had the highest diversity and the community composition of phlorizin-resistant bacteria was similar for those continuously planted for 15, 20, 25 years. Pearson analysis exhibited phlorizin-resistant bacteria had a certain correlation with the physicochemical parameters (P<0.05). The redundancy analysis (RDA) also indicated that ferulic acid was an important factor affecting phlorizin-resistant bacterial community structure. [Conclusion] The genetic diversity of phlorizin-resistant bacteria was abundant, and correlations were revealed between the phlorizin-resistant bacteria community structure and soil physicochemical factors. Ferulic acid was an important factor that could influence the community structure of phlorizin-resistant bacteria. This study provides some useful information for alleviating apple continuous cropping obstacles to some extent.

Abstract:[Objective] The purpose of this study is to isolate and identify antagonistic myxobacteria against Phytophthora infestans from soil samples collected from a farmland near the Yellow River and analyze the stability of the fermentation supernatant of the antagonistic strain and the inhibition effect on the pathogen of potato late blight preliminarily. These findings may lay a foundation for the isolation and identification of the antibiotic substances and the development of new biological pesticides resistant to potato late blight. [Methods] The strain was isolated by the rabbit dung baiting method. The antagonistic strains were screened by plate confrontation assay and identified by its morphological, physiological, and biochemical characteristics, and its 16S rRNA gene sequence. The growth curve of strain YR-7 was tested by a weighing method. Inhibitory rate of the fermented supernatant at different stages on the mycelial growth of P. infestans and stability of the fermented supernatant was tested by a plating method. Effect of the fermented supernatant of strain YR-7 on disease prevention for detached potato leaves was evaluated by spraying concentrated fermentation supernatant on the detached potato leaves. [Results] Seven strains of myxobacteria were isolated and four of them presented antagonistic activity against P. infestans. The strain YR-7 with the strongest antagonistic activity showed an inhibition rate of 96% to P. infestans and was identified as Myxococcus xanthus. After the strain YR-7 was cultured for 7 days, inhibitory effect of its fermented supernatant on the mycelial growth of P. infestans tended to be stable. Its activity could be maintained from 30 °C to 50 °C (inhibition rate of 50.90%) and decreased when the temperature exceeded 50 °C. Its activity still remained an inhibition rate of 25.45% after treated at 90 °C for 1 h. The concentrated fermentation supernatant was stable from pH 4.0 to 9.0 and its inhibition rate was more than 40.21%. Its activity significantly decreased when the pH value was less than 4.0 or greater than 9.0. The active substances could not be degraded by protease and their activity was not affected by UV and natural light exposure. The relative lesion area of potato leaves declined from 68.19% to 0.35% when the concentrated fermentation supernatant was sprayed on the leaves before the spore suspension of P. infestans was inoculated. [Conclusion] The strain YR-7 can produce secondary metabolites against the pathogen of potato late blight. The antibiotic substances have good stability and could effectively inhibit P. infestans from infecting potato leaves, which have the potential value for developing biological pesticides resistant to potato late blight.

Abstract:[Objective] Strain CICC 10774 causing vinegar spoilage was identified by polyphasic taxonomy and its growth and metabolism properties were studied. [Methods] Strain CICC 10774 was identified by 16S rRNA gene sequences phylogenetic analysis combined with morphology and physiological and biochemical characteristics. The optimal temperature and pH value for growth were measured using spectrophotometric method and the metabolic products were analyzed by HPLC. [Results] Polyphasic taxonomy analyses revealed that strain CICC 10774 was identified as Lactobacillus acetotolerans. The strain was Gram-positive, facultative aerobic, positive for gelatinase activities and could use mannose, N-acetylglucosamine, arbutin, esculin, salicin, cellobiose, trehalose and gentiobiose as sole carbon sources for growth. The optimal growth was observed at 37 °C and pH 5.0, and major metabolic products were acetic acid and lactic acid, indicating that strain CICC 10774 was a typical acidophilic bacterium. [Conclusion] The growth and metabolism properties of Lactobacillus acetotolerans CICC 10774 causing vinegar spoilage were studied to provide a theoretical basis for the vinegar production enterprises to control microbial pollution.

Abstract:[Objective] A continuous high mortality of Carassius auratus gibelio occurred in a farm of Yangzhou area in Jiangsu Province. [Methods] A purely cultured strain (YZ-1) isolated from liver of sick Carassius auratus gibelio, and its main morphological physiological and biochemical characteristics were examined. [Results] For further confirmation on molecular level, 16S rRNA gene was sequenced; and the accession number in GenBank is JX164202 in length of 1 446 bp. Sequences analysis on the 16S rRNA gene shows that it is very similar to other Aeromonas salmonicida, and their nucleotide homology was between 99% to 100%. Its phylogenetic tree showed that the pathogen isolated from the diseased C. auratus gibelio was identified as Aeromonas salmonicida subup. salmonicida isolate. The challenge test using YZ-1 displayed that the prevalence of symptoms and spontaneous onset symptoms were the same. The antibiotic sensitivity using 44 antimicrobial agents showed that the isolate was sensitive to 23 agents, including cefuroxime, cotrimoxazole, enrofloxacin, and cephradine; sensitive slightly to 11 agents, including amikacin, tetracycline, norfloxacin, spectinomycin, and cefradine; and resistant to 10 agents, including peillin G, streptomycin, gentamicin, florfenicol, and vancomycin. [Conclusion] The death of Carassius auratus gibelio is caused by Aeromonas salmonicida subup. salmonicida.

Abstract:[Objective] This study aimed to construct a genetically engineered Saccharomyces cerevisiae strain for inositol production by overexpressing its INO1 gene that encodes inositol-1-phosphate synthase. [Methods] The integrated multi-copy expression vector pURIH was constructed via an rDNA-mediated method and transformed into S. cerevisiae Y01 strain. The expression levels of INO1 in genetically engineered strains were analyzed through quantitative RT-PCR. was detected through HPLC. [Results] Two genetically engineered strains, namely, YI2-1 and YI2-2, were constructed. These strains could highly express INO1. YI2-1 produced 16.235 times more inositol than Y01 did. The KanMX resistance gene was knocked out in the YI2-1ΔKP strain, which efficiently produced up to 627 mg/L inositol. [Conclusion] pURIH could be applied to overexpress homologous INO1 in S. cerevisiae. The amount of inositol produced by the engineered strain was sufficient and thus could be employed in engineering applications.

Abstract:[Objective] In order to predict the function of MSMEG_6281 in Mycobacterium smegmatis mc2155, we analyzed the effect of overexpression of MSMEG_6281 on cellular growth and morphological characteristics. [Methods] Ethambutol, one of the first anti-tuberculosis drugs, can destroy structure of cell wall of mc2155 and cause the changes of cellular morphology. The expression change of MSMEG_6281 is determined after ethambutol treatment by RT-PCR. The intact MSMEG_6281 gene was amplified from M. smegmatis mc2155 genomic DNA . After analyzing by enzymatic digestion and DNA sequencing, the MSMEG_6281 gene was cloned into vector pVV16 to constitute the recombinant plasmid of pVV16-MSMEG_6281. The expression of MSMEG_6281 for the recombinant mc2155 strain was confirmed by SDS-PAGE and western blotting. [Results] RT-PCR results show that gene expression of MSMEG_6281 was up-regulated under the condition of ethambutol treatment for 6 h and 12 h. The recombinant mc2155 strain over-expressing MSMEG_6281 demonstrated a lag growth, and the cellular morphological turns longer than wild type mc2155. [Conclusion] MSMEG_6281 must be related with peptidoglycan metabolism of the cell wall.

Abstract:Coccolithophores are one of the most widespread groups of unicellular eukaryotic marine phytoplankton and play crucial roles in marine ecosystem. Some coccolithophores are bloom-forming species in ocean and offshore. In natural marine ecosystem, virus infection is one of the major causes of natural mortality and the demise of large oceanic blooms formed by this group. Integrated analysis based on the genomic sequences of Emiliania huxleyi, a major species of coccolithophores and its specific lytic virus Emilliania huxleyi virus (EhV), has implied that EhV obtained a series of key enzyme genes involved in sphingolipids metabolism from host genome by horizontal gene transfer. In some ways, EhV manipulates sphingolipids metabolism of host and triggers biosynthesis and accumulation of infection-derived sphingolipids, resulting in the apoptosis of host cell. Thus, virus-mediated host sphingolipids metabolism plays an important role in virus-host interaction. Here, we describe the horizontal gene transfer between EhV and host, the characteristics of virus-mediated host sphingolipids metabolism and the ecological significance in order to understand the complicated interaction between E. huxleyi virus and its host.

Abstract:Microbial biochemical oxygen demand (BOD) sensor is a kind of equipment for rapid detection of organic pollutants in water samples. The immobilized microorganisms is the heart of a microbial BOD sensor, which has great influence on the performances of the sensor like stability, response time, service life, linear response range as well as the practical apply range. Biofilm-type BOD sensors were widely studied and applied for their advantages such as simple structure, high sensitivity and short response time compared with other types of microbial BOD sensors. This article provides an overview on the application of immobilized microbes in biofilm-type BOD sensors. The principles, properties and applications of typical immobilization methods were summarized. Particularly, a range of frequently-used and potential immobilizing carriers were detailed. The relationships between characteristics of the carriers and the performances of sensors were analyzed, the microorganisms applied in this field were reviewed. Furthermore, the application and commercialization of biofilm-type BOD sensors were introduced, the pros and cons of varies types microbial BOD sensors were compared. Finally, unsolved problems of immobilized microbes in biofilm-type BOD sensors and its trend of development were discussed.

Abstract:Bacteria affiliated with the genus Acinetobacter distribute widely in the natural environment. By emulsifying and degrading hydrocarbons, bacteria in this genus play great roles in biodegrading of hydrocarbons. In this review, we summarized the research progress in biodegradation of petroleum hydrocarbons by Acinetobacter spp. We also discussed known alkane and aromatic oxidases. Different types of surfactant produced by bacteria in the genus Acinetobacter and their emulsifying mechanisms were concluded. Immobilization of functional bacteria and their potential use were mentioned. Biodegradation of hydrocarbons using bacteria in field were prospected in this review.

Abstract:The use and control of microbial adhesion in environmental area have been received greater attention from researchers. Microbial cell surface free energy, as one of cell surface properties, has important influence on adhesion behavior of microorganisms. This article highlights the role of surface free energy on microbial adhesion through thermodynamic approach, Derjaguin-Landau-Verwey- Overbeek (DLVO) theory and extended DLVO (XDLVO). Based on these theories, the characterization method of microbial surface free energy calculated from contact angle and its influencing factors are introduced. Besides, it analyses the distribution feature of microbial surface free energy, its components and its relationship with substances composition. Finally, this review summarizes the application of surface free energy in environmental microorganisms’ adhesion, including adhesion on solid substrates, liquid substrates and adhesion between microorganisms according to adhesion substrates. Feature research should pay more attention to the standard characterization method of environmental microorganisms’ surface free energy and its application in complex circumstances.

Abstract:To find novel antimicrobial agents are becoming more and more important, since microbial pathogens have increased the resistance to antibiotic. One of reasonable factors is bacteria decreased the membrane permeability to drugs. Siderophore is a small molecular compound secreted by bacteria. After chelating iron, the Siderophore complex was bound by specific outer membrane receptor and transported into the cell. Similarly, the synthesized Siderophore-antibiotic conjugates can be recognized by bacteria and transported into the cell. As soon as the conjugates was transported into the cell, the antibiotic was released and killed the bacteria. Moreover, the conjugates also can prevent the bacteria get more iron. In this paper, we described the research progress of Siderophore-antibiotic conjugates as a novel antimicrobial agents. It will provide a theoretical basis for development of new antimicrobial agents and can help treat disease caused by antibiotic resistant disease.

Abstract:With the increasing concentration of the hydrophobic organic pollutants (HOPs) in the environment, it is important to obtain the highly efficient HOPs-degrading bacteria. In recent years, the researches on improving HOPs microbial degradation using two-phase system have made some progresses. In this paper, the structure characteristics of two-phase systems, their enrichment principles for HOPs-degrading microorganisms, and main influencing factors, as well as their applications were reviewed. Additionally, the main challenges and new perspectives on accelerating the biodegradation and detoxification of toxic HOPs using the two-phase system were discussed.

Abstract:The present problems in the cultivation pattern of professional talents of edible fungi was analyzed from the guidance of course teaching content, time lag of course design, lack of training teaching and passivity of teaching method to attain the train objective of professional talents with high quality for edible fungi industry. Taking South China Agricultural University for example, the cultivation pattern of professional talents in edible fungus industry was explored from the cognitive concept and characteristic feature of edible fungi industry, setting up and optimization of the theory and practice content, teaching methods and means and testing methods. The study could provide reference for further improving the existing personnel cultivation programs and promoting the reform of personnel cultivation pattern.

Abstract:[Objective] To develop an LAMP-LFD method to detect rapidly Shigella spp., based on nucleotide enrichment by a loop-mediated isothermal amplification (LAMP) and chromatographic visualization by a lateral flow dipstick assay. [Methods] Three pairs of primers were designed based on conserved regions of the invasive plasmid antigen H (ipaH) gene of Shigella flexneri and used in LAMP reaction, among which the forward inner primer Sfl-ipaH-FIP was biotinylated. Similarly, a fluorescein isothiocyanate (FITC)-labeled probe Sfl-ipaH-HP was designed to specifically hybridize with LAMP products. And the hybridized products were visually detected by LFD. [Results] The LAMP-LFD method to detect Shigella spp. was developed. The optimized condition for LAMP reaction was at 63 °C for 40 min; and plus visually detecting by LFD, it was approximately 50 min. The LAMP-LFD method discriminated S. flexneri from another 4 pathogenic bacteria causing diarrhea (Salmonella enteric, Campylobacter jejuni, Yersinia enterocolitica, and Vibrio cholera) and 5 common food-borne pathogens (V. parahaemolyticus, V. vulnificus, Listeria monocytogenes, Staphylococcus aureus, and V. alginolyticus), and 4 different Escherichia coli strains. The detection limit of LAMP-LFD was 1.0×102 CFU/mL for Shigella pure cultures (equivalent to 4 CFU per reaction), which was 100 times lower than that of the conventional PCR method using primers Sfl-ipaH-F3/Sfl-ipaH-B3. In the case of artificially contaminated Common carp intestinal tissue, the detection limit was 5×102 CFU/mL (equivalent to 20 CFU per reaction). [Conclusion] This rapid and accurate LAMP-LFD method is a promising alternative in the routine surveillance and point-of-care test of Shigella spp.

Abstract:[Objective] Due to the difficulties in preserving demethylvancomycin producing strain, we optimized the preservation conditions, and assessed the 10-year stability of different preservation methods with liquid nitrogen preservation, ?80 °C cryopreservation and lyophilization outcomes. [Methods] Using glycerol and skim milk as the basic protective agent for cryopreservation and lyophilization, the effect of cooling rate for liquid nitrogen cryopreservation and impermeability protective agents such as trehalose and polyvinylpyrrolidone (PVP) to these three preservation methods were studied. Ten years tracking assessment on optimal preservation method was performed. [Results] Among the three preservation methods, ?80 °C cryopreservation showed the highest survival rate for demethylvancomycin producing strain, followed by liquid nitrogen cryopreservation and lyophilization. The optimum cooling rate for liquid nitrogen cryopreservation was rapid freezing, and the optimum protective agent was as follows: 8.0% glycerol with 3.5% trehalose for liquid nitrogen cryopreservation, 6.0% glycerol with 5.0% PVP for ?80 °C cryopreservation, skimmed milk with 6.0% trehalose for lyophilization. The 10-year survival rate of liquid nitrogen preservation reached 70.6% through optimum preservation condition, productivity of demethylvancomycin remained 92.9% of the original level. [Conclusion] Under optimum preservation condition, liquid nitrogen cryopreservation is suitable for long-term preservation.

Abstract:[Objective] To investigate the effects of common organic solvents of dimethyl sulfoxide (DMSO), acetone and ethanol on the activities of bacteria for guiding the selection of solvent and addition of its dosage in the antibacterial test in vitro. [Methods] Consulting the results of growth curve method, conventional antibacterial tests (disk diffusion method and broth dilution method) were used to determine inhibitory effects of DMSO, acetone and ethanol on the bacterial strains of Escherichia coli and Staphylococcus aureus. The changes of cell morphology after treated by these solvents were studied by scanning electron microscope (SEM). [Results] When the solvent inhibitory effects on E. coli and S. aureus were 20%, the concentration (V/V) of solvent DMSO, acetone, ethanol were 1.00%, 0.25%, 2.00% and 1.00%, 1.00%, 0.50% in the broth dilution method, respectively. For the growth curve method, the concentration (V/V) of DMSO, acetone, ethanol were 0.50%, 1.00%, 0.50% and 1.00%, 0.50%, 0.50% when 20% inhibitory effects on E. coli and S. aureus were reached, respectively. 32% (V/V) DMSO and 32% (V/V) ethanol showed obvious inhibitory rings for E. coli, but no inhibitory rings appeared for S. aureus in the same concentrations of studied solvents with disk diffusion method. To compare three methods, the inhibitory effects of DMSO, acetone and ethanol were 20% while their concentrations (V/V) all were lower than 0.5%; under this condition, effects on the viability of bacteria were slight. SEM showed that limited solvent concentrations could decrease their effects on the growth of E. coli. [Conclusion] To compare with DMSO and acetone, ethanol showed a stronger effect on growth and reproduction of microorganisms. After treated with the same concentration of medicinal solvent, liquid testing condition, such as broth dilution method and growth curve method, induced the stronger effect on the cells.