Abstract:[Background] Optically pure L-phenyllactic acid (L-PLA) is a natural antimicrobial agent and also a highly value-added chiral compound with potential applications in food, pharmaceutical and biomaterial areas. Although L-PLA can be produced by asymmetric reduction of phenylpyruvic acid (PPA) by L-LcLDH, an L-lactate dehydrogenase from Lactobacillus casei CICIM B1192, it displays low activity. To improve the activity of a wild-type L-LcLDH towards PPA, an L-LcLDH mutant, L-LcLDHQ88R, was successfully constructed by our lab. Its catalytic efficiency (kcat/Km) was 4.9-fold higher than that of L-LcLDH. [Objective] To further improve the catalytic efficiency of L-LcLDHQ88R towards PPA, the amino acid Ile229 located in the substrate-binding pocket of L-LcLDHQ88R or L-LcLDH was randomly substituted with any one of 20 amino acids. [Methods] Using a recombinant plasmid pET-22b-LcldhQ88R as the template, the Ile229-encoding codon in LcldhQ88R was subjected to site-saturated mutagenesis by whole-plasmid PCR technique. Then, the mutant library of L-LcLDHQ88R was constructed by transforming pET-22b-LcldhQ88R variants into E. coli BL21(DE3), respectively. Finally, an E. coli transformant expressing the highest activity towards PPA was screened from this library. [Results] The selected transformant, E. coli/LcldhQ88R/I229Q, contains a double-mutant gene in which the Gln88- and Ile229-encoding codons in Lcldh was substituted with Arg- and Gln-encoding ones, respectively. The specific activity of purified L-LcLDHQ88R/I229Q towards PPA was 18.5- and 2.3-fold those of L-LcLDH and L-LcLDHQ88R, while its catalytic efficiency was 6.8- and 1.4-folds those of the latter two, respectively. Additionally, the pH and temperature properties of L-LcLDHQ88R/I229Q did not obviously changes compared to L-LcLDH. The analysis of catalytic mechanism by molecular docking (MD) simulation showed that the double-mutation of Q88R/I229Q enlarges the inlet of substrate-binding pocket and alters the steric structure of active centre, which may contribute to the increase of activity. [Conclusion] The double-mutation of Q88R/I229Q in L-LcLDH primary structure greatly enhanced its specific activity and catalytic efficiency, making L-LcLDHQ88R/I229Q a promising candidate for asymmetric reduction of PPA.

Abstract:[Background] The mechanisms of solubilizing-phosphorus by organisms are diverse, which significantly stimulates plant growths. [Objective] To characterize a phosphorus-solubilizing alkaline phosphatase from Bacillus amyloliquefaciens YP6. [Methods] An alkaline phosphatase, AP3, of YP6 was cloned, expressed in Escherichia coli BL21(DE3), characterized and its phosphorus-solubilizing effect tested. [Results] AP3 was an alkaline phosphatase, with optimal pH at 10.3 and optimal temperature at 40 °C. Vm was 4 033.4 μmol/(min·mg) and Km was 12.2 mmol/L. The soluble phosphate of rock phosphorus was enhanced obviously by enzyme AP3 treatment for 24 h, and by inoculation of the strain Bacillus amyloliquefaciens YP6 for 7 days. [Conclusion] Alkaline phosphatase AP3 can be used as a phosphorus-solubilizing enzyme.

Abstract:[Background] Source of radiation-resistant microorganisms is rich in Chinese radiation-polluted area in Northwest China, where some places are covered with Kalidium foliatum (Pall.) Moq. Salt accumulation constructed a salt island in the rhizosphere of Kalidium foliatum. Therefore, it will be important to collect the microbial resources and to reveal the mechanism of salt adaptability and salt island formation for Kalidium foliatum. [Objective] We analyzed the bacterial composition in the rhizosphere of Kalidium foliatum from the radiation-polluted area, and investigated the microbial resources and their functional properties. [Methods] Based on traditional culture methods, rhizosphere microorganisms were isolated using 10 culture media, and identified by 16S rRNA gene sequence analysis. Then characteristics of the resistance, enzyme producing and plant growth promoting were tested. [Results] A total of 267 isolates were obtained, and classified into 20 genera from Actinobacteria, Proteobacteria and Firmicutes. Isolates from Actinobacteria were dominant component involving 9 genera. Eight potential novel species were discovered. Bacterial diversity was rich in the rhizosphere of Kalidium foliatum. The resistance analysis of strains showed that more than 70% of the representatives could tolerant 10% NaCl, and 40% of them were resistant to different heavy metal ion. At the same time, several isolates producing protease, lipase, amylase and cellulase were observed, and some plant growth promoting bacteria were obtained, which provide important material to further screening industrial enzyme and developing microbial fertilizer. [Conclusion] Valuable microbial resources existed in the rhizosphere of Kalidium foliatum.

Abstract:[Background] Seeds can harbor a lot of microorganisms and may influence a range of seed traits. The interactions between seed type and microorganisms are important for understanding seed germination and seedling growth. However, the interaction between different type seeds and seed-associated microorganisms in seed-heteromorphic plant is poor characterized. [Objective] To isolate and analyze community composition and growth-promoting activities of the epiphytic bacteria of two distinct types of fruits present on the same plant, Suaeda glauca Bunge., which mainly distributed in saline-alkaline soil. [Methods] Conventional culture dependent method was used to isolate the epiphytic bacteria from dimorphic fruits of S. glauca. The identification of the isolated strains was done based on 16S rRNA gene sequencing. The growth-promoting activities of isolated strains were also analyzed qualitatively. [Results] The epiphytic bacterial community composition of the type A fruits clearly differed from those of type B fruits. The results showed that, 67 epiphytic bacteria were isolated from type A fruits, which belonged to 3 classes, and 15 genus with Curtobacterium (34.33%), Bacillus (13.43%) and Pantoea (10.45%) as the most dominant genus; whereas 47 epiphytic bacteria were isolated from type B fruits, which belonged to 4 classes, 20 genus with Curtobacterium (12.77%), Bacillus (17.02%) and Frigoribacterium (14.89%) as the most dominant genus. The diversity of isolates were analyzed and compared using different diversity index, the shannon index, margalef index and evenness index which showed type A fruits were lower than those of type B fruits; but the Berger-Parker dominance index of type A fruits was higher than that of type B fruits. The percentage of the isolates with nitrogen-fixing, phosphate-solubilizing, potassium-dissolving, siderophore-producing and IAA-producing activity showed different changing trend in the dimorphic fruits of S. glauca. The high-proportioned nitrogen-fixing activity and the low-proportioned phosphate-solubilizing activity presented in strains which isolated from the type A and type B fruits of S. glauca. In addition, the percentage of potassium-dissolving activity in strains isolated from type A fruits showed higher than that of type B fruits, whilethe IAA-producing activity in strains isolated from type A fruits showed lower than that of type B fruits. [Conclusion] Our results show thatthe diversity, the community composition and growth-promoting activities of epiphytic bacterial communities in the dimorphic fruits of S. glauca arevaries.

Abstract:[Background] Plastic are synthetic polymers derived from fossil oil and largely resistant to degradation. Plastic litter have adverse effects on the environment and marine biota. Therefore, new solutions for petroleum-based plastic waste degradation are urgently needed. [Objective] Polystyrene (PS) is notoriously persistent plastic that is not degradable at appreciable rates for decades. However, an environment was identified in which PS is susceptible to biodegradation: yellow mealworm, the larvae of Tenebrio molitor Linnaeus, can damage PS packing by chewing and eating styrofoam. So we try to isolate PS-degrading microorganisms from the mealworms’ gut. [Methods] The larvae fed with styrofoam as the sole diet could live as well as those fed with bran diet over several months. Based on morphological, physiological and biochemical properties as well as 16S rRNA gene and ITS gene sequences analysis, the phylogenic tree was constructed to identify the taxonomic status of the strains. [Results] Two bacterial strains capable of degrading styrofoam were isolated from worm fecula egested from styrofoam-feeding larvae, named as Bacillus anthracis PSI-1 and Enterobacter hormaechei PSI-2. A PS-degrading fungal strain was isolated from the gut of mealworms and identified as Aspergillus niger KHJ-1. Over a 14-day incubation period of the fungal train KHJ-1 on PS films, a large number of cavities were obviously observed on PS films surfaces, and the changes were measured about the film of mechanical properties. The results showed that hydrophobicity of the film was decreased dramatically, the elongation at break and the tensile strength became smaller. A suspension culture of KHJ-1 strain was able to degrade 214.8 mg/5 g of PS solid particles, the weight loss ratio of PS was 4.29% over a 60-day incubation period. [Conclusion] The results demonstrated the presence of PS-degrading bacteria and fungus in the guts of mealworms could degrade PS directly and efficiently and provided promising evidence for the biodegradation of PS in the environment.

Abstract:[Background] Phenolic wastewater is toxic, widespread and difficult to be decomposed. Biological treatment of phenolic wastewater has a broad application prospects due to its low cost and no secondary pollution. In the microorganisms that can degrade phenol, the fungi are more adaptable to the harsh environment than the bacteria. For the bottlenecks such as the short storage time of the fungal suspension and the difficulties for transport, preparation of microbial inoculum can improve cell viability and storage stability. [Objective] This paper tried to isolate an efficient phenol-degrading fungi, optimize the degradation performance and select the appropriate carrier for the preparation of its microbial inoculum. [Methods] Step-by-step domestication and purification was used to isolate the efficient phenol-degrading fungi. The species identification was carried out by ITS rDNA gene sequence analysis. The phenol degradation performance was further optimized by single factor experiments. Four different materials was used as carriers for the preparation of the microbial inoculum, then investigation of its preservation effect at different temperatures by dilution-plate method and phenol degradation were tested. [Results] An efficient phenol-degrading fungi named QWD1 was isolated and the identification proved it belonged to the Magnusiomyces capitatus genus. The optimal degradation conditions were as follows: (NH4)2SO4 as nitrogen source, inoculum concentration 15%, pH 7.0, temperature 35 °C, nitrogen source concentration 14 mmol/L. Under this condition, the removal rate of phenol was up to 97.15% in 28 hours. The optimum carrier for the preparation of the fungi was cavings, the storage temperature was 4 °C and the storage time can reach 90 days or even longer. The number of viable fungi was about 2.5×108 cfu/g, and the effect of phenol-degrading was good. [Conclusion] A high-efficiency phenol-degrading fungi was screened, for which the degradation performance was optimized, and it was prepared as the microbial inoculum, which provided new strain and theoretical support for the treatment of phenolic wastewater.

Abstract:[Background] Alcohol affects people’s health in two ways: beneficial or harmful. Influence of alcohol on the intestinal micro-ecological system is great. [Objective] Present study was to explore the influence of alcohol intake on blood, intestinal microbiota and enzyme activities of mice. [Methods] SPF (specific pathogen free) experimental mice were randomly divided into 4 groups: control group, low dose group, medium dose group and high dose group. Mice of the control group were given sterile water to drink, other groups were given 10%, 20% and 30% (v/v) ethanol solution respectively to drink freely for 1 month. Then the mice were sacrificed, enzyme activities and microorganisms in mice intestinal contents were analyzed. Blood was collected by the eyeball method and analyzed at the same time. [Results] Compared to the control group, the amounts of lactobacillus in mice intestine of the low dose group increased significantly (P<0.05). However, the numbers of colibacillus and bacterium decreased evidently (P<0.01 or P<0.05). The amounts of lactobacillus and bifidobacteria reduced sharply (P<0.01). Compared to the low dose group and medium dose group, the activities of xylanase, protease and amylase in mice intestine of the high dose group increased obviously (P<0.01). The activities of the digestive enzymes in mice intestine of the low dose group was lower than that of the control group. Hematocrit in mice of the low dose group was lower than the control group (P<0.05). [Conclusion] Our findings suggested that high alcohol consumption induced the decrease in the number of intestinal probiotics and intestinal barrier function, but low alcohol consumption can regulate the intestinal flora and enzyme activities in mice intestine.

Abstract:[Background] Intestinal microbiota is related to several physiological functions of human body. A large number of studies have shown that Qiweibaizhu powder has effects on diarrhea mice. [Objective] Compare with traditional Chinese medicine and ultra-shattered medicine curative effect. To explore the correlation efficacy with Qiweibaizhu powder to provide scientific evidence for the clinical application. [Methods] Dysbacteriotic diarrheal mice model were constructed via administration of antibiotics and then treated with traditional Qiweibaizhu powder and 50% amount of ultra-shattered Qiweibaizhu powder. After the treatment, 16S rRNA gene of microorganisms in intestinal contents of different groups was analyzed by PCR cloning, and corresponding gene library was constructed. [Results] Lactobacillus spp., Enterococcus feacium, Clostridium spp., Blautia producta, Anaerostipes spp., Staphylococcus saprophyticus and uncultured bacterium were in the normal intestinal microbial flora, and Lactobacillus spp. was the dominant bacteria in the predominant intestinal microbial flora, accounting for 61.90% of the total bacterial DNA clone number. Compared with the control group, the proportion of Lactobacillus spp. in the model group was significantly decreased and opportunistic pathogen was increased. After intrgastric administration, the proportion of Lactobacillus spp. in the traditional Qiweibaizhu powder treatment group and 50% amount of ultra-shattered Qiweibaizhu powder treatment group was recovered, which the proportion of Lactobacillus spp. in 50% amount of ultra-shattered Qiweibaizhu powder treatment group was close to the normal group. Through establishing a clustering tree and calculating the diversity (H), species richness (S) and dominance index (D) of each category, we knew that each index of 50% amount of ultra-shattered Qiweibaizhu powder treatment group were approximately to the control group. In conclusion, the intestine microbial diversity of 50% amount of ultra-shattered Qiweibaizhu powder treatment group was most close to the normal group. [Conclusion] The 16S rRNA gene clone library technique was used to further clarify the composition of bacterial community in normal mice and the recovery of intestinal bacterial community in Qiweibaizhu powder, and the effect of 50% amount of ultra-shattered Qiweibaizhu powder treatment was better than the traditional Qiweibaizhu powder treatment.

Abstract:[Background] Many endophytic diazotrophs can be found in gramineous plants and play important roles in promoting plant growth, nutrient utilization and stress resistances. [Objective] This research aims to reveal the composition and variation of endophytic diazotrophs in roots, stems and leaves of Pennisetum sp. at different developmental stages. [Methods] High-throughput sequencing technology was used to analyze the endophytic diazotrophs flora in roots, stems and leaves at different growth stages of Pennisetum sp. [Results] About 40 000 to 60 000 useful sequences were obtained from 15 samples in the roots, stems and leaves of Pennisetum sp. at different growth stages, and were mainly distributed within about 360 bp. At maturity period, the abundance of endophytic diazotrophs from the root of Pennisetum sp. was the highest whereas at jointing period, the stem and leaf samples showed the highest abundance. In the same growth period, the trend in abundances was observed thus: root > leaf > stem. This trend of variation was consistent with the trend of nitrogenase activity in plant samples of Pennisetum sp. The major bacterial communities identified belong to the Proteobacteria, Cyanobacteria and Klebsiella, Herbaspirillum, Bradyrhizobium. As a whole, the composition of the microbial community present in root and leaf samples was similar, whereas that from the stems had a cross with the roots and leaves. At maturity period, the abundance of associated nitrogen-fixing bacteria was highest in the roots. CCA analysis showed that the endophytic diazotrophs from different samples were mainly affected by environmental temperature, followed by moisture and pH. [Conclusion] There were great differences in composition and abundance of endophytic diazotrophs from roots, stems and leaves at different growth stages of Pennisetum sp. Our findings provide important information for development and utilization of endophytic diazotrophs resources from Pennisetum sp.

Abstract:[Background] Phytophthora root rot as a devastating soybean disease has been reported in the United States, Canada and many other countries, its pathogen Phytophthora sojae is a typical soil-borne pathogen. In recent years, the interaction between soil-borne pathogens and plant roots has become the main direction for studying the host selectivity mechanism of soil-borne pathogens. [Objective] To study the effects of Phytophthora sojae zoospores to the rootlet and root exudates of host soybean and non-host common bean, illustrate the relationship between these effects and P. sojae selecting its host. [Methods] The soybean susceptible cultivar Sloan and resistant cultivar Williams82 as well as non-host common bean Yidianhong of P. sojae were cultivated by the method of situ soil culture. The pre-infection behavior of the single zoospore of P. sojae to the rootlet of host soybean and non-host common bean was determined. The root exudates of host soybean and non-host common bean were collected and the chemotaxis of P. sojae zoospores to the root exudates was measured, including taxis of the zoospores to the root exudates, the promotion of the root exudates on the zoospores encystment, and on the germination and the growth of the germ tubes. [Results] The single zoospore had strong chemotaxis to the host rootlet. It encysted and germinated rapidly on the elongation zone of the root tip after several exploratory contacts along the root surface. The tip of the germ tube attached to the rootlet surface. The difference between the susceptible and resistant cultivar was that the germ tube on the rootlet of susceptible cultivar is shorter and thicker. However, the single zoospore had no chemotaxis to the rootlet of non-host common bean rootlet. It ran away from the rootlet after first visit of the rootlet surface, then encysted and germinated in a random growth direction at the location of approximately 75 μm far away from the rootlet. The substantial difference in the behavior which the P. sojae zoospores infected the rootlet of host soybean and non-host common bean had been repeated in the experiments with root exudates, that is P. sojae zoospores had strong chemotaxis to host root exudates. The host root exudates could effectively attract zoospores and promote encystment of the zoospores and germination of cysts, but inhibit the growth of the germ tube, whilst the root exudates of non-host common bean had no effect on the zoospores. [Conclusion] P. sojae selects its host depending on the root exudates, which will provide a theoretical basis for further understanding the host selection mechanism of P. sojae.

Abstract:[Background] Staphylococcus aureus is a Gram-positive bacterium that can become a pathogen causing an array of diseases in animals and people. [Objective] To understand the multiple drug resistant situation of poultry Staphylococcus aureus in different areas of Anhui Province, and its characteristics of drug resistance and genotyping. [Methods] Sick poultry livers collected from different areas of Anhui Province as inoculation materials. In total, 103 multiple drug-resistant strains of Staphylococcus aureus were isolated. Then the resistant genotypes and molecular typing of Staphylococcus aureus were detected by PCR and ERIC-PCR respectively. [Results] The strains were resistant to 3 to 8 antibiotics. Most strains demonstrated multi-drug resistance to 5 antibiotics (43/103), followed by 4 antibiotics (21/103) and 6 antibiotics (22/103). The drug resistance rate of Staphylococcus aureu to β-lactam was the highest (79.6%), followed by aminoglycosides (71.8%). The detection rate of drug resistance gene from high to low were mecA (92.2%), aac(6′)/aph(2″) (76.7%), ermC (37.9%), ermA (13.6%) and femA (3.9%). Six different groups were obtained by ERIC-PCR molecular typing, and the dominant epidemic flora was the group Ⅱ (38/103). [Conclusion] Drug resistant genes of aminoglycosides, β-lactam and macrolides had high detection rates. There were genetic diversities among avian Staphylococcus aureus in areas of Anhui Province according to molecular typing. There was no significant correlation between ERIC-PCR molecular typing and drug resistance spectrum.

Abstract:[Background] Porcine epidemic diarrhea (PED) caused by porcine epidemic diarrhea virus (PEDV) is an acute intestinal infectious disease of pigs that is characterized by diarrhea, vomiting, and dehydration. Its massive outbreak has caused huge losses to the pig industry since 2010. Due to the poor understanding of the immune mechanism and invasion mechanism of PEDV, there is still no effective prevention and treatment about PED. [Objective] The main aim of this study is to explore the effects of ORF3 protein on the proliferation of PEDV in vitro. [Methods] Recombinant PEDV DR13 (attenuated) strains with orf3 genes from different origins or without orf3 gene were rescued by using reverse genetics operating system based on targeted RNA recombination. Then the Vero cells were infected with the acquired recombinant PEDV strains at a multiplicity of infection (MOI) of 0.1. The viral titers (TCID50) at 8, 16, 24, 32, 40, 48 hours post infection (hpi) were measured and the growth curve of each recombinant PEDV was drawn. The intact cells at 25 and 36 hpi were counted by using an automatic cell counting analyzer. Meanwhile, the cell viability were measured at 12, 24, 36, 48 hpi using Cell Counting Kit-8. [Results] Successful rescue of recombinant PEDV strains with or without orf3 was verified by using RT-PCR and observing the cytopathic effect (CPE). The results of immunohistochemistry assay indicated that orf3 gene of recombinant PEDV was expressed in Vero cells. The viral titers of recombinant PEDV strains with orf3 gene were significantly higher than that without orf3 gene. Furthermore, the statistical analysis results using SPSS showed that the numbers of intact cells left in the flasks infected with the recombinant PEDV strain with orf3 gene at both 25 and 36 hpi were significantly higher than that infected with the strain without orf3 gene and viability of the cells infected by recombinant PEDV strain with orf3 gene were significantly higher at 24, 36 and 48 hpi than that infected with the strain without orf3 gene. [Conclusion] PEDV ORF3 protein promotes the proliferation of PEDV on Vero cells, the mechanism of which might be the time delay of death of infected cells by the ORF3 protein. These results provided information on the function of PEDV orf3 gene and were helpful in understanding the replication mechanisms of PEDV.

Abstract:[Background] Calcimycin is a structural unique pyrrole polyether antibiotic produced by Streptomyces chartreusis NRRL3882, and exhibits multiple biological effects, but the regulatory mechanism of calcimycin biosynthesis remains unclear. [Objective] To study on the function of the potential regulatory gene calR2 encoding LuxR family homologous protein in calcimycin biosynthesis gene cluster. [Methods] The calR2 gene on calcimycin biosynthesis gene cluster was disrupted by PCR-targeting, and metabolites of the ΔcalR2 mutant and complementation strain were analyzed by HPLC. The calcimycin biosynthesis gene expression levels of ΔcalR2 mutant compared with the wild-type strain was analyzed by RT-qPCR. [Results] HPLC analysis of the fermentation products showed that the ΔcalR2 mutant could not produce calcimycin and the complementation strain restored the production of calcimycin. Gene expression analysis showed that the transcription levels of some essential genes in calcimycin biosynthesis obviously declined in ΔcalR2 mutant. [Conclusion] The putative LuxR family homologous protein CalR2 acts as a positive regulator involved in calcimycin biosynthesis.

Abstract:[Background] According to the clinical detection of wound infection is time-consuming and expensive, fast and convenient identification is imperative. [Objective] We investigated the stability of the liposomes by adding different components to the liposomal membranes, and their response to bacterial. [Methods] liposome encapsulated carboxyfluorescein were prepared with phosphocholine (PC) as a main lipid constituent, cholesterol, 10,12-tricosadiyonic acid (TCDA), 1,2-dipalmitoyl-sn-glycero-3-phospho-(1?-rac-glycerol) (DPPG), octadecylamine as stabilizing agents by thin-film and rehydration method. The bacterial suspensions and respective supernatants were incubated with fluorescent liposome to obtain the fluorescence increments according to the interaction between toxins and liposomes. [Results] DPPG and TCDA(10,12-Tricosadiyonic acid) increased the stability of the liposome, and octadecylamine decreased it. When incubated with bacterial suspensions and its supernatants of Staphylococcus aureus ATCC25923 and Pseudomonas aeruginosa PAO1, the obvious increase of the fluorescence intensity was observed, while incubated with Escherichia coli DH5α and PBS, the fluorescence intensity almost unchanged. [Conclusion] S. aureus and P. aeruginosa which release exotoxins can lyse liposomes but not by E. coli.

Abstract:[Background] As Salmonella resistance to fluoroquinolones has increased gradually, it is very urgent and important to study the mechanism of drug resistance. Proteomics analysis will provide new targets and directions for the study on resistance mechanism in Salmonella. [Objective] Proteomic analysis of Salmonella typhimurium was performed before and after induction, in order to lay the foundation for further studies on the mechanism in Salmonella resistance. [Methods] Ciprofloxacin was used to induce Salmonella typhimurium ATCC13311 to obtain resistance, screening and bioinformatics analysis of differential proteins were performed by using tandem mass tag (TMT). Besides, fifteen differential proteins were selected for (parallel reaction monitoring PRM) target verification. [Results] The results showed that a total of 318 differentially expressed proteins were screened, among which 159 proteins were up-regulated and 159 proteins were down-regulated. The KEGG pathways involved in these proteins mainly including bacterial chemotaxis, ABC transporters, two-component systems, etc; PRM was successfully quantitated to 13 validated proteins and the trend was consistent with TMT. [Conclusion] In this study, the proteomics analysis of Salmonella typhimurium parental strain and ciprofloxacin-resistant strain was conducted by TMT quantitatively combined with PRM target verification, screening out a variety of differential proteins and metabolic pathways, including efflux pump related proteins, outer membrane proteins, two-component related proteins and pathways, bacteria chemotaxis related proteins and pathways, etc. The study laid a certain foundation for further studies on the mechanism of fluoroquinolone resistance in Salmonella.

Abstract:L-aspartate alpha-decarboxylase could catalyze the decarboxylation of L-aspartic acid to generate beta-alanine, which is one of key enzymes in pantothenate metabolism, playing an important role in energy and lipid metabolism of all lives. It belongs to a small class of pyruvoyl-dependent enzymes, which has characteristic mechanisms of self-cleavage on pro-enzyme and substrate inactivation during catalysis. Here, we reviewed advances and achievements in molecular mechanism and modification of bacterial L-aspartate alpha-decarboxylase, and expected its application in biosynthesis of beta-alanine.

Abstract:EF-P (Elongation factor P) is a translation elongation factor commonly conserved in bacteria. Due to its L-shaped structure similar to tRNA, EF-P can rescue stalled ribosome caused by polyproline. Although it is not an essential protein in bacteria, it is crucial for bacterial fitness and virulence of some pathogens. In this paper, the structure, function and related research progress of bacterial EF-P are reviewed.

Abstract:Small RNAs are small, endogenous and non-coding RNAs and rich in eukaryotes, they regulate the gene expression through complete or non-complete complementary with the mRNA. In this review, we summarized the discovered classes of fungal small RNAs, protein factors biogenesis related with small RNAs, and provide a current analysis of the small RNAs mechanisms. This will provide the important reference for the scientists to further study the mechanisms of fungal small RNAs in growth and development.

Abstract:Light is an important and ubiquitous environmental signal that regulates bacterial metabolism and growth. On one hand photosynthetic bacteria swim to the zones with light intensity optimal for the functioning of the photon-driven carbon assimilation. On the other hand, some phototrophic bacteria also sense and capture light to derive energy for metabolisms other than photosynthesis. Beside the phototrophic bacteria, certain microbes use the light only for the purpose of communication and environmental positioning. Large variety of photosensory proteins is encoded in the bacterial genomes and responsible for these physiological functions. Here, we review the light-induced physiological and behavioral responses and the mechanism of light mediated signaling in bacteria, especially in nonphototrophic bacteria.

Abstract:Bioaugmentation, the process of adding designed microbial strains or mixed cultures to anaerobic digestion reaction system is a promising technique to increase biogas production yield, accelerate the start-up time of fermentation, enhance the utilization efficiency of raw material, shorten the recovery time of deteriorative system and improve the capacity of the reactor resistant to organic shock loading. Bioaugmentation focuses on taking advantage of functional microorganism for the specific physico-chemical properties of the bioprocess. In this review, research works about microbial breeding, influence factors of bioaugmentation and bioaugmentation mechanism, which carried out on the biogas production process have been summarized. In additional, some strategies that could be used or exploited to improve the success of this approach have also been discussed.

Abstract:To improve the quality of environmental microbiology course, flipped classroom was carried out in Nanjing University. The teaching content lay more stress on basic microbiology to provide necessary prerequisite to the scientific consideration of Environment Microbiology, whilst the arrangement of knowledge point underline the combination of microbiology with enviromental problems. The reform in course content could help to the differentiated instruction on applied technology and research talent. In the reform of teaching model, heuristic, interactive and investigated teaching methods were adopted in class. The flipped classroom was applied to increase the student’s participation in autonomous learning through interaction with students. The flipped classroom reform of Environment Microbiology lay emphasis on “learning” through feedback teaching to improving the comprehensive appreciation and application of Environment Microbiology.