Abstract:随着我国社会的发展, 人们对食品的质量有了越来越高地要求, 对食品对健康的影响也有了更深入的认识。与此同时, 国内科技工作者对食品微生物及其安全性研究给予了相当重视, 仅就2010年本刊发表的研究论文数量来看, 虽然“环境微生物”栏目有25篇(不包括环境微生物学专刊), 但“食品微生物”栏目论文数量也相当可观, 共发表了17篇论文。在相关工作中, 有关食品安全方面的论文有7篇, 其研究工作取得了一系列重要的进展, 如孙群等分析了冷藏鸡肉胴体中的细菌多样性, 筛选到了传统发酵豆瓣中产毒黄曲霉的高效拮抗菌; 陈双雅等研究了一种检测食源性变形杆菌簇致病菌的方法; 陈颖等采用MALDI-TOF质谱技术对克罗诺杆菌进了鉴定和分型; 赵广英等研制了辛辛那提弧菌选择性鉴别培养基; 陶妍等探索了茶多酚对金黄色葡萄球菌和铜绿假单胞菌的抑菌机理; 贾士儒等对嗜热链球菌CGMCC 1.1864所产的一种新型细菌素ST916进行了分析。这些研究工作属于我国食品微生物安全的研究重点方向之一。在酿酒微生物学以及微生物代谢等研究方面, 国内同行也给予了相应的重视，并取得了值得关注的进展。

Abstract:蛋白酶是食品工业中最重要的加工配料(辅料)之一, 蛋白酶在食品加工中的应用主要是利用了其对蛋白质所产生的多样化水解作用。许多受人欢迎的食品, 如干酪、啤酒和酱油等的生产过程都包含蛋白酶催化蛋白质水解这一关键性的反应。对这些食品加工技术的改进体现在基于对这些加工过程所涉及的各种化学变化的科学研究结果, 其中包括了用微生物发酵来产生不同的蛋白酶, 从而更有效地进行食品加工。因此, 对蛋白酶的性质及其发酵生产的相关研究倍受业内关注。

Abstract:In this study, we investigated a new current-producing strain, Shewanella marisflavi EP1 isolated from costal sediments of Xiamen, its decolorization capability and mechanism of several types of dyes such as azo, anthraquinone and triphenyl methane. The results indicated that these dyes could be decolorized efficiently and the maximum capacity was 925 mg/(g cell dry weight?d) of Malachite Green. Strain EP1 could utilize various kinds of carbon sources, such as glucose, sucrose, xylose, lactate, formate and citrate for the decolorization of Xylidine Ponceau 2R. EP1 was active for decolorization in wide ranges of pH (6?10), temperture (16 °C?40 °C), and NaCl concentations (0?8%). The optimal conditions were pH 8.0, 30 °C, 1%?2% NaCl and lactate as carbon source, with a highest decolorization rate of 99.95% within 10 h. UV-vis absorption spectra demonstrated that the mechanism of the azo dye was degradation in the range of 0?8% NaCl.

Abstract:A total of 56 endophytic bacteria were isolated from the stem, leaves and petioles of Davidia involucrate with tradational cultural methods. Of which, 17 endophytic bateria were selected to carry out succedent molecular studies. About 1 500 bp fragments of 16S rDNA were amplified by PCR method using the extracted genomic DNA as the templet. According to sequences analysis and comparison with the data of GenBank by BLAST, eleven endophytic bacreia were classed to Bacillus genera, the identities are from 95% to 98%, two were classed to Lysinibacillus genera, the identities are 97% and 99%, one were classed to Bordetella genus, the identity was 95%, and one was similar to a reported uncultured bacterium, the identity was 96%. Bacillus was the dominant genus among the endophytic bacteria in Davidia involucrate. The phylogenic tree showed that the 15 endophytic bacteria clustered two main branches.

Abstract:Arbuscular mycorrhizal (AM) fungus (Glomus intraradices) was inoculated to the host plant (Allium fistulosum) and grown in three-part pot culture system, with addition of 4 mmol/L different forms of exogenous nitrogen, 1% glucose and root exudates into the mycelium compartment, effects of glucose and root exudates on the assimilation of different forms of nitrogen and production of arginine by arbuscular mycorrhizal fungus were examined by measuring arginine contents of the extraradical mycelium (ERM) and mycorrhizal roots. The results showed that the absorption capacity of ERM to different forms of exogenous nitrogen and produce arginine is ranked in order of Urea>Gln>NH₄NO₃>Arg/Gly>NH₄Cl>KNO₃; The capability of arginine formation in mycorrhizal roots was ranked in order of Arg>Gln>Urea>NH₄NO₃>Gly>NH₄Cl>KNO₃. Glucose and root exudates increased the dry weight of ERM and spore amount, but reduced arginine concentration in ERM and mycorrhizal roots. These re-sults indicated that the capacity of assimilation of different forms of exogenous nitrogen by AM fungus were different, glucose and root exudates reduced the capacity of assimilation of exogenous nitrogen and production of arginine by AM fungus.

Abstract:The alkane-degrading bacterium and methanogenic were the important functional populations in oil reservoirs and their diversities were investigated by FISH and DGGE, respectively. The DGGE profiles showed great difference between the alkB genes in samples. And the major bands detected in injection wells were obviously more than them in production wells. The FISH results indicated that the quantity of archaea was much more than bacteria in the samples and they had close spatial distribution in situ. The results indicated that alkane-degrading bacterium and methanogenic populations were diverse in oil reservoirs and formed compact aggregates in situ. The incubation of Shengli oilfield production water degraded more than 50% residual oil during 130 d culture, with the production rate of methane reaching up to 1.57×10^?2 mmol/(L?d). Molecular analysis of the functional populations of microbial community in oilfield will provide the information for better application of microbial enhanced oil recovery.

Abstract:The fungal strain CL-3 was isolated from the root of wild Cymbidium goeringii with using conventional isolation method. The inoculum of strain CL-3 was used to study its interaction with its host plant. According to the morphological features examination and rDNA ITS sequence analysis, the closest relative of the strain was Acremonium strictum, with the similarity of 100%. After two months of symbioses culture, the fresh biomass of C. goeringii inoculated with CL-3 increased by 80.5%, and the endophytic CL-3 was re-isolated from the seedlings. The statistics showed that the difference between inoculation group and control group was significant. The presence of the fungus in the tissues was stud-ied with paraffin-cut section. The results showed that the fungus was observed in inner tissues of roots, indicating that the symbiosis relationship between Cymbidium goeringii and fungi could be established.

Abstract:Biolog is defined as the emitted electrons while the microorganisms utilize carbon source combine with tetrazolium salt dyestuff, then take place color-reduction reaction which show the difference of carbon source utilization. The utilizations were analyzed with principal component analysis (PCA). The main carbon source utilized by microbial on the jujube surface included carboxylic acids, amino acids, phenolic compounds, amine and tween. The utilization of carbon source showed the markedly increase with extend of the time the jujube stored . The utilization of carbon source from the microbial on the surface of the jujubes stored for 30 days was higher than that of 15 days. The utilization of carbon source of the microorganisms on the jujube surface after treating with fresh agents was low. Principal component analysis for 31 carbon source on the ECO microplate showed. Characteristic value contribution of PC 1 was 78.54% and characteristic value contribution of PC 2 was 19.06%.

Abstract:Bacterial adhesion to hydrocarbons (BATH) and hydrophobic interaction chromatography (HIC) were employed to determine cell surface hydrophobicity (CSH) of Ralstonia solanacearum, respectively. The effects of the ratio of bacterial suspension to n-dodecane in the BATH assays and the injection volume of bacterial suspension in the HIC assays on the measurement of CSH were investigated. The optimal conditions for CSH analysis were as follow: the ratio of bacterial suspension (OD₆₀₀=0.5) to n-dodecane was 2:1 and the injection volume of bacterial suspension (OD₆₀₀=1.0) was 0.2 mL. Under these conditions, a good linear relationships between BATH and HIC methods was obtained (r=0.99). Moreover, HIC method was applied to detect the variation of CSH during growth of Ralstonia solanacearum. The results indicated that the CSH decreased with culture time and approached a plateau after 24 h of incubation, and a negative correlation between CSH and EPSⅠ (extracellular polysaccharide) content of cell surface was observed. The experimental results of three Ralstonia so-lanacearum stains of different virulence further confirmed that the CSH decreased with increasing EPSⅠcontent.

Abstract:To obtain high efficiency of MLF starter cultures, the effects of alcohol stress treatments on the growth, intracellular malolactic enzyme (MLE) activity, freeze-drying viability, and membrane fatty acid composition of Oenococcus oeni SD-2a strain were studied. The results showed that alcohol stress treatments did strongly decrease bacterial growth rate and cell biomass, but increased distinctly MLE activity. Compared with control treatment, 5% alcohol stress treatment decreased bacterial freeze-drying viability, and 10% alcohol stress treatment increased bacterial freeze-drying viability. Concerning the membrane fatty acid composition, it was observed that the unsaturated : saturated fatty acid ratio in the former treatment is 1.12, which is lower than that of control by 26.3%, and the unsatu-rated : saturated fatty acid ratio in the latter treatment is 2.28, which is higher than that of control by 50.6%. So it was assumed that O. oeni SD-2a adopted different adaptive mechanisms in the membrane levels under different alcohol stress conditions, and its membrane fatty acid composition might have a close relationship with bacterial freeze-drying viability.

Abstract:Three filamentous fungal strains were isolated form Carassius auratus eggs with Saprolegniasis, and strain JL1 was proved to be pathogenic to Carassius auratus eggs by artificial infection. Therefore, morphology and growth characteristics of strain JL1 were studied, and the phylogenetic analysis based on its ITS rDNA sequence was further conducted. The experimental results showed that the hyphae of strain JL1 was aseptate, transparent and seldom branched. Its zoosporangia were often clavate and renewed internally. Primary zoospore was multi-row arrangement in zoosporangia and discharged in Saprolegnia fashion. Spherical oogonia was attached by monoclinous or diclinous antheridium hyphae. The ITS rDNA sequences of strain JL1 was naturally clustered with ITS rDNA sequences of Saprolegnia sp. submitted to GenBank with 99% of homology, and had closest relationship with Saprolegnia sp. H (accession number: EF460351). Combined morphological characterization with phylogenetic analysis based on ITS rDNA sequence, strain JL1 was identified as Saprolegnia sp.. In addition, strain JL1 could grow at 5 °C?30 °C and pH 4?11, its optimum growing temperature and pH were 25 °C?30 °C and 6?9, respectively. Strain JL1 was sensitive to sodium chloride, its growth could be completely inhibited by 2% NaCl, which could serve as a foundation for the Saprolegniasis control.

Abstract:The objective of this study was to analyze the correlation between genetic variation and pathogenicity of field sample virus during the propagation in sensitive cells. 36-day-old pigs were challenged with PRRSV GSLZ-1/2009 cell propagated virus and field sample virus after genetic variation analyse. Carry out real-time monitor and dynamics analyse to clinical symptoms, signs of change and the levels of antibody and inflammatory factors, and the histopathologic changes were observed under light microscope. The results showed that the disease-related genes was no variation, the antibody, inflammatory factors response and histopathologic lesions induced by field sample virus were more powerful than those induced by cell propagated virus. The researches indicated that virulence of field PRRSV could be weakened when it propagated in cells, and there are other possible factors except genetic variation playing on the role of virulence weaken.

Abstract:A total of 62 endophytic fungi were isolated from the plant tissues (root, stem, leaf and flower) of medicinal plants Fagopyrum dibotrys and Fagopyrum tataricum. The antimicrobial activity from isolated endophytic fungi were detected using agar diffusion method with Staphylococcus aureus, Es-cherichia coli, Bacillus subtilis [CMCC (B) 63501], Fusarium graminearum, Fusarium oxysporum f. sp. cucumerinum and Pythium aphanidermatum as indicator microorganisms. The results showed that the ethanol extracts of three isolated entophytic fungi strain KQH-01, KQH-02 and JQY-1 had relatively strong antibiotic activity to some indicator microorganisms. By using morphological and molecular identification, strain KQH-01was determined to belong to the genus Xylaria sp., and strains KQH-02 and JQY-1 were identified as Chaetomium globosum and Botryosphaeria dothidea respectively.

Abstract:A bacterial strain producing conjugated linoleic acid was isolated from the goat rumen in Erdos, Inner Mongolia, the strain was designated as RB111. CLA production by the strain reached 269.2 mg/L, in which the percentage content of cis9, trans11-CLA accounted for 52.64% and that of trans10, cis12-CLA accounted for 47.36%. The strain RB111 was identified using its morphological characteristics, fatty acid composition and physiological and biochemical properties, as well as its 16S rRNA gene sequence. The strain RB111 shares 99% sequence identity with the type strain NCDO 599^T of Streptococcus infantarius. The result of fatty acid composition analysis revealed that the major fatty acids present in the strain RB111 were C16:0, C18:1 ω9c and C18:0, the total account of the three kinds of fatty acids was 60.64%. The morphological characteristics and the results of physiological and biochemical properties of the strain were in well agreement with that of the type strain NCDO 599^T of Streptococcus infantarius. On the basis of these data, the strain RB111 was definited to Streptococcus infantarius.

Abstract:The biological function of a formerly constructed nonencapsuled mutant Δcps2B from 05ZYH33 was characterized, and its protection against infection was evaluated. We found that Δcps2B have reduced ability to form long chain capsule polysaccharide and no longer agglutinated with the specific anti-capsular serum. The Δcps2B could be cleared more easily by the whole blood of human and piglet, while the capacity of adhesion to epithelial cells increased greatly. Animal infection experiment demonstrated that the Δcps2B protect mice from lethal challenge with S. suis 2. These observations indicate that the capsule plays an essential role in the pathogenesis and invasiveness of S. suis 2.

Abstract:A new therapeutic approach for Staphylococcus epidermidis biofilm-associated infections was provided by the study of active ingredient of Chinese medicine matrine on S. epidermidis biofilm inhibition. XTT reduction assay was used to evaluate matrine on the initial adhesion of S. epidermidis and biofilm metabolism, and microscope was applied to observe biofilm morphology. The results showed that SMIC₅₀ and SMIC₈₀ of matrine against S. epidermidis biofilms were 62.5 mg/L and 500 mg/L respectively, 1 000 mg/L of matrine inhibited the early adherence of S. epidermidis, and 250 mg/L of matrine had a significantly inhibitory effect on S. epidermidis biofilm morphology. The study demonstrated that matrine could inhibit S. epidermidis biofilm formation and adhesion.

Abstract:To explore fluconazole’s effect mechanism, we investigated the changes of viability rate, reactive oxygen species (ROS), mitochondrial membrane potential (△Ψm) and cell cycle of Candida tropicalis after treatment with fluconazole. The minimum inhibitory concentration (MIC) of the clinical isolates Candida tropicalis to fluconazole were tested by NCCLS M27-A microdilution method. After treatment wth different concentration of fluconazole, viability rate, the intracellular accumulation of ROS, the loss of mitochondrial membrane potential △Ψm and cell cycle of Candida tropicalis were detected with flow cytometry, respectively After treatment with fluconazole, there were no significant variation among viability rate, ROS, mitochondrial membrane potential △Ψm and cell cycle in flu-conazole-resistant strains, but a decrease of mitochondrial membrane potential △Ψm and viability rate, an increase of ROS accumulation were detected in a time-dose-dependent manner in flucona-zole-susceptibile strains. A majority of Candida tropicalis were arrested in G2/M phase and apoptosis peak was seen. Free radicals scavenger glutathione inhibited ROS production, prevented G2/M arrest and decreased apoptosis in fluconazole-susceptibile strains. According to it, fluconazole maybe induce intracellular accumulation of ROS and decrease of mitochondrial membrane potential △Ψm, which could result in apoptosis of Candida tropicalis.

Abstract:CLA (Conjugated linoleic acid, CLA) possesses a wide range of biological activities including anti-cancer activity, anti-atherosclerosis activity, capability of helping reduce weight fat and regulate immune system. The fatty acid isomerase from bacteria, which catalyzes the isomerization of linoleic acid (LA) to CLA production, is a promising candidate for other approachs. This paper introduces the source of linoleate isomerase, the mechanism of its function as well as reviewing recent advances re-garding the key property of this important enzyme. The preparation of linoleate isomerase and how to use it to produce high yield of isomers of conjugated linoleic acid with high purity are also demonstrated, which will help to realize sustainability and industrial scale production of conjugated linoleic acid.

Abstract:The taxonomy position and life cycles of culture-difficult fungi which associated with plants at various symbiosis extent are very completed and diverse. Most of these fungi can finish their life cycles when the other living things (such as plant, bacteria etc.) present. The non-obligate with no-vivo nutrition culture-difficult fungi are easier to be pure cultured than that of obligate with vivo nutrition one. On the basis of introducing taxonomy position, life cycle and symbiosis type of culture-difficult fungi associated with plants, the present author summarized the cultural characteristics and method for these fungi, as well as discussing the research trend and prospects, in order to provide new idea and basis for further investigating the pure culture of the fungi.

Abstract:Microbiology, as the major course of biological engineering, requires the better practical ability for the students. However, there is obvious problem on a few of comprehensive designing experiment and many proving experiments in the teaching. In order to train the students’ operating ability of basic skills in the microbiology experiments and discovering and solving problems at a higher level, the courses of experiments of microbiology have been adjusted since 2006. The opening comprehensive experiment of “Isolation, Cultivation and Identification of Environmental Microbe” has been added in the courses of the microbiology experiment. The students were asked to search correlative documents and design the experimental protocol independently, and then carried out the experiment with the guide of the instructor. Meanwhile, the comprehensive experiment was incorporated with the innovation match of Yanshan University, which increases the students’ interest and enthusiasm for the experiment. The operational skills of the students have been enhanced significantly. In addition, the abilities of in-dependent solving problems and cooperation in the team have been increased. The excellent teaching result has been achieved with five years’ practice.

Abstract:Experiment teaching is very important for postgraduate education. This paper described the ex-perimental design and characteristic of the microbiology experiment course for postgraduates of China Agricultural University, Modern Techniques of Microbiology. Some experiences about construction of teaching team, setting of the experiments, implementation of the course and compiling textbook are introduced.

Abstract:Fermentation engineering is a very important specialized course for undergraduates majoring in biological engineering specialty, and its teaching quality will affect students’ professional quality, in recent years, the course reform has been conducted. For the arrangements of teaching content system, the concept of “One center, Two combination, Three levels” was put forward. About the teaching strate-gies, the comprehensive application of four strategies which involved “Predicting, Questioning, Clari-fying and Summarizing” was explored. In the way of teaching medium, a variety of methods and tech-niques were attempted. In the process of practical teaching, new experimental weeks and the form of experimental groups were adopted, and the teaching evaluation system was perfected, meanwhile, at-taching importance to students’ innovative ability and professional skill to improve teaching quality.

Abstract:One-step multiplex reverse transcription polymerase chain reaction (M-RT-PCR) was established and optimized for the simultaneous detection of potato virus X, potato virus Y, potato virus A and potato leafroll virus. The primers for PVX (732 bp), PVY (422 bp), PVA (132 bp) and PLRV (336 bp) fragments were designed based on viral coat protein gene. The sensitivity of detection was about 7.8 pg/μL RNA. No fragments were obtained from PVM, PVS, AMV, TMV and PSTVd. The results showed that it was a specific, sensitive detecting method and quicker, simpler, more efficient and cheaper than two-step multiple RT-PCR. It was provided an effective method of the detection for potato virus.