基于海带水解液的细菌Clostridium sp.WANY51发酵产氢性能

【目的】探究菌株Clostridium sp. WANY51利用海带水解液作为底物发酵产氢的能力,为研究大型海藻的厌氧发酵产氢机制奠定基础。【方法】以海带水解液为唯一培养基,通过三层平板法从潮间带污泥中分离出一株厌氧发酵产氢细菌。通过显微镜观察和16S rRNA基因序列分析,该菌株命名为Clostridium sp. WANY51。通过设置海带水解液中的固液质量体积比（下称“固液比”）和起始pH,分析菌株产氢性能。【结果】菌株WANY51利用海带水解液发酵产氢的代谢产物主要是丁酸,属于丁酸代谢途径。菌株WANY51在起始pH值5.0～9.0范围内都能够发酵产氢,初始pH值为7时产氢量最高,达到（19.74±0.26）mL/g。海带水解液固液比对菌株发酵产氢量具有较显著影响,当固液比为4%时产氢量最高,达到（24.76±0.31）mL/g。【结论】菌株Clostridium sp. WANY51利用海带水解液为底物时,起始pH为7和固液比为4%时产氢效果最佳。     

中国对虾素在大肠杆菌(Escherichia coli)中的重组表达

中国对虾素是从中国对虾血细胞中克隆得到的一种抗菌肽。为了进一步研究中国对虾素(CHP)的功能并为制备特异性抗体作准备，采用大肠杆菌表达外源蛋白的方法，进行了对虾素原核表达的研究。根据从中国对虾血细胞中克隆得到的对虾素基因设计特异性引物扩增中国对虾素成熟肽基因(CHP)，插入原核表达载体pGEX-4T-1中，在E．coli BL21表达融合蛋白GST-CHP．结果表明，不同表达菌株的融合蛋白表达量为30％—34％，同一菌株在诱导5h后能达到最高表达量。利用GST亲和层析纯化融合蛋白，将融合蛋白用凝血酶裂解以得到CHP，其分子量约为5．6kDa，N-端测序结果与期望的成熟对虾肽序列一致。用液体生长抑制方法检测活性，表明重组GST-CHP蛋白及CHP均表现出对大肠杆菌的抑菌活性。     

一株兼性厌氧硝酸盐/Fe(Ⅲ)还原菌的分离及鉴定

表生环境中广泛存在以硝酸盐或Fe(Ⅲ)为电子受体、有机物或还原性无机盐为电子供体进行生长的微生物。硝酸盐还原菌具有降低水体硝态氮浓度的功能(Gesche等,2010),而铁还原菌具有固碳、磷(代谢产物Fe(Ⅱ)与CO32-、PO43-等反     

芽孢杆菌Cr23还原Cr6+的初步研究

硫酸盐还原菌(Sulfate reduction bacteria)是一类在土壤或水体重金属污染生物修复中能够发挥重要作用的微生物类群。本实验采用摇瓶培养和还原率的测定方法,研究了一株采自海岸潮间带土壤的SRB芽孢杆菌还原Cr6+的效率及培养条件对其还原Cr6+效率的影响。结果显示该菌株可在Cr6+浓度600 mg/L条件下正常生长,300 mg/L浓度下的生长最佳,Cr6+还原率高达75%。培养液中的碳源、氮源和pH对该菌株的Cr6+还原率有显著影响,其中以乙酸钠或柠檬酸钠为碳源,硝酸钠为氮源的还原效率最高;初步结果显示,菌株Cr23是一株环境适应性和Cr6+还原能力较强的SRB,具可应用于土壤或水体铬污染修复的潜力。     

Characterization of halophilic C50 carotenoid-producing archaea isolated from solar saltworks in Bohai Bay,China

Halophilic archaea comprise the majority of microorganisms found in hypersaline environments. C50 carotenoids accumulated in archaea cells are considered potential biotechnological products and possess a number of biological functions. Ten red colordes were isolated from brine water in a saltem crystaltizer pond of the Hangu Saltworks, China. 16S rRNA gene sequence analysis showed that the colonies belonged to the extremely halophilic archaea genera Halobacterium and Halorubrum. Two representative strains, Halobacterium strain SP-2 and Halorubrum strain SP-4, were selected for further study on the phenotypic characteristics and effects of salinity and pH on accumulation and composition of pigments in their cells. The archaeal strains were isolated and grown in a culture medium prepared by dissolving yeast extract （10 g/L） and acid-hydrolyzed casein （7.5 g/L） into brine water obtained from a I.ocal salt pond. Their optimum salinity and pH for growth were 250 and 7, respectively, although pigment accumulation （OD490/ mL broth） was highest at pH 8. In addition, at 150-300 salinity, increasing salinity resulted in decreasing pigment accumulation. Analysis of the UV-Vis spectrum, TLC and HLPC chromatograms showed that C50 carotenoid bacterioruberin is the major pigment in both strains.     

高效硝化与反硝化功能菌株的分离筛选及其性能研究

本研究利用选择培养基从鳗鲡精养殖池和循环水水处理系统中分离筛选出二株脱氮细菌,应用16S rRNA分子生物学鉴定,确定菌株的种属。菌株NB-1属于芽孢杆菌属（Bacillus）、菌株DB-1是恶臭假单胞菌（Pseudomonas putida）。对菌株硝化及反硝化作用性能的研究结果表明：菌株NB-1具有良好的亚硝化及硝化作用性能,在投菌量为0.025%时,氨氮降解率为69.5%,亚硝酸盐氮降解率为99.2%。菌株DB-1在厌氧条件下表现出良好的反硝化作用性能,最适投菌量为0.6%,最佳C/N为12,对硝酸盐氮的降解率为94.6%,对总氮的降解率为64.0%。因此本研究筛选出的二株脱氮细菌可以广泛应用于养殖水体水质调控,具有良好的市场应用前景。     

Intraspecific diversity of Aureobasidium pullulans strains from different marine environments

Totally more than 500 yeast strains were isolated from seawater, sea sediments, mud of sea salterns, marine fish guts and marine algae. The results of routine and molecular biology identification methods show that nine strains among these marine yeasts belong to Aureobasidium pullulans, although the morphologies of their colonies are very different. The marine yeasts isolated from different marine environments indicate that A. pullulans is widely distributed in different environmental conditions. These Aureobasidium pullulans strains include A. pullulans 4#2, A. pullulans N13d, A. pullulans HN3-11, A. pullulans HN2-3, A. pullulans JHSc, A. pullulans HN4.7, A. pullulans HN5.3, A. pullulans HN6.2 and A. pullulans W13a. A. pullulans 4#2 could produce cellulase and single cell protein. A. pullulans N13d could produce protease, lipase, amylase and cellulase. Both A. pullulans HN3-11 and A. pullulans HN2-3 were able to produce protease, lipase and cellulase. A. pullulans JHSc could secrete cellulase and killer toxin. Both A. pullulans HN4.7 and A. pullulans HN5.3 could yield lipase and cellulase. A. pullulans W13a was able to secrete extracellular amylase and cellulase while A. pullulans HN4.7 and A. pullulans N13d could produce siderophores. This means that different A. pullulans strains from different marine environments have different physiological characteristics, which may be applied in many different biotechnological industries.     

抑制黄曲霉毒素的深海环状芽胞杆菌发酵条件优化

环状芽胞杆菌(Bacillus circulans)菌株FA13在M2培养基中的发酵无细胞上清液对寄生曲霉(Aspergillus parasiticus)突变菌株NFRI-95菌丝生长和黄曲霉毒素的产生表现出明显的抑制作用。为了最大限度地提高活性物质的产量,本研究对从南大西洋深海沉积物中分离到的环状芽胞杆菌菌株FA13的发酵条件进行了均匀设计发酵优化。优化后,菌株FA13的发酵液10倍稀释液对寄生曲霉突变菌株NFRI-95的菌丝生长抑制率从10.98%提高到70.57%,黄曲霉毒素产生抑制率从41.43%提高到100.00%;对应的发酵条件为发酵温度38.70℃,接种量6.00%,海水体积占比0.00%,培养基pH 8.71,培养时间6 d。