乳酸菌产细菌素研究进展

乳酸菌产生的细菌素是一类具有活性的多肽或蛋白质物质,大部分细菌素对近缘关系的细菌有抑制作用,少数细菌素抑菌谱很广.细菌素可分为热稳定的小分子肽,热敏感的大分子蛋白和羊毛硫抗生素.本文综述了细菌素的特性、生物合成和应用.     

菌肥肥效测定

采用ｔ检验对某菌进行肥效测定,结果表明,该菌肥对小麦苗生长有明显的促进作用。     

光合细菌与嗜热脂肪芽孢杆菌融合子的制备与鉴定

本文采用嗜热脂肪芽孢杆菌与试验室保存的耐盐荚膜红假单胞菌为出发菌株,采用原生质体融合技术选育耐高温光合细菌。比较了耐盐荚膜红假单胞菌、嗜热脂肪芽孢杆菌和融合子在营养需求、细菌的耐盐性、抑菌实验、融合子降解氨氮和亚硝基氮功能的测定等方面的异同,以对其进行鉴定。     

细菌Bacillus sp. NS-3和灰葡萄孢对松材线虫的诱引

通过＂水琼脂平板移行法＂和＂玻管法＂,研究了松材线虫拮抗细菌Bacillus sp.NS-3和真菌灰葡萄孢引诱线虫的能力.结果表明：初始随着作用时间的延长,细菌引诱线虫能力增加,NS-3在72小时（3天）达到对线虫的最大吸引,而随着作用时间的继续延长,细菌吸引线虫能力下降,最后细菌NS-3对线虫的吸引力为负值,从而说明线虫对致病细菌NS-3有趋避行为;真菌灰葡萄孢对松材线虫的诱引能力比较稳定,线虫对真菌没有趋避行为.进一步研究发现,枯木浸出液诱引线虫能力最大,其次是菌株NS-3的发酵液,然后是灰葡萄孢真菌的发酵液.而且,枯木浸出液和灰葡萄孢真菌的发酵液煮沸后诱引线虫能力均有所下降,但差值不大,说明枯木和真菌中对松材线虫起诱引作用的物质并没有因高温而完全失去;而细菌菌株NS-3的发酵液的发酵液煮沸后诱引线虫能力急剧下降,从而推测细菌中诱引线虫因子为挥发性的物质.     

低温几丁质酶生产菌的筛选鉴定与产酶条件研究

以胶体几丁质为唯一碳源,从大连渤海湾的底泥样品中分离到1株高产低温几丁质酶的海洋细菌,命名为DL-06。采用单因素优化方法确定该菌株产低温几丁质酶的最佳条件,结果表明:胶体几丁质5.0 g/L,胰蛋白胨5.0 g/L,发酵温度20℃,pH 7.0,2%接种量,装液量60%,转速130 r/min,陈海水1.0 L,发酵时间30 h,在该条件下酶活力达6.87 U/mL。     

乳酸菌的生理功能及在饲料发酵中的应用

乳酸菌具有促进营养物质的消化和吸收、降低血清胆固醇、调节肠道菌群平衡、激活机体免疫系统、改善食品风味和预防癌症等多方面的生理功能。利用益生乳酸菌发酵而成的饲料对促进动物的健康生长具有重要的实践意义,这种功能性发酵饲料近年在我国畜牧业中发展十分迅速,有着广阔的生产和应用前景。本文就近几年来关于乳酸菌的生理功能、益生菌发酵饲料的种类及乳酸菌发酵饲料在动物生产中的应用进行综述,并对其发展前景进行展望。     

Key gene networks that control magnetosome biomineralization in magnetotactic bacteria

Magnetotactic bacteria (MTB) are a group of phylogenetically and morphologically diverse prokaryotes that have the capability of sensing Earth''s magnetic field via nanocrystals of magnetic iron minerals. These crystals are enclosed within intracellular membranes or organelles known as magnetosomes and enable a sensing function known as magnetotaxis. Although MTB were discovered over half a century ago, the study of the magnetosome biogenesis and organization remains limited to a few cultured MTB strains. Here, we present an integrative genomic and phenomic analysis to investigate the genetic basis of magnetosome biomineralization in both cultured and uncultured strains from phylogenetically diverse MTB groups. The magnetosome gene contents/networks of strains are correlated with magnetic particle morphology and chain configuration. We propose a general model for gene networks that control/regulate magnetosome biogenesis and chain assembly in MTB systems.     

枇杷叶围微生物分离及灰斑病菌拮抗菌筛选

从健康"解放钟"枇杷叶上分离采集微生物,以筛选枇杷灰斑病拮抗菌。结果表明:在枇杷的叶围微生物中,细菌占74%以上,属优势菌群,其次是真菌,放线菌比例最少;微生物总量的季节变化趋势是春季>夏季>秋季。其中XI-6和XI-8两菌株对灰斑病病原菌菌丝生长及孢子萌发均有较强抑制作用,经鉴定两菌株为芽孢杆菌属(Bacillus)。     

Leptotrichia hongkongensis sp. nov., a novel Leptotrichia species with the oral cavity as its natural reservoir

A straight, non-sporulating, Gram-variable bacillus (HKU24T) was recovered from the blood culture of a patient with metastatic breast carcinoma. After repeated subculturing in BACTEC Plus Anaerobic/F blood culture broth, HKU24T grew on brucella agar as non-hemolytic, pinpoint colonies after 96 h of incubation at 37 °C in an anaerobic environment and aerobic environment with 5% CO2. Growth was enhanced with a streak of Staphylococcus aureus. HKU24T was non-motile and catalase-negative, but positive for alkaline phosphatase, β-glucosidase, and α-glucosidase. It hydrolyzed phenylphosphonate and reduced resazurin. 16S rRNA, groEL, gyrB, recA, and rpoB sequencing showed that HKU24T occupies a distinct phylogenetic position among the Leptotrichia species, being most closely related to Leptotrichia trevisanii. Using HKU24T groEL, gyrB, recA, and rpoB gene-specific primers, fragments of these genes were amplified from one of 20 oral specimens. Based on phenotypic and genotypic characteristics, we propose a new species, Leptotrichia hongkongensis sp. nov., to describe this bacterium.     

间歇性热处理对齐整小核菌核生活力的影响

该文作者通过对用不同营养基质培养出的齐整小核菌菌核作间歇性热处理，其试验结果表明：菌核致死温度为55℃10分钟；但五种培养基中培养出的菌核在热处理中萌发无显著差异。