发酵生产细菌纤维素的研究进展

该文主要介绍了细菌纤维素发酵生产的研究。即细菌纤维素产生菌株的选育和发酵工艺的研究进展。     

细菌纤维素高产菌株的诱变选育和发酵条件研究

为了选育高产细菌纤维素的木葡糖酸醋杆菌((Gluconacetobacter oboediens)突变菌株,通过硫酸二乙酯和氯化锂复合诱变,得到-株产细菌纤维素能力最高的突变菌株GO2,其细菌纤维素产量为9.91 g/L,比出发菌株提高36.5%.同时确定突变菌株GO2的静置培养条件为发酵时间为6 d,接种量为80(v/v),面积/体积比为1.58～2.08 cm-1.     

等离子体注入诱变选育细菌纤维素高产菌株

为了选育高产细菌纤维素的木葡糖酸醋杆菌(Gluconacetobacter xylinum)突变株,通过等离子体注入诱变,筛选得到一株产细菌纤维素能力最高的突变株GX-5,其细菌纤维素产量为4.162 g/L,比出发菌株提高了83.19%。     

细菌纤维素的研究进展

细菌纤维素是一种新型生物合成原料,它有许多优于植物纤维的特点。目前已经发现有九个菌属可以产生细菌纤维素,其中以醋酸杆菌属的木醋杆菌产纤维素能力最强。提高细菌纤维素产量已经成为目前世界研究的热点问题,主要通过发酵工艺的优化、高产菌株的选育以及基因工程等一些手段来实现。     

细菌纤维素发酵生产及其改性研究进展

细菌纤维素有很好的持水性、稳定性和很高的抗拉强度、生物适应性,在医学和食品领域有广阔的应用前景.本论文阐述了细菌纤维素生产的主要菌株及其特性,生产纤维素的微生物营养代谢、发酵方式和基本条件,并概述了细菌纤维素的基本改性方法,这对深入研究和开发利用细菌纤维素有一定的指导意义.     

一株产细菌纤维素菌株的分离和初步鉴定

细菌纤维素具有纤维素化学纯度高和拥有超微纤维网结构这种独特性,目前已成功应用到造纸、纺织品和食品工业中,作为生物材料还可用于化妆品、医药等行业。本实验从红茶茵液中分离、筛选出一株纤维素生产细菌Axy—I,通过观察其显微形态和培养特征,同时结合分子鉴定,初步鉴别出该菌株为Axy—I菌株为葡糖酸醋酸杆菌（Gluconacetobactersp．）。同时分析比较该菌株在不同培养基和培养条件下的产物得率、细菌纤维素形态和扫描电镜微结构。     

不同培养方式生产细菌纤维素的研究

采用RBD反应器与传统静态培养方式生产细菌纤维素,对2种培养方式的发酵动力学参数进行了分析和讨论。结果表明,实验菌株QAX993适合在RBD反应器中生产细菌纤维素,产量比静态培养方式提高了2.79g/L。     

微生物生产的纤维素--细菌纤维素

介绍了一种新型的纤维素———细菌纤维素。对细菌纤维素的结构、性质、生产和应用进行了介绍,指 出细菌纤维素是一种有广阔前景的产品。     

木醋杆菌M096生产细菌纤维素的发酵条件

探讨温度、初始pH值、碳源和氮源对细菌纤维素产量的影响,以确定生产菌株发酵生产细菌纤维素的条件.结果显示,木醋杆菌M096发酵生产细菌纤维素的培养条件是:发酵温度25℃,初始pH值最适范围是5.8～6.6,最佳碳源为蔗糖且最适浓度是8%,最佳氮源为牛肉膏且最适浓度是1.5%.     

利用谷氨酸提取液生产细菌纤维素的研究

探讨了利用谷氨酸提取液生产细菌纤维素的方法，研究了接种量、糖化液的添加量、温度、pH值、发酵培养基的厚度、发酵时间等对生产细菌纤维素的影响，确定了谷氨酸提取液生产细菌纤维素的最适工艺条件为：糖化液20％，接种量3％-4％，温度28—32℃，发酵起始pH3．6—3．8，静置发酵时。发酵培养基深度1．2～2．0cm，发酵时间6～7d。     

细菌纤维素生产及应用研究进展

细菌纤维素是经微生物发酵形成的新型生物合成材料,由于其性质特殊而受到国内外广大学者的关注.该文重点介绍了近几年国内外为提高细菌纤维素产量而进行的高产菌菌种选育、培养基优化、发酵条件和发酵模式等方面的研究;同时对重要应用进行了阐述.     

Characterization of Bacterial Cellulose by Gluconacetobacter hansenii CGMCC 3917

In this study, comprehensive characterization and drying methods on properties of bacterial cellulose were analyzed. Bacterial cellulose was prepared by Gluconacetobacter hansenii CGMCC 3917, which was mutated by high hydrostatic pressure (HHP) treatment. Bacterial cellulose is mainly comprised of cellulose Iα with high crystallinity and purity. High‐water holding and absorption capacity were examined by reticulated structure. Thermogravimetric analysis showed high thermal stability. High tensile strength and Young's modulus indicated its mechanical properties. The rheological analysis showed that bacterial cellulose had good consistency and viscosity. These results indicated that bacterial cellulose is a potential food additive and also could be used for a food packaging material. The high textural stability during freeze–thaw cycles makes bacterial cellulose an effective additive for frozen food products. In addition, the properties of bacterial cellulose can be affected by drying methods. Our results suggest that the bacterial cellulose produced from HHP‐mutant strain has an effective characterization, which can be used for a wide range of applications in food industry.     

醋杆菌产纤维素发酵培养基的优化

本文在已筛选出在摇瓶培养条件下高产细菌纤维素菌株--醋杆菌C2的基础上,研究了不同碳氮源及无机盐对该菌株产纤维素的影响,并优化了该菌株产纤维素的最佳培养基。醋杆菌C2的最适碳源为蔗糖,D-甘露糖醇,最适氮源为蛋白胨,酵母粉,无机盐为MgSO4•7H2O和柠檬酸三钠;经正交试验确定该菌株产酶最佳培养基配方为:蔗糖7%,酵母膏0.7%,蛋白胨1.1%,MgSO4•7H2O 0.2%,柠檬酸三钠0.1%。使用优化后的培养基配方,醋杆菌C2的纤维素产量可达9.5g/L。     

Growth inhibition of Listeria spp. on Camembert cheese by bacteria producing inhibitory substances.

Bacterial strains exhibiting antimicrobial activity towards other bacteria are quite common in nature. During the past few years several genera have been shown to exert inhibitory action against Listeria. spp. In the present work strains of Enterococcus, Lactobacillus and Lactococcus were tested for their influence on the development of Listeria spp. on Camembert cheese. Partial or complete inhibition of growth of Listeria spp. was observed using various inhibitory bacteria. Complete inhibition occurred when the inhibitory strain was used as a starter culture and there was a low level of contamination with Listeria spp. during the first stage of ripening. Very little inhibition occurred if the inhibitory strain was added together with the starter culture.     

Calcium effect on mechanical properties of model cell walls and apple tissue

Bacterial cellulose alone, with pectin added and with both pectin and xyloglucan added were produced as models for plant cell walls. The artificial cell wall materials and natural apple tissue were treated with calcium and then subjected to tests of mechanical properties; a tension test for the artificial cell wall materials and a compression test for the apple tissue. It was found that pectin and xyloglucan had a significant effect on the mechanical properties of artificial cell wall materials, making them more extensible. A high concentration of calcium increased the failure strain and decreased the failure stress of these materials. Treatment of apple tissue with calcium had similar effects on the failure stress and the secant modulus, whereas the differences of failure strain and work to failure resulted in behaviour different from that of the artificial material.     

奶粉中一株阪崎肠杆菌的鉴定及其挥发性产物分析

目的鉴定奶粉中一株阪崎肠杆菌分离菌株F2-1,采用顶空气相色谱-质谱联用法(headspace gas chromatography-mass spectrometry,HS-GC-MS)分析分离菌株F2-1在液态培养中产生的挥发性代谢产物。方法应用VITEK 2 Compact全自动微生物鉴定系统分析分离菌株的生理生化特征;利用环介导等温扩增技术(loop-mediated isothermal amplification,LAMP)特异性扩增检测分离菌株的16S rDNA,通过HS-GC-MS分析分离菌株F2-1代谢的挥发性产物。结果分离菌株F2-1为革兰氏阴性菌,生理生化特征与阪崎肠杆菌(Enterobacter sakazakii,ES)的相似性为99%,LAMP检测进一步确认为阪崎肠杆菌,分离菌株F2-1在营养肉汤中代谢的挥发性产物主要有异戊醛、乙醇、异戊醇、3-羟基-2-丁酮、乙酸、正十五烷、正十六烷、正十七烷、1-癸醇。结论奶粉中分离菌株F2-1鉴定为阪崎肠杆菌,该菌产生的挥发性产物为阪崎肠杆菌的快速鉴定提供参考。     

1 株素食者产雌马酚肠道菌的分离与鉴定

以素食者粪便为样品,大豆异黄酮为底物,对产雌马酚的肠道菌进行分离培养及鉴定。采用紫外光谱法对雌马酚定性、定量测定,用肉眼观察、扫描电镜、生理生化、16S rDNA全序测序方法对分离得到的LJ-G1肠道菌进行菌株鉴定。结果表明：麦康凯和BHI培养基、厌氧平板划线培养法更适于产雌马酚肠道菌的分离筛选。采取10 g粪样稀释到10-5接种,在pH 7.3、温度37 ℃、厌氧培养36 h的条件下,培养基中雌马酚产出量达到10 μg/mL以上。经鉴定分离得到的LJ-G1菌株为G－杆菌;根据生理生化反应结果,查阅《常见细菌系统鉴定手册》,确定LJ-G1为河生肠杆菌;16S rDNA全序测序显示与肠杆菌同源性达99%。     

Challenges and advances in systems biology analysis of Bacillus spore physiology; molecular differences between an extreme heat resistant spore forming Bacillus subtilis food isolate and a laboratory strain

Bacterial spore formers are prime organisms of concern in the food industry. Spores from the genus Bacillus are extremely stress resistant, most notably exemplified by high thermotolerance. This sometimes allows surviving spores to germinate and grow out to vegetative cells causing food spoilage and possible intoxication. Similar issues though more pending toward spore toxigenicity are observed for the anaerobic Clostridia.The paper indicates the nature of stress resistance and highlights contemporary molecular approaches to analyze the mechanistic basis of it in Bacilli. A molecular comparison between a laboratory strain and a food borne isolate, very similar at the genomic level to the laboratory strain but generating extremely heat resistant spores, is discussed. The approaches cover genome-wide genotyping, proteomics and genome-wide expression analyses studies. The analyses aim at gathering sufficient molecular information to be able to put together an initial framework for dynamic modelling of spore germination and outgrowth behaviour. Such emerging models should be developed both at the population and at the single spore level. Tools and challenges in achieving the latter are succinctly discussed.     

南美白对虾养殖水体中抑藻细菌的分离及鉴定

本研究从南美白对虾养殖水体中分离出10株细菌,进行分子鉴定和系统进化树分析,并评价了它们对鱼腥藻Anabaena cylindricaFACHB-82的抑藻效果。16Sr RNA基因分析表明,分离的10株细菌中三株与假单胞菌Pseudomonas plecoglossicidc、Pseudomonas protegens和Pseudomonas monteilii最为相似,一株与气单胞菌Aeromonas veronii相似,两株与陶厄式菌Thauera mechernichensis和Thauera aromatica相似,枯草芽孢杆菌Bacillus subtilis、微杆菌Microbacterium flavum、黄杆菌Flavobacterium cauense以及金黄杆菌Chryseobacterium nakagawai各一株相似。抑藻结果表明细菌AB-3抑藻效果最好,其对鱼腥藻的生长抑制率达到87.11%。此外,AB-3菌对水华束丝藻Aphanizomenon flos-aquae和铜绿微囊藻Microcystis aeruginosa生长抑制率分别达到79.89%和23.65%,对小球藻Chlorella vulgaris也有一定的抑藻效果,但对衣藻Chlamydomonas reinhardtii抑藻效果不显著。本研究从水体中分离筛选出的一株陶厄氏菌AB-3,对试验的蓝藻都具有显著的抑藻效果,同时该菌对绿藻抑藻效果小或是没有抑制。