极端微生物：一种新型的酶资源

极端微生物具有自身独特的特点和代谢产物 ,在食品工业、化工、药用工业和环境生物技术领域都有潜在的应用。一些酶已经得到纯化 ,其基因在宿主中已成功克隆。主要介绍和讨论极端微生物的类型、基因组及极端酶类的生产、分离与应用。     

乳酸菌在食品工业中的运用研究

乳酸菌是一种非常安全的微生物，其不仅能维持人体微生物系统的平衡，而且能帮助机体降低血脂、血压和抑制癌症，乳酸菌的这种生物学功能也使其在食品行业应用领域被不断开拓。文章从乳酸菌的分类和安全性出发，分析了乳酸菌在食品工业中应用的功能，介绍了乳酸菌在食品工业中的具体运用。     

开辟制药新天地——转基因微生物撰文崔艳孟志刚

正转基因微生物的商业化主要应用在食品工业、医药、饲料业以及农业杀虫剂等方面,尤其在医药领域的应用更是日益广泛。在传统的药物生产中,有些药品与疫苗最初是直接从生物的组织、细胞或血液中提取而来的,因为受到原     

现代生物技术在食品领域的应用

以分子生物学为基础的现代生物技术是当今食品科技和产业发展的主要驱动力,现已广泛应用于食品工业,未来在食品领域也将发挥举足轻重的作用。文章主要从食品原料改良、发酵菌种改造、发酵食品微生物菌群多样性解析及食品安全检测等方面介绍了现代食品生物技术在食品相关领域的应用,为现代生物技术在食品领域的应用提供参考。     

微生物谷氨酰胺转胺酶研究进展

微生物谷氨酰胺转胺酶是一种在食品、医药、纺织、化妆品等领域具有广泛应用前景的酶制剂。就其理化性质、作用机理、工业化生产、在食品工业上的应用及当前国内外研究热点进行了概述。并讨论了微生物谷氨酰胺转胺酶在我国生产及应用中存在的问题和困难,对未来的研究方向做出展望。     

微生物产生的生物表面活性剂及其应用研究

对生物表面活性剂的类型及其产生微生物,生物表面活性剂的生产和生物表面活性剂在石油开采、食品工业、农业、药品和化妆品以及环境保护等领域的潜在应用价值作了介绍,展现出了生物表面活性剂的广阔应用前景。     

电化学法快速检测微生物的发展现状及趋势

自1898年Stewart提出利用电化学法检测微生物,电化学法已发展成为一种微生物快速检测的方法。根据检测的参数不同,电化学微生物检测法可以分为阻抗微生物法和介电常数法。阻抗法主要用于食品工业中微生物的快速检测(≤10⁷ cfu/mL),尤其用于易腐食品的微生物快速检测,以期实现在其发生明显腐败之前得到检测结果。而介电常数则用于生物发酵过程中的微生物数量的快速测定,可以实现在线监测微生物数量及生物发酵过程的实时控制。电化学法由于其检测迅速、可以实现自动化检测,在工业化生产中具有广阔的应用前景。     

微生物源天然防腐剂在食品上的应用研究

微生物源天然防腐剂是理想的天然食品防腐剂,具有安全、无毒、高效、无副作用的特点,符合未来食品防腐的发展与使用要求,在食品工业中的应用越来越广泛.该文对天然微生物源防腐剂的来源分类、抑菌特性、抑菌机理及适用范围进行了系统的研究分析与论述.有针对性地对目前两种应用最为广泛的微生物源天然防腐剂乳酸链球菌素和纳他霉素予以介绍,同时对微生物源天然防腐剂使用过程中遇到的问题提出了对策建议.对天然防腐剂的应用与发展具有现实和指导意义.     

溶菌酶的研究进展

溶菌酶普遍存在于动物、植物和微生物中。溶菌酶是一种小分子碱性蛋白,长期以来一直被作为一种“模型”体系．用于研究蛋白质的空间构象、酶动力学及其与分子进化、分子免疫间的关系。介绍了溶菌酶的来源、结构、性质、作用机制。并对近年来其在食品工业、医学和酶工程中的应用进行了综述;分析了溶菌酶应用中存在的主要问题,并对其应用前景进行了展望。     

微生物生物膜研究的新进展

微生物在生长过程中为适应生存环境而形成了生物膜,Dr.Costerton JW在生物膜方面的研究为我们开拓了微生物学的新领域。微生物生物膜是由微生物群体及其包被的细胞外多聚物和基质网组成,它们彼此黏附或者黏附到组织或物体的表面。微生物生物膜与微生物的耐药性形成、基因的转移以及引起机体的持续性感染等都密切相关。目前对生物膜的研究重点已经深入到微生物相互间的信号传递、致病基因的转移以及如何干预微生物生物膜的形成等方面。此外,在治理污水和环境保护工程、生物材料工程和食品工业等方面,微生物生物膜技术已经得到了应用。     

Comparative and Experimental Approaches to the Study of Microbial Food Webs

ABSTRACT The study of microbial food webs is dominated by field measurements of microbial standing stocks and rate processes and to a lesser extent by laboratory studies. These approaches reflect the concerns of microbial ecologists to assess accurately the capabilities of microorganisms and to compare microbial processes to other ecosystem parameters. These approaches have led to enormous advances in understanding microbial food webs. Reconciling our expanding knowledge with general questions about the significance and representation of microbial food webs in ecosystem studies requires additional approaches including comparative studies and field experiments. Comparative studies, analyses of microbial stocks or rates across a wide range of ecosystems, lead to quantitative models of microbial processes. These models facilitate testing of hypotheses at a very general level, allow the comparison of different stocks or rate processes across a gradient of systems, and detect unusual situations or outlier systems. Field experimental manipulations offer the advantages of working with intact natural communities, of direct evaluation of results with statistical methods, and of testing important qualitative hypotheses. Both comparative and field manipulation studies have led to important advances in the study of microbial food webs and should be expanded.     

The role of fungi in the nutrition of stream invertebrates

Dead leaves falling into streams are an important food source for many invertebrates. They are generally made more palatable and more nutritious if they are first colonized by aquatic hyphomycetes and other micro-organisms. At least two mechanisms appear to be responsible for this conditioning effect: microbial production (addition of easily digested microbial compounds to the nutritionally poor leaf substrate), and microbial catalysis (conversion of indigestible leaf substances into digestible subunits by microbial enzymes). Different invertebrate species vary in their ability to take advantage of microbial conditioning. This appears to be influenced by their mobility, the range of their food resources and their ability to overcome defense mechanisms of leaf-colonizing microorganisms.     

Above‐ and belowground linkages in Sphagnum peatland: climate warming affects plant‐microbial interactions

Peatlands contain approximately one third of all soil organic carbon (SOC). Warming can alter above‐ and belowground linkages that regulate soil organic carbon dynamics and C‐balance in peatlands. Here we examine the multiyear impact of in situ experimental warming on the microbial food web, vegetation, and their feedbacks with soil chemistry. We provide evidence of both positive and negative impacts of warming on specific microbial functional groups, leading to destabilization of the microbial food web. We observed a strong reduction (70%) in the biomass of top‐predators (testate amoebae) in warmed plots. Such a loss caused a shortening of microbial food chains, which in turn stimulated microbial activity, leading to slight increases in levels of nutrients and labile C in water. We further show that warming altered the regulatory role of Sphagnum‐polyphenols on microbial community structure with a potential inhibition of top predators. In addition, warming caused a decrease in Sphagnum cover and an increase in vascular plant cover. Using structural equation modelling, we show that changes in the microbial food web affected the relationships between plants, soil water chemistry, and microbial communities. These results suggest that warming will destabilize C and nutrient recycling of peatlands via changes in above‐ and belowground linkages, and therefore, the microbial food web associated with mosses will feedback positively to global warming by destabilizing the carbon cycle. This study confirms that microbial food webs thus constitute a key element in the functioning of peatland ecosystems. Their study can help understand how mosses, as ecosystem engineers, tightly regulate biogeochemical cycling and climate feedback in peatlands     

一种改进的普洱茶固态发酵过程微生物DNA提取方法

为开发一种改进的普洱茶固态发酵过程微生物DNA提取方法,首先配制含有吐温-20、聚乙烯吡咯烷酮(PVP)、乙二胺四乙酸二钠(Na2EDTA)等组分的洗涤缓冲液,引入超声波振荡、涡旋、65℃水浴、反复洗涤等手段,把普洱茶发酵微生物较高质量的收集起来,再使用十六烷基三甲基溴化铵(CTAB)法提取微生物总DNA。按照本文所述方法所得到的菌体沉淀接近白色,后续提取出的DNA总量高、色度低、杂质少,适用于PCR及基因组学等研究。     

Recent findings in pulsed light disinfection

Nonthermal disinfection technologies are gaining increasing interest in the field of minimally processed food in order to improve the microbial safety or to extend the shelf life. Especially fresh‐cut produce or meat and fish products are vulnerable to microbial spoilage, but, due to their sensitivity, they require gentle preservation measures. The application of intense light pulses of a broad spectral range comprising ultraviolet, visible and near infrared irradiation is currently investigated as a potentially suitable technology to reduce microbial loads on different food surfaces or in beverages. Considerable research has been performed within the last two decades, in which the impact of various process parameters or microbial responses as well as the suitability of pulsed light (PL) for food applications has been examined. This review summarizes the outcome of the latest studies dealing with the treatment of various foods including the impact of PL on food properties as well as recent findings about the microbicidal action and relevant process parameters.     

Population- and ecosystem-level effects of predation on microbial-feeding nematodes

We studied the role of nematode predation in the functioning of detrital food webs assembled in microcosms. The microcosms contained defaunated humus and litter materials, a diverse microbial community with bacteria, fungi and protozoa, and a birch (Betula pendula) seedling infected with mycorrhizal fungi. Different levels of top-down control upon microbivorous nematodes were set up by assembling food webs either without predators, or in combinations with a specialist and a non-specialist predatory mite (Mesostigmata). The nematode community was composed of either (1) three species of bacterivorous, or (2) three species of fungivorous nematodes or (3) both groups together. After two growing periods for the birch (38 weeks), the microcosms were destructively sampled for animal and microbial biomasses, concentration of mineral N in the soil, plant biomass and plant N concentration. The specialist predator reduced biomasses of both bacterial- and fungal-feeding nematodes by more than 50%, whereas the non-specialist predator weakly increased the biomass of fungivorous nematodes. Thus, under high predation pressure, the biomass of microbivores changed as predicted by trophic dynamic models assuming strong top-down control and uniformly behaving trophic levels. Despite this, microbial biomass was unaffected by the predators. However, microbial respiration increased slightly in the presence of predators. Assuming that microbial respiration correlates with microbial productivity, the increase in microbial respiration indicates a cascading productivity regulation. The composition of the microbivore community had only a minor effect on the outcome of the top-down control on microbes. The >50% reduction in nematode biomass and respiration coincided with <16% increase in microbial respiration and did not affect microbial biomass. Presence of the specialist predator slightly reduced soil NH⁺ ₄ concentration in communities with fungivore nematodes but plant growth and N uptake remained unchanged. Thus, the structure of the community only weakly controlled nutrient mineralisation. Received: 18 May 1998 / Accepted: 3 May 1999     

Structure of planktonic microbial food web in a brackish stratified Siberian lake

The distribution of primary components of the microbial community (autotrophic pico- and nanoplankton, phototrophic bacteria, heterotrophic bacteria, microscopic fungi, heterotrophic flagellates, ciliates and heliozoa) in the water column of Lake Shira, a steppe brackish-water, stratified lake in Khakasia, Siberia (Russia), were assessed in midsummer. Bacterioplankton was the main component of the planktonic microbial community, accounting for 65.3 to 75.7% of the total microbial biomass. The maximum concentration of heterotrophic bacteria were recorded in the monimolimnion of the lake. Autotrophic microorganisms contributed more significantly to the total microbial biomass in the pelagic zone (20.2–26.5%) than in the littoral zone of the lake (8.7–14.9%). First of all, it is caused by development of phototrophic sulphur bacteria at the oxic-anoxic boundary. The concentrations of most aerobic phototrophic and heterotrophic microorganisms were maximal in the upper mixolimnion. Heterotrophic flagellates dominated the protozoan populations. Ciliates were minor component of the planktonic microbial community of the lake. Heterotrophic flagellates were the most diverse group of planktonic eucaryotes in the lake, which represented by 36 species. Facultative and obligate anaerobic flagellates were revealed in the monimolimnion. There were four species of Heliozoa and only three of ciliates in the lake.     

Inulin-type fructans of longer degree of polymerization exert more pronounced in vitro prebiotic effects

AIMS: We assessed to what extent fructans of different degrees of polymerization (DP) differ in their prebiotic effectiveness towards in vitro microbial communities from the proximal and distal colon. METHODS AND RESULTS: Two short chain fructans - oligofructose (DP 2-20) and inulin (DP 3-60) - were administered to the Simulator of the Human Intestinal Microbial Ecosystem (SHIME) at 2.5 g day(-1). The influence of fructan addition towards fermentation activity and microbial community composition from the different SHIME colon compartments were evaluated. Both fructans exerted prebiotic effects with significantly higher butyrate and propionate production and stimulation of lactic acid-producing bacteria. Compared with oligofructose, it was noted that it took more time before significant effects from inulin addition were observed. Yet, the higher short-chain fatty acid production and lower proteolytic activity showed that the prebiotic effects from inulin were more pronounced than oligofructose. Also, the bifidogenic effects from inulin vs oligofructose were higher in the distal colon compartments and this effect was prolonged in the distal colon once the addition was stopped. CONCLUSIONS: Inulin has more pronounced prebiotic effects than oligofructose towards both fermentation activity and bacterial community composition in the SHIME model. SIGNIFICANCE AND IMPACT OF THE STUDY: Its slower fermentation rate and higher prebiotic potency makes inulin a more interesting compound than oligofructose to beneficially influence the microbial community from both the proximal and distal colon regions.     

Fatty acid analysis and spoilage potential of biofilms from two breweries

AIM: The microbial composition of biofilms from different locations of beer bottling plants were compared based on fatty acid profiles and correlated with the product-spoiling potential of these biofilms. METHODS AND RESULTS: The whole cell fatty acid profiles of 78 biofilms from bottling plants of two breweries were analysed. About half of the lipid profiles were dominated by oleic and linoleic acid, which refer to a high proportion of yeasts. In addition, more than half of all samples contained dimethylacetals indicating the presence of strictly anaerobic bacteria. Typical fatty acids for potentially beer-spoiling genera were detected in three biofilms. The majority of the biofilms contained no beer-spoiling organisms, as shown by inoculation experiments in beer. CONCLUSIONS: Biofilms from different locations of bottling plants were different with respect to their microbial composition. Potentially product-spoiling populations could be detected in a small number of samples. SIGNIFICANCE AND IMPACT OF THE STUDY: Biofilms on industrial plants can be characterized by a fast and cultivation-independent method with respect to overall microbial composition and presence of potentially product-spoiling micro-organisms.     

Microbial transglutaminase: An overview of recent applications in food and packaging

Abstract

The glue of proteins, microbial transglutaminase (MTG) has been adopted in the food processing industries for its broad enzymatic action. Microorganisms such as Streptoverticillium and Streptomyces are the major sources, to decrease the cost of manufacturing animal origin transglutaminase. The net % increase of its demands in the food processing is estimated at 21.9% per year. In fact, MTG is consumed by most food industries, spanning the meat, dairy, seafood and fish, plant proteins, edible film preparation and more. It used to improve gelation and change foaming, emulsification, viscosity, consistency and water-holding capacity properties. This paper presents an overview of the literature that described and explored the recent microbial origins, production media and applications of microbial transglutaminase.