低温微生物在污水处理中的应用分析

低温微生物作为极端环境微生物研究的一大热点,自20世纪70年代以来,其研究应用就得到了越来越广泛的关注。低温微生物凭借一系列耐冷机制,可有效抵御低温对其细胞生存生长的胁迫,保障其在低温环境下仍能够生存繁殖。文章首先阐述了低温微生物的相关内涵及其适冷机制,然后探讨了低温微生物在污水处理中的实际应用,以期为低温微生物在实际生产生活中的应用提供参考。     

食品中低温微生物的适冷机制研究进展

低温贮藏是延长食品货架期、维持食品鲜度和质量安全的重要方法,然而仍有部分微生物能适应低温环境,使食品发生腐败变质。主要从细胞膜、适冷酶、冷休克蛋白、冷适应蛋白、代谢水平及低温防护剂等角度阐述国内外食品中低温微生物适冷机制的研究进展,为低温微生物在食品领域的应用与防护提供参考。     

微生物适冷酶及其应用研究新进展

生物圈的80%是由低温环境构成,大约90%的海水平均温度为5℃或者更低,这里孕育着极为丰富的微生物。根据微生物对环境温度的耐受性和其生长温度上限/下限的不同,将微生物分为嗜冷微生物和适冷微生物两大类。由这些微生物产生的适冷酶在低温下具有较高的催化效率和特异性,因而在生物技术领域具有巨大的应用潜力和开发价值。总结了近5年适冷酶新酶的筛选、发现及适冷酶稳定性的改造和低温表达系统等方面的最新研究进展,并对该领域的研究方向进行了展望。     

适冷微生物及其适冷机制研究进展

地球上许多生境为永久低温或季节性低温环境,适冷微生物在自然界中广泛存在。适冷微生物在环境净化、饲料、食品、奶制品、化妆品、皮革加工、洗涤等行业中具有广泛的应用前景。对适冷微生物的多样性、适冷的分子基础和适冷代谢机制进行了综述。     

低温酶及其冷适应性机制研究进展

生活在极地、深海等常年低温环境中的低温微生物和部分变温生物,能够通过产生低温酶来适应在低温环境中的生长、繁殖和代谢。这些酶在低温或常温条件下具有很高的催化活性,对热却很敏感,在高温时能够快速失活,因此在实际的生产和生活中具有广泛的应用前景。基于这些特性,低温酶的冷适应性机制研究成为了当前的一个热点。较系统地综述了低温酶的来源、特点、生产状况以及具有代表性的几种低温酶的冷适应性机制。     

低温微生物适应低温的分子机制

根据Ｍｏｒｉｔａ和Ｒｕｓｓｅｌ的定义 ,低温微生物可分为两类 :一类是其最高生长温度低于2 0℃的微生物称嗜冷菌 (ｐｓｙｃｈｒｏｐｈｉｌｅｓ) ,另一类是指在 0～ 40℃可以生长的微生物称耐冷菌 (ｐｓｙｃｈｒｏｔｒｏｐｈｓ)。这些微生物体内的温度与环境温度很接近。尽管低温对生化反应有着强烈的负效应 ,但低温微生物在低温下却能成功地生长与繁殖 ,它们因此产生了各种各样的适应机制 ,主要是细胞膜、蛋白质、酶分子水平上发生了精细的组成和结构的变化[1] ,因此弥补了低温对生长的有害影响。催化生物体内所有生化反应的酶是生物体适…     

适冷酶:性能与应用

由耐寒微生物产生的适冷酶显示出较高的催化活力,并常与热敏感性有关。运用X射线的结晶学理论,这一特性已开始逐渐为人所知,且控制它们对低温适应能力的机制各不相同。这些酶的应用为生物技术提供了巨大的发展潜力,例如在清洁剂和食品行业中用于生产精细化学品以及在生物环保处理中的应用。     

微生物对低温极端环境适应性的研究进展

嗜冷微生物是地球寒冷环境中最主要的生物类群,并且是驱动全球生物地球化学循环的关键环节。嗜冷微生物在适应策略上显示出应对多种极端环境因素的巨大潜力,研究其适应和进化机制有助于更好地理解微生物与环境之间相互作用过程,并有效利用极端环境微生物资源。近年来,随着分子生物学和基因组学技术的高速发展,对微生物适应寒冷环境的机制及嗜冷微生物在指示气候变化和工农业应用方面均有一系列的突破。在此,本文将从基因组的GC含量、蛋白质稳定性、转录翻译调控、细胞膜流动性、渗透压调节、抗氧化损失和基因组适应性进化等方面总结当前在微生物适应低温环境机制上所取得的进展,并展望低温环境微生物在指示气候变化和工农业应用中的前景。     

低温纤维素酶的研究进展

低温纤维素酶在低温下仍具有较高酶活力及较高催化效率,在应用中能够缩短处理工艺时间,节省加热或冷却费用,且易失活,有着中高温纤维素酶无法比拟的优势。现针对微生物低温纤维素酶的研究现状,包括菌种来源、分离鉴定、酶学性质、适冷结构及机理研究和基因工程等方面进行综述。     

低温微生物修复石油烃类污染土壤研究进展

耐冷菌、嗜冷菌等低温微生物广泛存在于极地、高山以及高纬度等土壤环境中,是石油烃类污染物在低温条件下降解与转化的重要微生物资源.利用低温微生物的独特优势,石油污染土壤的低温生物修复技术的研究成为当前热点领域.本文系统综述了低温石油烃降解菌的分类及冷适机制,低温微生物对不同类型石油烃组分的降解特征和降解机理,低温环境中接种降解菌、添加营养物质和表面活性剂等强化技术在石油污染土壤中生物修复的应用.以及微生物分子生物学技术在低温微生物降解石油烃的研究现状,为拓展我国石油污染土壤生物修复技术提供参考.     

Molecular basis of cold adaptation

Cold-adapted, or psychrophilic, organisms are able to thrive at low temperatures in permanently cold environments, which in fact characterize the greatest proportion of our planet. Psychrophiles include both prokaryotic and eukaryotic organisms and thus represent a significant proportion of the living world. These organisms produce cold-evolved enzymes that are partially able to cope with the reduction in chemical reaction rates induced by low temperatures. As a rule, cold-active enzymes display a high catalytic efficiency, associated however, with a low thermal stability. In most cases, the adaptation to cold is achieved through a reduction in the activation energy that possibly originates from an increased flexibility of either a selected area or of the overall protein structure. This enhanced plasticity seems in turn to be induced by the weak thermal stability of psychrophilic enzymes. The adaptation strategies are beginning to be understood thanks to recent advances in the elucidation of the molecular characteristics of cold-adapted enzymes derived from X-ray crystallography, protein engineering and biophysical methods. Psychrophilic organisms and their enzymes have, in recent years, increasingly attracted the attention of the scientific community due to their peculiar properties that render them particularly useful in investigating the possible relationship existing between stability, flexibility and specific activity and as valuable tools for biotechnological purposes.     

Cold active microbial lipases: some hot issues and recent developments

Lipases are glycerol ester hydrolases that catalyze the hydrolysis of triglycerides to free fatty acids and glycerol. Lipases catalyze esterification, interesterification, acidolysis, alcoholysis and aminolysis in addition to the hydrolytic activity on triglycerides. The temperature stability of lipases has regarded as the most important characteristic for use in industry. Psychrophilic lipases have lately attracted attention because of their increasing use in the organic synthesis of chiral intermediates due to their low optimum temperature and high activity at very low temperatures, which are favorable properties for the production of relatively frail compounds. In addition, these enzymes have an advantage under low water conditions due to their inherent greater flexibility, wherein the activity of mesophilic and thermophilic enzymes are severely impaired by an excess of rigidity. Cold-adapted microorganisms are potential source of cold-active lipases and they have been isolated from cold regions and studied. Compared to other lipases, relatively smaller numbers of cold active bacterial lipases were well studied. Lipases isolated from different sources have a wide range of properties depending on their sources with respect to positional specificity, fatty acid specificity, thermostability, pH optimum, etc. Use of industrial enzymes allows the technologist to develop processes that closely approach the gentle, efficient processes in nature. Some of these processes using cold active lipase from C. antarctica have been patented by pharmaceutical, chemical and food industries. Cold active lipases cover a broad spectrum of biotechnological applications like additives in detergents, additives in food industries, environmental bioremediations, biotransformation, molecular biology applications and heterologous gene expression in psychrophilic hosts to prevent formation of inclusion bodies. Cold active enzymes from psychrotrophic microorganisms showing high catalytic activity at low temperatures can be highly expressed in such recombinant strains. Thus, cold active lipases are today the enzymes of choice for organic chemists, pharmacists, biophysicists, biochemical and process engineers, biotechnologists, microbiologists and biochemists.     

低温微生物的冷适应机理及其应用

低温微生物广泛分布于极地、冰川、永久冻土和深海等寒冷环境,其冷适应能力是多种机理共同作用的结果,包括酶的低温催化活性、低温下膜流动性的保持、冷休克蛋白、抗冻蛋白以及抗冻保护剂等.低温微生物主要应用于催化低温发酵、表达热不稳定蛋白质、生产抗冻保护剂和冬季治理污水等领域.     

常温土壤中耐冷菌的分离、鉴定及产酶分析

目的:从常温土壤中筛选冷适应微生物,并进行初步鉴定和产低温酶分析。方法:采集吉首大学校园内土壤样品,通过低温富集培养筛选冷适应微生物;通过形态观察、生理生化特性检测和基于16S rRNA基因序列的系统发育分析,对分离的菌株进行初步鉴定;利用平板筛选法检测其产低温酶特性。结果:分离获得6株耐冷细菌JSBP-1～JSBP-6,初步鉴定其分属假单胞菌属(Pseudomonas)、紫色杆菌属(Janthinobacterium)和节杆菌属(Arthrobacter);在5℃和15℃培养条件下,菌株JSBP-1产蛋白酶能力较强,JSBP-2和JSBP-6产淀粉酶能力较强,JSBP-5仅在5℃条件下有较强的产脂肪酶特性。结论:常温土壤中存在一定数量的冷适应微生物,其中假单胞菌是其优势菌群之一。这类适冷微生物菌群具有潜在的生产低温酶能力。     

Toward a molecular understanding of cold activity of enzymes from psychrophiles

Despite the fact that a much greater proportion of the earth environment is cold rather than hot, much less is known about psychrophilic, cold-adapted microorganisms compared with thermophiles living at high temperatures. In particular, investigation of the molecular basis of cold-active enzymes from psychrophiles has only recently received concerted research attention, in measure as a result of the EC-funded project COLDZYME. This research effort has been stimulated by the realization that such cold-active enzymes offer novel opportunities for biotechnological exploitation. Only very recently has the first cold-active enzyme, α-amylase, been crystallized, and this success was followed rapidly by others. This effort has facilitated a direct approach to solving the three-dimensional structure of cold-active enzymes to complement the gene homology modeling that had been performed previously. Recently studies have highlighted how different adaptations are used by different enzymes to achieve conformational flexibility at low temperatures, and how such adaptations are not necessarily the opposite of those that confer thermostability to proteins in thermophilic counterparts. This review also highlights initial successes in engineering genetically improved thermal stability in cold-active enzymes to give improved catalysts for low-temperature biotechnology. Received: July 11, 1999 / Accepted: December 27, 1999     

Psychrophilic yeasts from worldwide glacial habitats: diversity, adaptation strategies and biotechnological potential

Glacial habitats (cryosphere) include some of the largest unexplored and extreme biospheres on Earth. These habitats harbor a wide diversity of psychrophilic prokaryotic and eukaryotic microorganisms. These highly specialized microorganisms have developed adaptation strategies to overcome the direct and indirect life-endangering influence of low temperatures. For many years Antarctica has been the geographic area preferred by microbiologists for studying the diversity of psychrophilic microorganisms (including yeasts). However, there have been an increasing number of studies on psychrophilic yeasts sharing the non-Antarctic cryosphere. The present paper provides an overview of the distribution and adaptation strategies of psychrophilic yeasts worldwide. Attention is also focused on their biotechnological potential, especially on their exploitation as a source of cold-active enzymes and for bioremediation purposes.     

Psychrophilic and psychrotrophic fungi: a comprehensive review

This article reviews the comparative diversity of psychrophilic and psychrotrophic fungi, their adaptability mechanisms for survival and potential applications in biotechnology and pharmaceuticals. Fungi are able to grow and survive at low temperature and exist widely in polar and non-polar habitats. These cold regions are known for very low temperature, high ultra violet-B radiation, frequent freeze and thaw cycles and low water and nutrient availability. Most of the fungi adapt to such harsh conditions by evolving various strategies in their metabolism and physiology. Psychrophilic and psychrotrophic fungi are of importance in biotechnological and pharmaceutical fields due to their diverse characteristics developed or evolved due to their adaptation and survival in extreme environments, like; production of cold-active enzymes, pharmaceutical or bioactive metabolites and exo-polysaccharides, have potential for bioremediation and can also be used as biofertilizer.