1株聚乙烯醇降解菌的分离鉴定及其降解性能

筛选聚乙烯醇（PVA）降解性能优良且适合驯化的菌种是PVA生物降解的关键环节。为了获取PVA高效降解菌种,采用选择性培养基从某化工厂回流池污泥中筛选菌株,并对菌株的生长及PVA降解过程、培养液pH值、温度、摇床转速、装液量进行测定。结果表明：筛选的1株聚乙烯醇高效降解菌MH 007,基于16S rRNA基因序列的系统发育多样性分析鉴定该菌为Sphingopyxis terrae的一个菌株。该菌PVA降解率可达97.2%,摇床动态培养过程中降解PVA的最佳条件为pH 7.2、温度30 ℃、摇床转速120 r/min和30%的装样量。     

聚乙烯醇的生物降解

聚乙烯醇(PVA)是较少的可溶于水并被生物降解的乙烯聚合物之一。研究表明,在受PVA污染的自然环境中存在着能降解PVA的微生物,并从中提取出了PVA降解酶。介绍了国内外研究聚乙烯醇生物降解的情况。分别讨论了聚乙烯醇被单一菌种、共生细菌和真菌降解过程中的生物化学和生理学特性,以及结构因素对聚乙烯醇生物降解的影响。这些研究促进了可有效生物降解的PVA类材料产品项目的发展。     

蜡样芽孢杆菌聚乙烯醇脱氢酶的表达及酶学特性

【背景】聚乙烯醇脱氢酶(polyvinyl alcohol dehydrogenase,PVADH)能够使聚乙烯醇(polyvinyl alcohol,PVA)氧化脱氢,在PVA的生物降解过程中起到重要作用。【目的】从PVA降解菌株蜡样芽孢杆菌DG01中获取pvadh基因,实现PVADH在毕赤酵母中的异源表达并探究其对不同型号PVA的降解特异性,为PVADH在PVA实际降解中的应用提供指导。【方法】通过反转录扩增技术获得长度为1 965 bp的pvadh基因片段,构建pPIC9K-cpvadh重组表达质粒并在毕赤酵母GS115中实现异源表达,甲醇诱导表达蛋白,进行分离纯化后对其酶学性质及降解特异性进行研究。【结果】最佳发酵条件下PVADH粗酶液酶活达到54.55 U/mL。经分离纯化后表达蛋白PVADH的比酶活为173.42 U/mg,分子量为67.1 kDa,等电点为6.06,该酶最适作用温度为41℃,最适作用pH值为7.5,在27-32℃、pH 7.0-8.0条件下酶的半衰期超过4 h,1 mmol/L的Ca2+对酶活力有激活作用。PVADH分别作用于PVA1788、PVA1799...     

聚乙烯醇高效降解菌的筛选及降解特性研究

以聚乙烯醇为唯一碳源从环境中筛选获得了高效降解聚乙烯醇的微生物菌株XT11, 初步鉴定为假单胞菌属(Pseudomonas sp.)。对菌株Pseudomonas XT11的生长过程及PVA降解过程进行了研究, 发现该菌株在54 h内可将1 g/L的聚乙烯醇(PVA)降解。同时研究了温度、pH值及酵母膏浓度对该菌株降解PVA的影响, 结果表明其最适温度、pH值和酵母膏浓度分别为30℃、7.0和0.5 g/L。研究了PVA浓度对PVA降解率的影响, 发现随着PVA浓度的增大, PVA的降解率降低。     

聚乙烯醇高效降解菌的筛选及降解特性研究

以聚乙烯醇为唯一碳源从环境中筛选获得了高效降解聚乙烯醇的微生物菌株XT11,初步鉴定为假单胞菌属(Pseudomonas sp.).对菌株Pseudomonas XT11的生长过程及PVA降解过程进行了研究,发现该菌株在54 h内可将1 g/L的聚乙烯醇(PVA)降解.同时研究了温度、pH值及酵母膏浓度对该菌株降解PVA的影响,结果表明其最适温度、pH值和酵母膏浓度分别为30℃、7.0和0.5 g/L.研究了PVA浓度对PVA降解率的影响,发现随着PVA浓度的增大,PVA的降解率降低.     

影响青霉产聚乙烯醇降解酶营养因素的研究

在培养基中没有聚乙烯醇 (PVA)及有PVA存在的情况下 ,考察了酵母粉、2 0种氨基酸和部分维生素对一株青霉WSH0 2 2 1产PVA降解酶的影响。当培养基中无PVA时 ,以酵母粉为氮源时 ,该菌株可产生 38 9U L的PVA降解酶 ;加入PVA后 ,酶活提高了 3 3倍 ,表明该菌株所产的PVA降解酶是可诱导的。进一步研究发现 ,不管培养基中是否存在PVA ,若没有苏氨酸存在 ,该菌株正常生长 ,但不能产生PVA降解酶 ,表明苏氨酸是该菌株产生PVA降解酶所必需的 ,而非生长所必需。在苏氨酸添加浓度为 10mg L到 2 0mg L的范围内 ,该菌株所产PVA降解酶的酶活随着培养基中苏氨酸浓度的增大而呈现上升趋势。     

快速筛选聚乙烯醇降解菌的简便方法

本文介绍的快速筛选聚乙烯醇(PVA)降解菌的简便方法是,将待测样品分别点种在PVA作碳源制备的固体平板上。30℃培养3天后,加显色荆观察:呈现无色透明斑者为阳性菌;呈现蓝绿色者为阴性菌。     

褐腐真菌木质纤维素降解机制的研究进展

褐腐菌降解木才机理的研究日前受到关注,发现褐腐菌不具有对结晶纤维素降解十分重要的外切葡聚糖酶,而以一种独特的方式解降纤维素。近年来,关于其以自由基氧化降解机制进行作用的报道很多,并且各国研究工作从褐腐菌中分离得到了不同性质的物质,提出了羟基自由基HO．循环形成的各种假说,但褐腐菌降木材的确切机制仍未搞清楚,这些分离得到的具有一些特殊性质的胞外物质在降解中的作用还有待于证明,在此。对近年来褐腐菌纤维素降解机制的研究进展作一简单介绍。     

多氯联苯降解菌Burkholderia xenovorans LB400研究进展

Burkholderia xenovorans LB400是一株多氯联苯(polychlorinated biphenyls,PCBs)降解菌,可以氧化含有1?6个氯取代基的多氯联苯。近年来,由于其广泛的底物谱和优异的降解性能,菌株LB400已成为研究原核生物降解多氯联苯的生物化学和分子生物学方面的模式生物。目前关于PCBs的微生物降解研究已不再局限于对微生物资源的挖掘,而是更多地聚焦在LB400等降解菌的PCBs降解基因、降解酶的酶学特性以及酶的人工分子进化等方面。同时,LB400作为早期发现的降解菌,其对多氯联苯的降解途径、底物范围及相关机制也被广泛探讨;但是对于PCBs降解相关基因的调控研究较少。因此,本文以Burkholderia xenovorans LB400对多氯联苯降解为核心,通过综述其代谢途径、代谢相关基因和酶系以及降解应用等方面的研究进展,以期为深入探讨Burkholderia xenovorans LB400的应用以及进一步在遗传、分子和生化水平研究其他多氯联苯降解菌株提供借鉴。     

褐腐真菌木质纤维素降解机制的研究进展*

褐腐菌降解木材机理的研究日益受到关注 ,发现褐腐菌不具有对结晶纤维素降解十分重要的外切葡聚糖酶 ,而以一种独特的方式降解纤维素。近年来 ,关于其以自由基氧化降解机制进行作用的报道很多 ,并且各国研究工作者从褐腐菌中分离得到了不同性质的物质 ,提出了羟基自由基HO·循环形成的各种假说 ,但褐腐菌降解木材的确切机制仍未搞清楚 ,这些分离得到的具有一些特殊性质的胞外物质在降解中的作用还有待于证明。在此 ,对近年来褐腐菌纤维素降解机制的研究进展作一简单介绍。     

Application of enzymes for textile fibres processing

This review highlights the use of enzymes in the textile industry, covering both current commercial processes and research in this field. Amylases have been used for desizing since the middle of the last century. Enzymes used in detergent formulations have also been successfully used over the past 40 years. The application of cellulases for denim finishing and laccases for decolourization of textile effluents and textile bleaching are the most recent commercial advances. New developments rely on the modification of natural and synthetic fibres. Advances in enzymology, molecular biology and screening techniques provide possibilities for the development of new enzyme-based processes for a more environmentally friendly approach in the textile industry.     

Degradation of polyvinyl alcohol by <Emphasis Type="Italic">Sphingomonas</Emphasis> sp. SA3 and its symbiote

A total of 800 samples was taken from Taegu province, Korea, where many textile factories provide a source of polyvinyl alcohol (PVA) waste. These samples were screened for PVA-degrading bacteria. A new strain, SA3, was discovered which formed yellow colonies and used PVA as the sole carbon and energy source. Strain SA3 was identified as a Sphingomonas sp., based on the partial nucleotide sequence analysis of 16S ribosomal RNA, the presence of 2-hydroxymyristic acid (14:O 2-OH) and sphingolipids with d-17:0, d-18:0, d-19:1, and d-20:1 as the main dihydrosphingosines. This genus has not previously been reported as a PVA-degrading bacterium. Sphingomonas sp. SA3 needs a symbiote strain, SA2, for PVA degradation as a growth factor producer. In mixed cultures of these strains, the optimum temperature for PVA biodegradation ranged from 30 °C to 35 °C. The optimum pH was 8.0 and the most effective nitrogen source was NH₄ ⁺. Electronic Publication     

Production of polyvinyl alcohol-degrading enzyme with Janthinobacterium sp. and its application in cotton fabric desizing

A strain capable of using polyvinyl alcohol (PVA) as sole carbon source was isolated from soil samples of a textile factory. The 16S rDNA sequence analysis cell morphology, physiology and biochemistry showed that it belonged to Janthinobacterium sp. This is the first report to show that the screened Janthinobacterium sp. could degrade PVA. The optimum nutritional and environmental conditions for PVA-degrading enzyme production by Janthinobacterium sp. were investigated by single-factor tests. Under optimized nutritional and environmental condition in shake flasks, PVA-degrading enzyme reached 5.12 U/mL at 21 h. With PVA-degrading enzyme produced by Janthinobacterium sp. WSH04-01, 80% of PVA could be degraded from cotton fabrics in 3 h.     

Effects and statistical optimization of fermentation conditions on growth and poly (vinyl alcohol)-degrading enzyme production of Streptomyces venezuelae GY1

The effects of environmental conditions, including temperature, pH and dissolved oxygen, on growth and production of polyvinyl alcohol (PVA)-degrading enzymes of the newly-isolated strain Streptomyces venezuelae GY1 were investigated. The medium composition for strain GY1 was studied first by single factorial design and then optimized using a central composite design. PVA with high saponification is better for growth of, and PVA-degrading enzyme production by S. venezuelae GY1 compared with PVA with low saponification, in contrast with the characteristics of other bacteria producing PVA-degrading enzymes. The optimal temperature and initial pH for production of PVA-degrading enzyme by strain GY1 was 30°C and 7.0, respectively. The optimal medium composition for PVA-degrading enzyme production is: 1.01 g L^?1 of PVA1799, 0.307 g L^?1 of NaNO₃ and 0.512 g L^?1 of MgSO₄?7H₂O.     

Biodegradation of polyvinyl alcohol by a mixed microbial culture

A mixed culture capable of degrading 1 g l⁻¹ polyvinyl alcohol (PVA) completely was screened from sludge samples at Pacific Textile Factory, Wuxi, China. This mixed culture had stronger capability of degrading PVA with low polymerization and high saponification than degrading PVA with high polymerization and low saponification. Inorganic nitrogen source was more suitable for the mixed culture to grow and degrade PVA than organic nitrogen source. Microorganisms and relative abundance of this mixed culture were explored by terminal restriction fragment length polymorphism (T-RFLP). Small PVA molecules were detected in cell extracts of the mixed culture. This indicated that PVA degradation in the mixed culture was in fact a combined action of extracellular and intracellular enzymes. Two strains producing extracellular PVA-degrading enzyme were isolated from the mixed culture. They could individually degrade PVA1799 with polymerization of 1700 from initial average molecular weight 112,981 to 98,827 Da and 84,803 Da, respectively. However, only small amount of PVA124 in polymerization of 400 could be degraded by these two strains.     

Isolation and Culture Characterization of a New Polyvinyl Alcohol-Degrading Strain: Penicillium sp. WSH02-21

A fungal strain able to grow on polyvinyl alcohol (PVA) as sole carbon source was isolated from activated sludge of a textile factory. Morphological characteristics showed that this strain belonged to Penicillium sp., and, to our knowledge, this is the first report of PVA degradation by a strain of Penicillum sp. When 0.5% PVA was used as the carbon source in culture medium, it could be completely degraded after 12 days. This strain was found to produce and secrete an inducible PVA-degrading enzyme. High PVA concentration and oxygen transfer were favourable for PVA-degrading enzyme synthesis by Penicillium sp. cultured in shake-flasks. Moreover, Penicillum sp. cultured in PVA medium may spontaneously produce more catalase to decompose H₂O₂, a product of PVA oxidation by PVA oxidase, for protection of the cells from H₂O₂ damage. This revised version was published online in July 2006 with corrections to the Cover Date.     

Biochemistry of microbial polyvinyl alcohol degradation

Effect of minor chemical structures such as 1,2-diol content, ethylene content, tacticity, a degree of polymerization, and a degree of saponification of the main chain on biodegradability of polyvinyl alcohol (PVA) is summarized. Most PVA-degraders are Gram-negative bacteria belonging to the Pseudomonads and Sphingomonads, but Gram-positive bacteria also have PVA-degrading abilities. Several examples show symbiotic degradation of PVA by different mechanisms. Penicillium sp. is the only reported eukaryotic degrader. A vinyl alcohol oligomer-utilizing fungus, Geotrichum fermentans WF9101, has also been reported. Lignolytic fungi have displayed non-specific degradation of PVA. Extensive published studies have established a two-step process for the biodegradation of PVA. Some bacteria excrete extracellular PVA oxidase to yield oxidized PVA, which is partly under spontaneous depolymerization and is further metabolized by the second step enzyme (hydrolase). On the other hand, PVA (whole and depolymerized to some extent) must be taken up into the periplasmic space of some Gram-negative bacteria, where PVA is oxidized by PVA dehydrogenase, coupled to a respiratory chain. The complete pva operon was identified in Sphingopyxis sp. 113P3. Anaerobic biodegradability of PVA has also been suggested.     

Research and application of biotechnology in textile industries in China

Textile industry is a conventional and pillar industry in China, which possesses a considerable proportion of the national economy. In recent years, special attention has been paid to the application of biotechnology in textile industries in China. As an interdiscipline between natural science and engineering science, textile biotechnology has much effect on China's textile industry. This paper summarizes current developments and highlights those areas where biotechnology might play an increasingly important role in China's textile industry as follows:

(1) Development of new types of textile fibers and polymers, such as Bt cotton naturally colored cotton, colored silk and silk gene-sequence, spider silk non-wovens, chitin fiber and chitosan derivatives, etc.

(2) Application of enzyme technology in textile wet processing, such as alkaline pectinase, PVA-degrading enzyme, cutinase and catalase used for cotton preparation, neutral cellulase for denim washing, transglutaminase for wool modification, protease for silk degumming as well as pectinase and hemicellulases for retting of bast fibers.

(3) Treatment of textile effluents with biotechnology.

Properties and roles of bacterial symbionts of polyvinyl alcohol-utilizing mixed cultures

From several polyvinyl alcohol (PVA)-utilizing mixed cultures, two component bacterial strains essential for PVA utilization were isolated, and their properties and roles in PVA utilization were studied. Each pair of essential component strains consisted of a type I strain, which produced a PVA-degrading enzyme and constituted the predominant population of the mixed culture in PVA, and a type II strain, which produced a certain growth stimulant for the former strain. All of the type I strains were taxonomically identical and assigned as Pseudomonas sp. In contrast, type II strains were taxonomically different from each other, belonging to Pseudomonas spp. and Alcaligenes sp. PVA utilization occurred in each mixed culture of a type I strain with Pseudomonas putida VM15A as a substitute for the type II strain of the original pair and also in each mixed culture of a type II strain with Pseudomonas sp. VM15C. The growth rates of these substituted, mixed cultures differed from each other.