聚乙烯醇生物降解研究进展

聚乙烯醇(PVA)是一种在纺织和化工行业中广泛使用的难降解的高分子聚合物。随着人们对纺织工业清洁生产的关注,如何在退浆工艺中就实现对PVA的生物降解、减少PVA废水的排放,并避免化学退浆过程中高温和氧化造成的棉纤维损伤,是近年来纺织生物技术领域的研究热点。由于PVA降解菌种类不多、培养周期长,PVA降解酶酶活不高、提取不容易等原因,使PVA的生化降解研究还局限在PVA降解菌的筛选、PVA降解酶的酶学性质研究等方面,PVA降解酶还未在纺织工业上得到应用。本文综述了近年来国内外在PVA降解菌筛选、PVA降解酶提取及酶学性质、PVA生化降解机理等方面的研究进展,并讨论了PVA生化降解研究中存在的问题及发展方向。     

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。     

环境保护及农业废物利用

952S16分子量和有规立构性对粪产碱菌生物降解聚乙烯醇的影响[英]/Matsumura,S.…,Biotechn01.Lett.一1994,16(11).一1205～1210[译自DBA,1995,14(2),95—01266] 利用降解PVA的粪产碱菌KK314(用PVA一1:3000作唯一碳源)和同化PVA的共生菌(PVA—IMX) (也以PVA一14000作唯一碳源)研究了聚乙烯醇(PVA)分子量及有规立构性对PVA降解的影响。粪产碱菌KK314在含有O.1%PVA一1400Q的矿物溶液里快速生长;3天后除去90%以上的总有机碳。采用PVA—IMX时,降解缓慢,但2周后聚合物组分消失。不同分子量PVA(八聚体以上)间的生物降解能力没…     

聚乙烯醇降解细菌筛选及其降解特性

从聚乙烯醇泡棉的堆肥降解过程中筛选出可以有效降解聚乙烯醇的菌株,并研究其对聚乙烯醇的降解效果和降解特性。将聚乙烯醇泡棉经过3年的堆肥降解,利用傅里叶转换红外光谱(Fourier transform infrared spectroscopy,FTIR)检测泡棉的分子结构变化;采用Finley法从降解后的聚乙烯醇泡棉中筛选降解效果较好的菌株,通过菌落形态和细胞染色以及16S rRNA基因序列比对进行鉴定;通过紫外分光光度计检测菌株在降解聚乙烯醇材料过程中的菌体浓度变化和聚乙烯醇降解程度,并将筛选菌株对两种醇解度的聚乙烯醇降解效果进行对比。结果表明,经过3年的堆肥降解,聚乙烯醇泡棉分子结构中出现了新的羧基和羟基;筛选得到了四株菌,即Bacillus sp.DG01、Bacillus sp.DG02、Paenibacillus sp.DG03、Paenibacillus sp.DG04。这4株筛选菌株对3.0g/L PVA1788的降解率分别为67.27%、74.99%、56.74%和59.70%,对3.0 g/L PVA1799的降解率分别为58.27%、54.47%、43.32%和46.59%。PVA泡棉在堆肥降解过程中发生了明显的基团变化,4株菌的生长与聚乙烯醇的降解过程呈耦联关系,且4株菌株整体上对较低醇解度的PVA降解效果更好。     

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。     

聚乙烯醇降解酶研究进展

聚乙烯醇是一种广泛应用的水溶性聚合物,尤其作为纺织浆料。由于其生物难降解性,对水体会造成较大的污染,因此得到较多的关注。对聚乙烯醇生物处理的研究主要集中在生物降解酶和生物降解机理上,特别是随着对环境友好的酶加工纤维技术的不断发展,利用聚乙烯醇降解酶进行纺织脱浆已引起较大的兴趣。已发现的聚乙烯醇降解酶主要包括:聚乙烯醇氧化酶(仲醇氧化酶)、聚乙烯醇脱氢酶、β双酮水解酶(氧化型聚乙烯醇水解酶)。聚乙烯醇降解酶催化聚乙烯醇的生物降解主要分为两步进行。聚乙烯醇酶脱浆技术不仅节省了脱浆能耗,而且提高了脱浆废水的生物可降解性。     

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...     

聚乳酸的生物降解

聚乳酸(polylactic acid, PLA)因其良好的理化性能、生物相容性和生物降解性而备受关注，已被认为是石油基塑料最具潜力的替代者，但在实际应用中仍然存在降解缓慢循环周期长的问题，因此对PLA的生物降解深入研究对于解决塑料垃圾污染和缓解能源危机至关重要。近年来，有关微生物(放线菌、细菌和真菌)和酶(蛋白酶、脂肪酶、酯酶和角质酶)降解PLA的研究已经取得了一定的进展。本文从降解微生物、降解酶和降解机制等方面综述了PLA生物降解的研究进展，并展望了PLA生物降解研究未来的发展趋势。     

Biodegradation of photo-degraded mulching films based on polyethylenes and stearates of calcium and iron as pro-oxidant additives

Polyethylene film materials persist in the environment for a long time. Several bacterial species have been isolated from films buried in soil located in Murcia, Spain. Bacterial strains were characterized with a combination of culture-dependent methods and sequencing of part of the 16S ribosomal RNA gene (rDNA) after amplification by polymerase chain reaction (PCR). Three bacterial species common in soil were found attached to the polymer and identified as Bacillus. cereus, B. megaterium, and B. subtilis. These microorganisms, as well as Brevibacillus borstelensis, were tested for biodegradation susceptibility at 30 and 45 °C on highly photo-degraded polyethylene films (500 h under irradiation of Xe-Lamp-solar filter) that contained calcium and iron stearates as pro-oxidant additives. Biofilm formation developed on the photo-degraded materials after one week of bacterial treatment. Biodegradation of the polyethylene films was studied by chemiluminescence, ATR-FTIR, and GC-product analysis and the data confirm a more efficient biodegradation on the bioassays carried out at higher temperature. The CL emissions due to decomposition of oxidation species take place at lower temperatures; the decrease of carbonyl index and the disappearance of photogenerated low-molecular products with biodegradation were more efficient on the biodegraded films at 45 °C. Also, mineralization was evaluated by carbon dioxide measurements using an indirect impedance technique. Biodegradation by B. borstelensis and MIX at 30 °C was slow and in the range of 0.7-1.2% of mineralization after 90 days of bacterial bioassay. At 45 °C biodegradation was more efficient and in particular in the more photo-degraded films containing Ca and Fe stearates where mineralization extents reached values of 11.5% with B. borstelensis and 7-10% with the mixture of Bacillus (MIX).     

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     

Microbial transformation of chlorinated benzoates

Chlorinated benzoates enter the environment through their use as herbicides or as metabolites of other halogenated compounds. Ample evidence is available indicating biodegradation of chlorinated benzoates to CO₂ and chloride in the environment under aerobic as well as anaerobic conditions. Under aerobic conditions, lower chlorinated benzoates can serve as sole electron and carbon sources supporting growth of a large list of taxonomically diverse bacterial strains. These bacteria utilize a variety of pathways ranging from those involving an initial degradative attack by dioxygenases to those initiated by hydrolytic dehalogenases. In addition to monochlorinated benzoates, several bacterial strains have been isolated that can grow on dichloro-, and trichloro- isomers of chlorobenzoates. Some aerobic bacteria are capable of cometabolizing chlorinated benzoates with simple primary substrates such as benzoate. Under anaerobic conditions, chlorinated benzoates are subject to reductive dechlorination when suitable electron-donating substrates are available. Several halorespiring bacteria are known which can use chlorobenzoates as electron acceptors to support growth. For example, Desulfomonile tiedjei catalyzes the reductive dechlorination of 3-chlorobenzoate to benzoate. The benzoate skeleton is mineralized by other microorganisms in the anaerobic environment. Various dichloro- and trichlorobenzoates are also known to be dechlorinated in anaerobic sediments.     

Investigation into Stability of Poly(Vinyl Alcohol)-Based Opadry® II Films

Poly(vinyl alcohol) (PVA)-based formulations are used for pharmaceutical tablet coating with numerous advantages. Our objective is to study the stability of PVA-based coating films in the presence of acidic additives, alkaline additives, and various common impurities typically found in tablet formulations. Opadry® II 85F was used as the model PVA-based coating formulation. The additives and impurities were incorporated into the polymer suspension prior to film casting. Control and test films were analyzed before and after exposure to 40°C/75% relative humidity. Tests included film disintegration, size-exclusion chromatography, thermal analysis, and microscopy. Under stressed conditions, acidic additives (hydrochloric acid (HCl) and ammonium bisulfate (NH₄HSO₄)) negatively impacted Opadry® II 85F film disintegration while NaOH, formaldehyde, and peroxide did not. Absence of PVA species from the disintegration media corresponded to an increase in crystallinity of PVA for reacted films containing HCl. Films with NH₄HSO₄ exhibited slower rate of reactivity and less elevation in melting temperature with no clear change in melting enthalpy. Acidic additives posed greater risk of compromise in disintegration of PVA-based coatings than alkaline or common impurities. The mechanism of acid-induced reactivity due to the presence of acidic salts (HCl vs. NH₄HSO₄) may be different.     

Biomaterials of PVA and PVP in medical and pharmaceutical applications: Perspectives and challenges

Poly(vinyl alcohol) (PVA) has attracted considerable research interest and is recognized among the largest volume of synthetic polymers that have been produced worldwide for almost one century. This is due to its exceptional properties which dictated its extensive use in a wide variety of applications, especially in medical and pharmaceutical fields. However, studies revealed that PVA-based biomaterials present some limitations that can restrict their use or performances. To overcome these limitations, various methods have been reported, among which blending with poly(vinylpyrrolidone) (PVP) showed promising results. Thus, our aim was to offer a systematic overview on the current state concerning the preparation, properties and various applications of biomaterials based on synergistic effect of mixtures between PVA and PVP. Future trends towards where the biomaterials research is headed were discussed, showing the promising opportunities that PVA and PVP can offer.     

丛毛睾丸酮单胞菌ZD4-1和铜绿假单胞菌ZD4-3降解芳香烃化合物的机理

从某农药厂二沉池污泥中筛选分离得到两株革兰氏阴性的芳香烃降解菌ZD41和ZD43。经鉴定,它们分别属于Comamonas testosteroni和Pseudomonas aeruginosa。基于16S rDNA 序列的系统分类分析,结果表明,在分类地位上菌株ZD41和ZD43 分别属于两个不同的分类亚组。苯酚降解产物紫外光谱扫描和双加氧酶检测证明,菌株ZD41利用邻裂途径降解苯酚,而ZD43则通过间裂途径降解苯酚,邻裂途径的1,2双加氧酶和间裂途径的2,3双加氧酶都是可诱导的双加氧酶,其活性强烈的依赖于降解底物的出现。芳香烃降解试验结果表明,邻裂和间裂两种途径的降解性能不一样,虽然ZD43降解苯酚的效率要高于菌株ZD41,但是ZD41降解苯酚的pH值范围以及芳烃利用基质谱宽于后者。     

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.     

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.     

Preparation, characterization, and properties of chitosan-g-poly(vinyl alcohol) copolymer

The graft copolymer chitosan-g-poly(vinyl alcohol), with nontoxicity, biodegradability, and biocompatibility, was prepared by a novel method. The copolymer with porous net structure was observed by scanning electron microscopy (SEM). It is a potential method to combine chitosan with the synthetic polymers. The grafting reactions were conducted with various poly(vinyl alcohol) (PVA)/6-O-succinate-N-phthaloyl-chitosan (PHCSSA) feed ratios to obtain chitosan-g-poly(vinyl alcohol) copolymers with various PVA contents. The chemical structure of the chitosan-g-poly(vinyl alcohol) was characterized by Fourier transform infrared and nuclear magnetic resonance (NMR) spectroscopy. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), and SEM were also detected to characterize the copolymer.