Investigation on Microorganisms and their Degradation Efficiency in Paper and Pulp Mill Effluent

Paper and pulp mill is a source of major pollution generating industry leaving huge amount of intensely colored effluent to the receiving end. Rapid increase of population and the increased demand for industrial establishments to meet human needs have created problems such as over exploitation of available resources, increased pollution taking place on land, air and water environment. The intention of this research paper is to identify predominant bacteria and fungi in paper and pulp mill effluent in addition to evaluate the degradation efficiency of individual isolates and combination of isolates. Treatment efficiency of individual isolates and combination of isolates are evaluated by shake flask method. Combination of Pseudomonas Alkaligenes, Bacillus subtilis along with Trichoderma reesei shows higher BOD, COD reduction of 99% and 85% respectively. As individual isolates Pseudomonas Alkaligenes show 92% BOD reduction and 77% COD reduction over other bacterial isolates and Trichoderma reesei removed 99% BOD and 80% COD respectively.

Impact of microorganism degradation on hydrocarbon generation of source rocks:A case study of the Bozhong Sag,Bohai Bay Basin

The discovery of the Bozhong 19-6 gas field,the largest integrated condensate gas field in the eastern China in 2018,opened up a new field for the natural gas exploration deep strata in the Bohai Bay Basin,demonstrating there is a great potential for natural gas exploration in oil-type basins.The ethane isotope of the Bozhong 19-6 condensate gas is heavy,showing the characteristics of partial humic gas.In this paper,aimed at the source rocks of the Bozhong 19-6 gas field in the Bohai Bay Basin,the characteristics of the source rocks in the Bozhong 19-6 structural belt were clarified and the reason are explained from impact of microorganism degradation on hydrocarbon generation of source rocks why the condensate oil and gas had heavy carbon isotope and why it showed partial humic characteristics was explored based on the research of parent materials.The following conclusions were obtained:The paleontology of the Bozhong 19-6 structural belt and its surrounding sub-sags is dominated by higher plants,such as angiosperm and gymnosperm.During the formation of source rocks,under the intensive transformation of microorganism,the original sedimentary organic matter such as higher plants was degraded and transformed by defunctionalization.Especially,the transformation of anaerobic microorganisms on source rocks causes the degradation and defunctionalization of a large number of humic products such as higher plants and the increase of hydrogen content.The degradation and transformation of microorganism don't transform the terrestrial humic organic matter into newly formed“sapropel”hydrocarbons,the source rocks are mixed partial humic source rocks.As a result,hydrogen content incrased and the quality of source rocks was improved,forming the partial humic source rocks dominated by humic amorphous bodies.The partial humic source rocks are the main source rocks in the Bozhong 19-6 gas field,and it is also the internal reason why the isotope of natural gas is heavy.

Study on nitrile-degrading microorganisms

Two strains of bacteria were isolated from nitrile polluted soils, and identified as Corynebacterium boffmanii and Arthrobacter flavescens. Acetonitrile, propionitrile, butyronitrile and acrylonitrile were degraded by these bacteria to yield corresponding amides, carboxylic acids and ammonia. The nitrile-degrading abilities of these strains were investigated. The removal rates for the nitrile were nearly 100%, after these bacteria were grown in medium containing 10000 ppm of aceto-, propio-, or butyronitrile at 28 ℃ for 24h. When the reaction mkture consisting of 5000 ppm of above mentioned nitriles or acrylonitrile and 20g (dry cell) /L resting cells of the two strains in 0.06mol/L phosphate buffer (pH7.5) was incubated separately at 25 ℃ with moderate shaking for 15 or 45 min, the nitrile could be degraded completely. The optimum growth conditions for C.hoffmanii and A.flavescens were studied as well.

Widespread and active piezotolerant microorganisms mediate phenolic compound degradation under high hydrostatic pressure in hadal trenches

Phenolic compounds,as well as other aromatic compounds,have been reported to be abundant in hadal trenches.Although high-throughput sequencing studies have hinted at the potential of hadal microbes to degrade these compounds,direct microbiological,genetic and biochemical evidence under in situ pressures remain absent.Here,a microbial consortium and a pure culture of Pseudomonas,newly isolated from Mariana Trench sediments,efficiently degraded phenol under pressures up to 70 and 60 MPa,respectively,with concomitant increase in biomass.By analyzing a high-pressure(70 MPa)culture metatranscriptome,not only was the entire range of metabolic processes under high pressure generated,but also genes encod-ing complete phenol degradation via ortho-and meta-cleavage pathways were revealed.The isolate of Pseudomonas also contained genes encoding the complete degradation pathway.Six transcribed genes(dmpKLMNOP_(sed))were functionally identified to encode a multicomponent hydroxylase catalyzing the hydroxylation of phenol and its methylated derivatives by heterogeneous expression.In addition,key catabolic genes identified in the metatranscriptome of the high-pressure cultures and genomes of bacterial isolates were found to be all widely distributed in 22 published hadal microbial metagenomes.At microbiological,genetic,bioinformatics,and biochemical levels,this study found that microorganisms widely found in hadal trenches were able to effectively drive phenolic compound degradation under high hydrostatic pressures.This information will bridge a knowledge gap concerning the microbial aromatics degradation within hadal trenches.

Degradation of pyrene by immobilized microorganisms in saline-alkaline soil

Biodegradation of polycyclic aromatic hydrocarbons （PAHs） is very difficult in saline-alkaline soil due to the inhibition of microbial growth under saline-alkaline stress. The microorganisms that can most effectively degrade PAHs were screened by introducing microorganisms immobilized on farm byproducts and assessing the validity of the immobilizing technique for PAHs degradation in pyrene-contaminated saline-alkaline soil. Among the microorganisms examined, it was found that Mycobacterium sp. B2 is the best, and can degrade 82.2% and 83.2% of pyrene for free and immobilized cells after 30 days of incubation. The immobilization technique could increase the degradation of pyrene significantly, especially for fungi. The degradation of pyrene by the immobilized microorganisms Mucor sp. F2, fungal consortium MF and co-cultures of MB＋MF was increased by 161.7% （P 〈 0.05）, 60.1% （P 〈 0.05） and 59.6% （P 〈 0.05） after 30 days, respectively, when compared with free F2, MF and MB＋ME Scanning electron micrographs of the immobilized microstructure proved the positive effects of the immobilized microbial technique on pyrene remediation in saline- alkaline soil, as the interspace of the carder material structure was relatively large, providing enough space for cell growth. Co-cultures of different bacterial and fungal species showed different abilities to degrade PAHs. The present study suggests that Mycobacterium sp. B2 can be employed for in situ bioremediation of PAHs in saline-alkaline soil, and immobilization of fungi on farm byproducts and nutrients as carriers will enhance fungus PAil-degradation ability in saline-alkaline soil.

Biodegradation of Crystalline Chitin:A Review of Recent Advancement,Challenges,and Future Study Directions

Chitin is the second most abundant renewable polysaccharide on Earth.The degradation of chitin into soluble and bioactive N-acetyl chitooligosaccharides(NCOSs)and N-acetyl-D-glucosamine(GlcNAc)has emerged as a pivotal step in the efficient and sustainable utilization of chitin resources.However,because of its dense structure,high crystallinity,and poor solubility,chitin typically needs pretreatment via chemical,physical,and other methods before enzymatic conversion to enhance the accessibility between substrates and enzyme molecules.Consequently,there has been considerable interest in exploring the direct biological degradation of crystalline chitin as a cost-effective and environment-friendly technology.This review endeavors to present several biological methods for the direct degradation of chitin.We primarily focused on the importance of chitinase containing chitin-binding domain(CBD).Additionally,various modification strategies for increasing the degradation efficiency of crystalline chitin were introduced.Subsequently,the review systematically elucidated critical components of multi-enzyme catalytic systems,highlighting their potential for chitin degradation.Furthermore,the application of microorganisms in the degradation of crystalline chitin was also discussed.The insights in this review contribute to the explorations and investigations of enzymatic and microbial approaches for the direct degradation of crystalline chitin,thereby fostering advancements in biomass conversion.

Biodegradation Characteristics of Environmental Endocrine Disruptor Di-n-butyl Phthalate

Objective The biodegradation characteristics of di-n-butyl phthalate (DBP), an environmental endocrine disruptor, were studied by the method of dominant bacteria and immobilized microorganisms. Methods Taking DBP as the only carbon source to acclimatize the collected activated sludge, the concentration of DBP increased progressively in the process of acclimatization. Plate streaking was used to separate 1 strain of the degradation dominant bacteria after acclimatization. Better conditions to degrade DBP by the bacterium could be obtained through orthogonal experiments and the bacterium was identified. Then the acclimated activated sludge was made to immobilize the microorganism using polyvinyl alcohol as entrapment agent. The immobilized microorganism degraded DBP at different conditions. Results The appropriate conditions to degrade DBP by the dominant bacteria were: degradation time, 32 h; DBP concentration, 200 mg/L; rate of shaking incubator, 100 r/min; pH, 7 and temperature, 30℃. DBP could be degraded by more than 95% under such conditions. The bacteria were identified as pseudomonas. The proliferated immobilized microorganisms degraded DBP more effectively and more adapted to temperature and pH than the free acclimated activated sludge. Conclusion One strain of DBP degradation dominant bacteria was separated from the acclimatized activated sludge. It could grow with DBP as the only carbon source and energy, and degraded DBP effectively. After having been immobilized and proliferated, the dominant bacteria could keep a higher biological activity and degrade DBP more effectively than activated sludge.

Preliminary Studies on Chlorimuron Degradation in Soil by Effective Microogranisms

A wheat （Triticum aestivurn L.） bioassay method was used for preliminary determination of chlorimuron degradation in soil by EM （effective microorganisms）. Under the conditions of this study, chlorimuron half-life was greater than 30-50 days in soil containing different initial concentrations of chlorimuron. After adding EM, chlorimuron degradation half-life ranged from 10-15 days, which was about 15-30 days shorter than without EM. Chlorimuron degradation was not significantly affected by EM populations applied at 50-200 mL·kg^-1. Both monopotassium phosphate and urea enhanced the ability of EM to degrade chlorimuron, but brown sugar had no significant effect.

Degradation Performance and Biodiversity of an Anaerobic Polyvinyl Alcohol-Degrading Microbial Community

Polyvinyl alcohol( PVA) is a water-soluble synthetic polymer that is hard to biodegrade. PVA-degrading microorganisms were previously reported as unitary bacteria and most of them have been identified as aerobes. In this work,a microbial community was cultured anaerobically and its degradation performance and biodiversity were analyzed. The microbial community was cultured for more than 40 d,which represents a highly efficient degradation performance with a chemical oxygen demand removal efficiency of 88. 48%. Operational taxonomic unit-based analysis of the sequences revealed a highly diverse community in the reactor. To note,metagenome 16s rDNA sequencing delineated 19 phyla and 41 classes. Specifically, proteobacteria, chlamydiae, bacteroidetes,firmicutes,and planctomycetes play key roles in the biodegradation processes. Moreover,the betaproteobacteria class belonging to the proteobacteria phylum was the predominant bacterial members in this community. Our results demonstrated that anaerobic treatment of PVA wastewater is feasible and confers degradation by a highly diverse microbial community.

Advances in Biodegradation of Aflatoxins

Aflatoxins are secondary metabolites of fungi such as Aspergillus flavus and Aspergillus parasiticus. They are one of the contaminants most common in food and feed, with high toxicity and carcinogenicity. Aflatoxins usually enter animal body together with feed and then enter human body by food chain, thereby seriously threatening human health. In recent years, the degradation of aflatoxins has become a hot research topic. This study overviewed the characteristics and detoxification ways of aflatoxins, specifically for the advances in biodegradation and degradation products of aflatoxins.

A Unified Model for the Degradation Kinetics of Pesticides Applied Continually to Soils

This paper deduces a kinetic model for microbial degradation of pesticides in soils:where x is the concentration of pesticide at time t, so the initial concentration of the pesticide, me the initial number of pesticide-degrading microorganisms, M the carrying capacity for the microorganisms, μ the specific growth rate of the microorganisms, and k the rate constant for the pesticide degradation.In periodic applications of pesticides, this model can be used to continuously describe every degradation curve. Whether a lag phase occurs or not, we can obtain the minimum residue of the pesticide (xe):xe=xdexp(-kMr)/[1-exp(-ker) ]where r is the regular time internals between applications, and xd the dosage of the pesticide.

Microorganisms Associated with Vegetable Oil Polluted Soil

Vegetable oil Spills are becoming frequent and are potentially more challenging than petroleum hydrocarbon spills. Microbial lipases occupy a place of prominence among biocatalysts are often used for remediation of vegetable oil-polluted sites. This work was carried out to isolate microorganisms from oil-polluted sites and screen them for their lipolytic activity. Microorganisms were isolated from eight experimental soil samples contaminated with different types of vegetable oil, soil from an oil mill in Ibadan, and normal uncontaminated soil as a control. The isolates were characterized, identified and those common to at least one of the experimental sites and oil mill sites were screened for their lipolytic activity. Data obtained were analysed using Duncan Multiple Range Test. Seventy three microorganisms were isolated from the polluted soil and identified as species of Bacillus (16), Pseudomonas (12), Flavobacterium (6), Alcaligenes (2), Proteus (3), Micrococcus (1), Aspergillus (9), Penicillium (6), Saccharomyces (4), Geotrichum (1), Kluveromyces (1). Bacillus subtilis, Bacillus licheniformic, Pseudomonas cepacia, Pseudomonas fluorescens, Flavobacterium sp., Alcaligenes sp. and Candida parapsilosis which were common to at least one of the experimental site and oil mill site were preliminarily screened for lipolytic activity and all nine confirmed by presence of halos around the colonies. These screened organisms have potential for the degradation of fatty waste. They could therefore be employed in environmental clean-up of vegetable oil spill site.

高效烃降解菌群的驯化、降解特性及初步应用

微生物技术在石油污染土壤的修复中具有广阔的应用前景,而获得具有高降解效率的菌(菌群)是保证高效修复的关键。该研究从4种不同含油土壤中驯化、培养获得稳定、高效降解石油烃的1号菌群,对其进行高通量测序,确定菌群组成;研究不同环境因素对该菌群石油烃降解能力的影响,确定了最佳降解条件;对菌群降解石油烃的特性和降解动力学进行了分析;探究了该菌群在较高浓度含油土壤中的应用潜力,以及以破碎荞麦壳为载体,将菌群固定化后修复石油烃-镉复合污染土壤的能力。结果表明,该菌群主要由寡养单胞菌属(Stenotrophomonas)、假单胞菌属(Pseudomonas)、苍白杆菌属(Ochrobactrum)、乳杆菌属(Lactobacillus)和无色杆菌属(Achromobacter)等组成;在原油质量浓度为0.5%,p H为8,盐度为1%,温度为35℃,C∶N∶P为100∶2∶1,以硝酸铵为氮源的最佳条件下,培养10 d后,菌群对石油的降解率由52.1%提高至76.6%;GC-MS分析结果显示,培养9 d和24 d后菌群对C13~C26烷烃平均降解率分别为90.3%和97%,说明该菌群能够快速高效降解中长链烷烃。菌群对原油初始浓度为0.5%和4%的降解符合一级反应动力学模型。将菌群接种于石油含量为4 631 mg/kg、8 591 mg/kg的土壤中,40 d后降解率分别为47.7%、26.4%;固定化后的菌群用于修复石油烃-镉复合污染土壤,石油烃降解率、土壤脱氢酶活性和过氧化氢酶活性高于其他组,可交换态镉的浓度低于其他组。以上结果充分显示了该菌群在石油浓度较高的土壤以及石油烃-镉复合污染土壤修复中的应用潜力。

昆虫及肠道微生物降解塑料的研究现状及机制分析

综述昆虫及肠道微生物降解塑料的研究现状及作用机制。根据目前的研究现状,考虑降解过程中多因素的影响,提出降解塑料的两种思路:思路一从现有能够降解塑料的昆虫中筛选降解率高的昆虫,从昆虫肠道分离可降解塑料的菌株,富集菌株,制作菌球,配合紫外线、pH、温度、机械粉碎、降解的基质等多因素和能够改变塑料疏水性的物质,提高塑料降解率;思路二利用NGS(Next Generation Sequencing,NGS)、气相色谱-质谱联用技术、凝胶渗透色谱仪等技术,结合蛋白质组学、代谢组学、转录组学等组学,研究昆虫及肠道微生物降解塑料的关键节点和蛋白质,降解时酶的触发机制,昆虫摄食塑料时内分泌调控机制,异源异属的微生物共协降解机制,为昆虫及肠道微生物降解塑料提供研究思路。

基因工程菌在石油污染修复中的研究进展与前景

构建基因工程菌(genetically engineered microorganisms,GEMs)是石油污染生物修复的重要发展方向.目前,通过基因编辑、过表达和定向进化等手段改造微生物的石油污染物降解和调控途径,可以提高微生物的环境适应能力和污染物降解能力,用于石油污染物的生物降解和监测.本文概述了石油污染物降解基因工程菌的主要构建策略,包括选择和改造宿主菌、改造与优化石油污染物关键酶和代谢通路、开发微生物全细胞传感器和构建基因工程菌的自毁程序.此外,基因工程菌也可用于石油污染的酶修复、微生物菌群修复和细菌-植物联合修复.随着系统生物学和合成生物学在降解微生物中的应用,基因工程菌在石油污染修复中展现出良好的研究和应用前景.

草地生态系统保护、修复与功能提升的关键科学问题

草地占我国国土面积的27.6%,在保障我国生态安全中发挥着重要作用。本文梳理了我国从单一追求草地资源的物质生产功能,到生产和生态兼顾,再到目前的生态优先、多功能目标管理的发展历程,分析了草地保护与修复政策施力点及其在遏制草地退化中的作用,分析了我国草地修复过程中的乡土草种质资源、土壤养分和土壤微生物等制约因素,介绍了依靠自然过程,将退化草地恢复到生物多样性、稳定性与地带性群落接近的草地近自然恢复理念与途径;凝练了我国草地保护和修复亟需解决的关键科学问题。建议在新时代草地保护与修复政策的保障下,尊重自然、顺应自然、践行近自然恢复理念,引领新时代由植被到生态系统的草地保护与修复工作。

喀斯特石漠化区林草间作对土壤养分及微生物数量的影响

林草间作具有水源涵养、提高土壤肥力和增加生物多样性等多重优势,是喀斯特石漠化区生态恢复较为理想的模式之一。为了探讨林草间作对喀斯特石漠化区土壤养分和微生物数量的影响,在贵州省关岭县板贵乡选择花椒(Zanthoxylum bungeanum)+拉巴豆(Dolichos lablab)间作、花椒+雀稗(Paspalum thunbergii)间作及单作花椒3种模式开展研究。结果表明:与花椒单作相比,土壤中有机质、全氮、速效钾、碱解氮含量均有所增加,土壤pH降低,土壤微生物数量增加,其中真菌数量显著增加(P<0.05)。0-10 cm土壤中有效磷含量显著降低(P<0.05),而10-20 cm土壤中有效磷增加。相关性分析表明,0-10 cm土壤中细菌数量与有效磷含量显著负相关(P<0.05),真菌数量与有机质含量极显著正相关(P<0.05),与全氮、有效磷含量显著正相关(P<0.05),与pH显著负相关(P<0.05);10-20 cm土壤中细菌数量与速效钾含量显著正相关(P<0.05),真菌数量与pH显著负相关(P<0.05)。说明在喀斯特石漠化地区花椒和牧草构成的林草间作生态恢复模式在提高土壤养分、增加微生物数量方面有积极作用。

木质纤维素的微生物法降解及其饲料化研究进展

农作物秸秆是农业生产过程中的副产物,是地球上第一大可再生资源,我国是农作物秸秆资源量较为丰富的国家。木质纤维素是秸秆细胞壁的主要成分,是一种可循环利用的物质资源,在饲料领域具有很大的利用价值。木质纤维素的结构紧密且复杂,利用难度大,采用生物法降解木质纤维素是一种绿色、安全、高效的方式。文章概述了木质纤维素的组成成分及结构,重点叙述了自然界中降解木质纤维素的微生物种类,及微生物降解木质纤维素各组分的降解机理,以期为研究生物降解木质纤维素提供参考依据,进而促进秸秆饲料化的发展进程。

降解菌Pseudomonas sp. AT2对莠去津胁迫下水稻生长的影响机制

农田土壤中残留的莠去津易对后茬敏感作物造成药害,利用功能微生物调控作物中残留莠去津降解是缓解其药害的有效方式。本研究分析了水稻根际微生物群落及土壤中莠去津降解基因对莠去津胁迫的响应,并从水稻根际土壤中分离出一株莠去津降解菌Pseudomonas sp.AT2,通过盆栽试验探究了莠去津胁迫下菌株AT2对水稻生长及莠去津降解的影响机制。结果表明:莠去津胁迫可显著改变水稻根际细菌的群落结构,并提高根际土壤中莠去津降解基因TrzN、AtzB和AtzC的丰度。莠去津胁迫下,接种降解菌AT2组水稻的株高、根长、干重和叶绿素含量均显著增加,MDA的积累减少,说明AT2可缓解水稻的氧化胁迫损伤;接种降解菌AT2处理组土壤和水稻中莠去津含量分别比对照降低了14.9%和47.1%~57.5%,说明AT2促进了土壤及水稻中莠去津的降解。另外,莠去津胁迫下,接种AT2还可诱导水稻中莠去津降解基因的上调表达,表达量为未接菌对照组的1.3~2.7倍。研究表明,根际接种降解菌株能激活水稻体内降解基因的表达,促进“土壤-水稻”体系中莠去津的降解,缓解环境中残留莠去津对水稻的毒害作用。

秸秆堆肥功能微生物与高效降解菌剂的研究进展

秸秆通过堆肥发酵生产有机肥是秸秆资源高效利用的有效途径。在堆肥中添加高效微生物降解菌剂能加速秸秆腐熟的过程,使复杂的有机物在短时间内降解为植物可利用的简单化合物。国内外关于产木质纤维素降解酶微生物的研究较多,但关于秸秆降解菌的应用研究较少。该文详细介绍了秸秆降解的功能微生物、高效降解菌剂及其应用效果,阐述了多种功能微生物在降解秸秆间的协同作用,并对多功能秸秆降解菌剂的研究现状和存在问题进行分析,为今后开发高效多效秸秆降解菌剂提供了理论基础。