Effects of Tween 80 and rhamnolipid on the extracellular enzymes of Penicillium simplicissimum isolated from compost

Extracellular enzymes of microorganisms play an important role in the decomposition of macromolecules in the composting process. In this study, the effects of Tween 80 and rhamnolipid on the extracellular amylase, carboxymethyl cellulose enzyme (CMCase), xylanase and protease of Penicillium simplicissimum isolated from compost were investigated during solid-state fermentation. The results showed that the enzyme activities of amylase, CMCase and xylanase were increased by Tween 80 and rhamnolipid, which, however, had a negative effect on the protease production. The stimulative effects on the three enzymes were quite different during the whole fermentation process. Tween 80 and rhamnolipid also increased the fungal biomass slightly. As a result of the enhanced enzyme activities, the organic matter were also improved to different extents by both surfactants, and the decomposition rates of hemicellulose and cellulose were increased about 8.0% and 11.6% by Tween 80 at best, respectively, as well as 5% and 5.5% by rhamnolipid.     

Dynamics of water-soluble carbon substances and microbial populations during the composting of de-inking paper sludge

Composting is an alternative method to dispose of de-inking paper sludge (DPS). Today, few studies have investigated the water-soluble carbon (WSC) substances as indicators of the decomposition process and the microbial changes taking place during the composting of DPS. Accordingly, the goal is to study their dynamics during the composting of DPS at three nitrogen levels, 0.6%, 0.7% or 0.9% total N, using mechanical turning. The changes in WSC substances, microbial biomass carbon (MBC) and, total and DPS microbial populations were monitored during 24 weeks. Also, microorganisms were identified and tested for the production of selected enzymes. Regardless of N treatments, the dynamic of WSC substances indicated that cellulose and hemicellulose fractions of DPS fibers were mainly biodegraded during the first 8 weeks while the more resistant carbon (C) fractions were biodegraded thereafter. MBC also evolved regardless of N treatments but was correlated to WSC substances. Its high values decline mostly after 12 weeks indicating the exhaustion of this source of C energy for microbial growth and the stabilisation of DPS organic matter. The dynamic and identified microorganisms were comparable to those observed in other composting processes. However, the results pointed out that those mostly implicated in the hydrolysis of DPS fibers were the thermophilic actinomycetes and fungi and, by comparison to the 0.6% or 0.7% N treatment, they decreased in presence of the 0.9% N treatment. Most microorganisms were hemicellulolytic bacteria, while actinomycetes and fungi were capable of degrading a wide variety of substrates. Overall, dynamics of WSC substances and microbial populations indicated that during composting, DPS decomposition obey a two phase decay while, contrary to the lowest N treatment, the 0.9% N treatment has slowed down this process by harming the important microbial populations implicated in the degradation of DPS fibers.     

葡萄籽对猪粪秸秆高温堆肥中微生物群落与碳氮含量的影响

以猪粪与秸秆(鲜质量10.5∶1)为基础,在自制的强制通风静态堆肥反应箱中进行堆肥化试验,研究添加8%葡萄籽对猪粪秸秆高温堆肥中微生物群落演替和碳氮转化的影响.在堆肥化的30 d里,分7次采集不同时期的堆肥样品,测定堆肥中微生物区系、微生物生理群的数量及堆肥碳氮含量.结果表明：添加葡萄籽使堆肥中细菌数量略高、放线菌数量显著增加、真菌数量明显降低,细菌/放线菌下降;氨化细菌和反硝化细菌数量降低;而硝化细菌、固氮菌和纤维素分解菌数量增多;铵态氮和有机碳含量下降,而硝态氮含量明显提高.堆肥中硝态氮含量与放线菌数量呈极显著正相关关系.添加葡萄籽使堆体升温快且高温期稳定,堆肥含水率波动较小,从而使堆肥高温期放线菌和亚硝化细菌的波动较小,数量较高,有利于堆肥中硝态氮含量的增加.     

表面活性剂对绿色木霉产纤维素酶影响

利用绿色木霉,以稻草为唯一碳源,采用液态发酵的方法,分别加入生物表面活性剂鼠李糖脂和化学表面活性剂Tween 80,重点研究了生物表面活性剂对绿色木霉产纤维素酶的影响。实验分析了加入不同浓度的表面活性剂时滤纸酶活、羧甲基纤维素酶活、微晶纤维素酶活及酶液的表面张力随时间的变化情况。结果表明,添加鼠李糖脂能够促进绿色木霉产酶,分别使滤纸酶活、羧甲基纤维素酶活、微晶纤维素酶活最大提高了1.08倍,1.6倍和1.03倍。与Tween 80相比,鼠李糖脂促进产酶的效果明显优于Tween 80。     

Succession and activity of microorganisms in stored bagasse

Summary Fresh sugarcane bagasse was fermented under defined conditions and investigated regarding a microbial succession during fermentation, in view of the enzyme activities of microorganisms against the main bagasse components: sucrose, pectin, hemicellulose, cellulose, and lignin.Altogether, 400 pure cultures of microorganisms were obtained from 8 g bagasse during 6.5 days of storage. This flora consists of bacteria (74%), actinomycetes (6%), yeasts (13%), and fungi (7%). The yeasts dominate in early fermentation, followed by bacteria, and then by actinomycetes and fungi.This succession coincides with the enzymic activities of the isolated organisms during fermentation. At first, residual sugar is consumed predominantly by the yeasts. Then the bacteria degrade the pectin, the hemicellulose, and in parts, the cellulose. Later, the actinomycetes and the fungi imperfecti attack the hemicellulose, the cellulose, and, partly, the lignin within the bagasse fiber.These results are corroborated by investigations using bagasse from bulk storage.     

微生物发酵产木聚糖酶研究进展

木聚糖是植物半纤维素的主要成分,是自然界中仅次于纤维素的可再生资源。木聚糖酶是一类重要的木糖苷键水解酶酶系,可将木聚糖逐次降解为低聚木糖及木糖,在饲料、造纸、食品和生物转化等行业应用广泛。目前利用微生物发酵生产木聚糖酶的研究很多,菌种涉及到细菌、真菌等,其发酵生产木聚糖酶的工艺、产量及特性也各有不同,对此进行了综述,并展望了木聚糖酶发酵生产的研究方向。     

Selection and characteristics of a switchgrass-colonizing microbial community to produce extracellular cellulases and xylanases

A microbial community was selected for growth on dried and NaOH-treated switchgrass. During a 14-day liquid cultivation, a 70% loss in dry weight was observed during the first 4 days and after 14 days, the hemicellulose and cellulose in the system were degraded by 73.5% and 67.3%, respectively. The carboxymethyl cellulase (CMCase) and xylanase levels reached 0.21 and 3.75 IU, respectively. The optimal pH for CMCase and xylanase activities was 5 and 6, respectively. The optimal reaction temperature of CMCase and xylanase was 60°C. A library of bacterial and fungal ribosomal gene sequences obtained from the community showed the presence of Achromobacter xylosoxidans and Alcaligenes faecalis and of Fusarium sporotrichioides. To our knowledge, this was the first report on a microbial community selected in the presence of switchgrass to produce extracellular cellulases and xylanases.     

Fungi isolated from olive ecosystems and screening of their potential biotechnological use

This study investigated the fungi diversity of fresh olive (Olea europaea L.) fruits, olive paste (crushed olives) and olive pomace (solid waste) and screened and quantified enzymatic activities with biotechnological applications. Fungi were randomly isolated from olive cultivars from Castilla La Mancha region (Spain). Identification included comparison of their polymerase chain reaction (PCR) amplicons of the ITS1-5.8S-ITS2 ribosomal DNA region, followed by nucleotide sequence analysis. Fourteen different species with DNA sequences of different similarities were identified, belonging to seven different genera (Aspergillus, Penicillium, Rhizomucor, Mucor, Rhizopus, Lichtheimia and Galactomyces). Aspergillus fumigatus, followed by Galactomyces geotrichum, Penicillium commune and Rhizomucor variabilis var. regularior were the most frequent species. Specific enzyme screening was assayed on agar plates, using cellobiose, carboxymethylcellulose (CMC), polygalacturonic acid and CaCl(2)/Tween 80 as substrates for β-glucosidase, carboxymethylcellulase (CMCase), polygalacturonase and lipase, respectively. Species exhibiting the best activities were: Aspergillus fumigatus (for β-glucosidase, CMCase and lipase); Rhizopus oryzae (for β-glucosidase and lipase); Rhizomucor variabilis (for β-glucosidase, CMCase and polygalacturonase); Mucor fragilis (β-glucosidase, CMCase and lipase); Galactomyces geotrichum (for β-glucosidase, polygalacturonase and lipase) and Penicillium commune and Penicillium crustosum (for lipase). The species that had shown the best enzymatic activities were grown on hemicellulose, cellulose and pectin and some activities were quantified (xylanase, cellulase, β-glucosidase and pectinase). An isolate of A. fumigatus and one of A. niger showed the best cellulase and xylanase activities, while no species presented good pectinase and β-glucosidase activities. The selected species with potential enzymatic activities could be used for future applications of industrial interest.     

In vitro Studies on lignocellulose degradation by microbial strains isolated from composting processes

An in vitro study of different strains isolated from composting piles in relation to their capacity to biodegrade lignocellulose was achieved. Thirteen microorganisms (five bacteria, one actinomycete, and seven fungi) isolated from compost windrows were grown on agricultural wastes and analyzed for cellulose, hemicellulose, and lignin degradation. Hemicellulose fraction was degraded to a lesser extent because only two of the isolates, B122 and B541, identified as Bacillus licheniformis and Brevibacillus parabrevis, respectively, were able to decrease the concentration of this polymer. On the contrary, most of the isolates were capable of reducing cellulose and lignin concentrations; strain B541 was the most active cellulose degrader (51%), while isolate B122 showed higher lignin degradation activity (68%). Consequently, an increase in humification indices was detected, especially with respect to humification index (HI) for both bacteria and CAH/AF in the case of strain B122. According to these data, the use of microbial inoculants as a tool to improve organic matter biodegradation processes (i.e., composting) may become important if microorganisms’ capabilities are in accordance with the final characteristics required in the product (high humic content, lignin content decrease, cellulose concentration decrease, etc.).     

畜禽粪便堆肥过程中酶活性及微生物数量的变化研究

实验选取鸡粪和猪粪进行好氧堆肥发酵,研究畜禽粪便腐熟过程中酶活性和微生物的变化趋势以及相互联系。结果表明:过氧化氢酶活性和纤维素酶活性在堆肥初期较高,随后迅速降低,最终过氧化氢酶维持在9~12ml/g之间,纤维素酶维持在12.37~15.07mg/(kg·h)之间,而脲酶活性变化趋势为"升高-降低-升高"。细菌数量变化趋势为"低-高-低";放线菌为"高-低";真菌为"高-低-高"。通过相关分析发现,放线菌可能是影响堆肥中过氧化氢酶和纤维素酶的关键因素。鸡粪中放线菌与过氧化氢酶呈极显著正相关;猪粪中放线菌与过氧化氢酶和纤维素酶呈显著正相关;鸡粪+猪粪中放线菌与过氧化氢酶和纤维素酶呈极显著正相关。     

Metaproteomics reveals major microbial players and their biodegradation functions in a large-scale aerobic composting plant

Composting is an appropriate management alternative for municipal solid waste; however, our knowledge about the microbial regulation of this process is still scare. We employed metaproteomics to elucidate the main biodegradation pathways in municipal solid waste composting system across the main phases in a large-scale composting plant. The investigation of microbial succession revealed that Bacillales, Actinobacteria and Saccharomyces increased significantly with respect to abundance in composting process. The key microbiologic population for cellulose degradation in different composting stages was different. Fungi were found to be the main producers of cellulase in earlier phase. However, the cellulolytic fungal communities were gradually replaced by a purely bacterial one in active phase, which did not support the concept that the thermophilic fungi are active through the thermophilic phase. The effective decomposition of cellulose required the synergy between bacteria and fungi in the curing phase.     

Variation in microbial population during composting of agro-industrial waste

Two compost piles were prepared, using two ventilation systems: forced ventilation and ventilation through mechanical turning. The material to compost was a mixture of orange waste, olive pomace, and grass clippings (2:1:1 v/v). During the composting period (375 days), samples were periodically taken from both piles, and the enumeration of fungi, actinomycetes, and heterotrophic bacteria was carried out. All studied microorganisms were incubated at 25 and 55 °C after inoculation in appropriate growth media. Fungi were dominant in the early stages of both composting processes; heterotrophic bacteria proliferated mainly during the thermophilic stage, and actinomycetes were more abundant in the final stage of the composting process. Our results showed that the physical and chemical parameters: temperature, pH, moisture, and aeration influenced the variation of the microbial population along the composting process. This study demonstrated that composting of these types of wastes, despite the prolonged mesophilic stage, provided an expected microbial variation.     

Relative fibrolytic activities of anaerobic rumen fungi on untreated and sodium hydroxide treated barley straw in in vitro culture

The fibrolytic activities of rumen fungi were studied in terms of dry matter loss, plant cell wall degradation and enzyme (cellulase and xylanase) activities, when grown in vitro on either untreated or sodium hydroxide treated stems of barley straw over a 12 day period. Changes in fungal growth, development and overall biomass were followed using chitin assay and scanning electron microscopy. Treatment with sodium hydroxide resulted in a decrease in the NDF content together with the disruption of cuticle and the loosening and separation of the plant cells within the straw fragments. The enzyme activities of the anaerobic fungi have a high positive correlation (R(2)=0.99) with their biomass concentration assessed by chitin assay indicating that chitin is a valuable index for the estimation of the fungal biomass in vitro. The anaerobic fungi produced very extensive rhizoidal systems in these in vitro cultures. After incubation with rumen fungi, dry matter losses were, respectively, 35% and 38% for the untreated and treated straw samples and the overall fungal biomass, determined by chitin assay, was significantly higher in the treated samples. In vitro degradation of cellulose and hemicellulose was also higher in the treated than that of untreated cultures. Although, comparatively, xylanase activity was higher than that of cellulase, the cellulose fraction of the straw was degraded more than hemicellulose in both treated and untreated straw.     

Microbial community succession and lignocellulose degradation during agricultural waste composting

The changes of microbial community during agricultural waste composting were successfully studied by quinone profiles. Mesophilic bacteria indicated by MK-7 and mesophilic fungi containing Q-9 as major quinone were predominant and seemed to be important during the initial stage of composting. Actinobacteria indicated by a series of partially saturated and long-chain menaquinones were preponderant during the thermophilic period. While Actinobacteria, fungi and some bacteria, especially those microbes containing MK-7(H4) found in Gram-positive bacteria with a low G+C content or Actinobacteria were found cooperate during the latter maturating period. Since lignocellulsoe is abundant in the agricultural wastes and its degradation is essential for the operation of composting, it’s important to establish the correlation between the quinone profiles changes and lignocellulose degradation. The microbes containing Q-9 or Q-10(H2) as major quinone were found to be the most important hemicellulose and cellulose degrading microorganisms during composting. While the microorganisms containing Q-9(H2) as major quinone and many thermophilic Actinobacteria were believed to be responsible for lignin degradation during agricultural waste composting.     

Microbial decomposition of post-harvest sugarcane residue

A laboratory in situ composting study was conducted as a possible alternative method for the current practice of open air burning of post-harvest sugarcane residue by sugarcane farmers. In situ composting of the sugarcane residue by the indigenous bacteria and fungi was accelerated using molasses as an initial substrate. A one-time application of molasses boosted the soil microbial population. which started to decompose the ligno-cellulosic fractions of the residue. The study showed significant differences in several parameters among the control and molasses applied treatments, namely, visual decomposition of residue, bacterial and fungal population, soil pH, cellulose content, cellulase activity. and soil organic matter. Further study is needed to refine the process for the future application of this technology as a possible alternative to the current practice of open air burning of sugarcane residue by farmers.     

蘑菇培养料堆制过程中微生物的演替及作用

蘑菇培养料堆制的完成依赖于微生物群落共同作用来实现。综述了堆制阶段培养料中细菌、放线菌、真菌三大类型菌群出现、发展的规律 ,各自作用特点以及它们之间的相关性、拮抗性 ,同时从呼吸途径、酶学角度阐述了嗜热真菌对料选择性的形成和蘑菇菌丝生长的积极意义。     

Diversity of Bacteria and Fungi in Aerosols During Screening in a Green Waste Composting Plant

This article outlines a comprehensive analysis of the microbial diversity of aerosols produced during screening in a green waste composting plant using both culture and molecular techniques. Bacteria, thermophilic actinomycetes and fungi were quantified in the aerosols. The structure of the microbial community was examined using a fingerprint technique and DNA libraries. The results show: (i) the very high diversity of bacteria and fungi in aerosols produced during the composting screening stage, (ii) the low percentage of cultivability for bacteria in aerosols, (iii) the abundance of Thermoactinomyces spp. and Aspergillus spp. in compost aerosols.     

木聚糖酶基因研究进展

半纤维素分解微生物在自然界碳素循环中起着重要作用,半纤维素是植物多糖的重要成分之一。木聚糖则是半纤维素的主要成分。木聚糖酶(EC3.2.1.8)可催化木聚糖的水解,在各种各样的生物体里都发现有木聚糖酶,如细菌、放线菌、真菌。在过去几十年里,有超过100个木聚糖酶基因被克隆进同源或异源宿主中,其目的是为了超表达木聚糖酶和改变它们的特性以适应商业应用。木聚糖酶的应用极其广泛,可用于生物转化、造纸、食品、饲料、能源、纺织等行业。尤其是迫切的环境问题将进一步促进木聚糖酶研究的开展。     

Simultaneous production and induction of cellulolytic and xylanolytic enzymes in aStreptomyces sp.

Extracellular cellulolytic and xylanolytic enzymes ofStreptomyces sp. EC22 were produced during submerged fermentation. The cell-free culture supernatant of the streptomycete grown on microcrystalline cellulose contained enzymes able to depolymerize both crystalline and soluble celluloses and xylans. Higher cellulase and xylanase activities were found in the cell-free culture supernatant of the strain when grown on microcrystalline cellulose than when grown on xylan. Total cellulase and endoglucanase [carboxymethyl-cellulase (CMCase)] activities reached maxima after 72 h and xylanase activity was maximal after 60h. Temperature and pH optima were 55°C and 5.0 for CMCase activity and 60°C and 5.5 for total crystalline cellulase and xylanase activities. At 80°C, approximate half-lives of the enzymes were 37, 81 and 51 min for CMCase, crystalline cellulose depolymerization and xylanase, respectively.