Effects of adding lignocellulose-degrading microbial agents and biochar on nitrogen metabolism and microbial community succession during pig manure composting.

This study assessed the influence of the additions of lignocellulose-degrading microbial agents and biochar on nitrogen (N) metabolism and microbial community succession during pig manure composting. Four treatments were established: CK (without additives), M (lignocellulose-degrading microbial agents), BC (biochar), and MBC (lignocellulose-degrading microbial agents and biochar). The results revealed that all treatments with additives decreased N loss compared with CK. In particular, the concentrations of total N and NO3--N were the highest in M, which were 21.87% and 188.67% higher than CK, respectively. Meanwhile, the abundance of denitrifying bacteria Flavobacterium, Enterobacter, and Devosia reduced with additives. The roles of Anseongella (nitrifying bacterium) and Nitrosomonas (ammonia-oxidizing bacterium) in NO3--N transformation were enhanced in M and BC, respectively. N metabolism pathway prediction indicated that lignocellulose-degrading microbial agents addition could enhance N retention effectively mainly by inhibiting denitrification. The addition of biochar enhanced oxidation of NH4+-N to NO2--N and N fixation, as well as inhibited denitrification. These results revealed that the addition of lignocellulose-degrading microbial agents individually was more conducive to improve N retention in pig manure compost.

[Isolation, identification, and degradation characteristics of three effective PAHs degradation strains]. / 3æ ªå¤šçŽ¯èŠ³çƒƒé«˜æ•ˆé™è§£èŒæ ªçš„åˆ†ç¦»é‰´å®šåŠé™è§£ç‰¹æ€§.

Isolating dominant strains for the degradation of polycyclic aromatic hydrocarbons (PAHs) is of great practical significance for the restoration of ecosystem polluted by PAHs. A total of 11 strains with capacity of degrading PAHs were obtained from soil polluted by PAHs around a coking plant, by enrichment culture, acclimation, and plate isolation. Three of them with effective PAH-degrading capability were identified and screened out by morphological observation, physiobiochemical characterization, and 16S rRNA gene sequencing, and respectively, named as DJ-3, DJ-8 and DJ-10. Based on the results of 16S rRNA gene sequencing, DJ-3, DJ-8, and DJ-10 were identified as Pseudomonas sp. Klebsiella sp., and Bacillus sp. The degradation rate of phenanthrene (200 mg·L-1), pyrene (200 mg·L-1), and naphthol (160 mg·L-1) by three strains (DJ-3, DJ-8 and DJ-10) after seven-day incubation were 48.9%-65.9%, 38.9%-43.1%, and 57.6%-64.9%, respectively. The degradation rates of mixed PAHs sample (1200 mg·L-1) by three strains were 49.1%, 44.5%, and 53.9%, which were significantly higher than other eight strains, indicating that they were highly effective in PAHs degradation. There was no antagonistic relationship among the three strains. This study would lay a foundation for building efficient PAHs degrading strains and improve the in situ bioremediation of PAHs contaminated soil.

Effects of fertilization and reclamation time on soil bacterial communities in coal mining subsidence areas.

Land impaired by mining activity can be restored to a productive and healthy state through a variety of reclamation methods. Fertilization is one effective method to improve soil fertility and microbial activity. However, the effects of fertilization and reclamation time on bacterial communities in reclaimed soil remain unclear. Here, we hypothesized that both fertilization and reclamation time could promote restoration of reclaimed soil. To test this, soil properties and bacterial communities in a reclaimed coal mining subsidence area were investigated under different fertilizer regimes and different reclamation times. Compared with no fertilization treatment, fertilization rapidly improved the soil nutrients and bacterial α-diversity, both of which exhibited no significant differences between chemical fertilizer and organic fertilizer. With increasing of reclamation time, the soil nutrient levels (soil organic matter, available nitrogen, available phosphorus, available potassium) and the bacterial diversity increased. Meanwhile, the relative abundances of Proteobacteria, Actinobacteria and Bacteroidetes increased, and the relative abundances of Acidobacteria, Chloroflexi and Nitrospirae decreased. Compared with the 1-year and 3-year reclaimed soils, the soil nutrients and bacterial community structure in the 7-year reclaimed soils were more similar to those in the undisturbed soils. In conclusion, reclamation time is the main driving force for the restoration of soil properties and bacterial communities in mining areas, and fertilization can shorten the recovery time of the reclaimed soil.

A Chemical Counterpunch: Chromobacterium violaceum ATCC 31532 Produces Violacein in Response to Translation-Inhibiting Antibiotics.

Antibiotics produced by bacteria play important roles in microbial interactions and competition Antibiosis can induce resistance mechanisms in target organisms, and at sublethal doses, antibiotics have been shown to globally alter gene expression patterns. Here, we show that hygromycin A from Streptomyces sp. strain 2AW. induces Chromobacterium violaceum ATCC 31532 to produce the purple antibiotic violacein. Sublethal doses of other antibiotics that similarly target the polypeptide elongation step of translation likewise induced violacein production, unlike antibiotics with different targets. C. violaceum biofilm formation and virulence against Drosophila melanogaster were also induced by translation-inhibiting antibiotics, and we identified an antibiotic-induced response (air) two-component regulatory system that is required for these responses. Genetic analyses indicated a connection between the Air system, quorum-dependent signaling, and the negative regulator VioS, leading us to propose a model for induction of violacein production. This work suggests a novel mechanism of interspecies interaction in which a bacterium produces an antibiotic in response to inhibition by another bacterium and supports the role of antibiotics as signal molecules.IMPORTANCE Secondary metabolites play important roles in microbial communities, but their natural functions are often unknown and may be more complex than appreciated. While compounds with antibiotic activity are often assumed to underlie microbial competition, they may alternatively act as signal molecules. In either scenario, microorganisms might evolve responses to sublethal concentrations of these metabolites, either to protect themselves from inhibition or to change certain behaviors in response to the local abundance of another species. Here, we report that violacein production by C. violaceum ATCC 31532 is induced in response to hygromycin A from Streptomyces sp. 2AW, and we show that this response is dependent on inhibition of translational polypeptide elongation and a previously uncharacterized two-component regulatory system. The breadth of the transcriptional response beyond violacein induction suggests a surprisingly complex metabolite-mediated microbe-microbe interaction and supports the hypothesis that antibiotics evolved as signal molecules. These novel insights will inform predictive models of soil community dynamics and the unintended effects of clinical antibiotic administration.

Spent Ganoderma lucidum substrate derived biochar as a new bio-adsorbent for Pb2+/Cd2+ removal in water.

The present study firstly reports spent Ganoderma lucidum substrate derived biochars (SLBCS) for the effective removal of Pb2+/Cd2+ from water. The effects of pyrolysis temperature on the SLBCS characteristics and Pb2+/Cd2+ adsorption mechanism was studied systematically. The surface physicochemical properties of SLBCS were significantly affected by the pyrolysis temperature. The increase in pyrolysis temperature from 250 to 650 °C resulted in a drastic increase in the biochar surface area and the well development of mesoporous structure, which could provide more effective adsorption sites for Pb2+ and Cd2+ onto SLBCS. According to the Langmuir model, the obtained maximum adsorption capacity of Pb2+ onto SL650 reached 262.76 mg g-1, while that of Cd2+ reached 75.82 mg g-1. The adsorption capacities of SL650 for Pb2+ and Cd2+ were even higher than that of other modified biochars. The high adsorption capacity of SL650 for Pb2+, attributed to the precipitation supported by high temperature, benefitted the formation of carbonate minerals. Two possible mechanisms involved in Cd2+ sorption: carbonate precipitation and coordination with π electrons. Desorption of SL650 showed high efficiency for Pb2+, but slightly low efficiency for Cd2+. These results indicate that SL650 can be applied for removing heavy metals, especially Pb2+, from polluted water.

Influence of cell disruption and elution on cellulase release of Clostridium straminisolvens (CSK1).

Clostridium straminisolvens (CSK1) is a novel cellulolytic bacterium isolated from a cellulose-degrading bacterial community MC1. In this study, the influence of the following cell disruption and elution methods on CSK1cellulase release was investigated: (1) freezing-thawing, (2) ultrasonication, (3) elution, (4) freezing-thawing following elution, (5) ultrasonication following elution, and lastly (6) high-pressure homogenization following elution. The activity of the cellulases CMCase, ß-glucosidase, Avicelase, FPase, and xylanase in crude extracts increased 81.5, 23.8, 87.7, 46.3, and 51.7 %, respectively, with an observed optimal treatment method for each cellulase type. The release of protein from CSK1 cells increased following either cell disruption or elution and was highest at 88.3 % in the homogenization high pressure following elution treatment. A newly observed protein was present following cell elution. The performance of cell elution as determined by real time-PCR indicated that the first time cell elution removed more than 90 % of the CSK1 cells from the substrate. These findings demonstrate that cell disruption and elution are effective methods for inducing cellulase release, and elution is the key step for CSK1. To our knowledge, this study presents the first evidence of optimal treatments for induction of cellulase release of Clostridium straminisolvens. This information will be of great value for use in subsequent efforts to better understand the cellulase characteristics of CSK1 and cellulose degradation mechanisms of the MC1 community.

Dynamic changes in the composite microbial system MC1 during and following its rapid degradation of lignocellulose.

To monitor the dynamics of the composite microbial system MC1 during its degradation of lignocellulose and to improve our understanding of the microbial communities involved in this biomass conversion, MC1 was characterized at eight time points over an 18-day, thermophilic, aerobic, static cultivation. We found the microbial communities to be dynamic, rhythmic consortia capable of changing in response to lignocellulose degradation. The growth curve over 18 days was M-shaped. Based on the quantitative changes in five major components of MC1 (Clostridium straminisolvens CSK-1, Clostridium sp. FG4, Pseudoxanthomonas sp. M1-3, Brevibacillus sp. M1-5, and Bordetella sp. M1-6), reduction in rice straw weight, cellulase (CMCase) activity, xylanase activity, and changes in medium pH, we found that the process comprised two identifiable phases. Rapid degradation occurred from day 0 to day 9, while the post-rapid degradation phase included days 10 to 18. Day 3 and day 12 were two key time points in the rapid degradation phase and post-rapid degradation phase, respectively. Two anaerobes, C. straminisolvens CSK-1 and Clostridium sp. FG4, dominated the MC1 system from day 0 to day 18.

Optimization of liquid fermentation of microbial consortium WSD-5 followed by saccharification and acidification of wheat straw.

The microbial consortium WSD-5 is composed of bacteria and fungi, and the cooperation and symbiosis of the contained microbes enhance the degradation ability of WSD-5. Experiment results showed that the highest cellulase and hemicellulase were obtained when ventilation volume was 4 L/min, stirring rate was 0 rpm, and substrate loading rate was 3%. After 6 days of cultivation, a 67.60% loss in wheat straw dry weight was observed. The crude enzyme secreted from WSD-5 after optimization was evaluated by experiments of saccharification and acidification. The maximum concentration of reducing sugars was 3254 mg/L after 48 h saccharification. The concentration of sCOD peaked on day 2 with a value of 4345 mg/L during acidification, and the biogas yield and methane yield were 22.3% and 32.3% higher than un-acidified samples. This study is the first attempt to explore both the saccharification and the acidification ability of crude enzymes secreted by microbial consortium.

Effect of pretreatment by a microbial consortium on methane production of waste paper and cardboard.

A microbial consortium MC1 was used to pretreat filter paper, office paper, newspaper, and cardboard to enhance methane production. The results of pretreatment indicated that sCOD of hydrolysates of the four substrates increased significantly in the early stage, and peaked on day 7. During pretreatment, ethanol, acetic acid, propionic acid, butyric acid, and glycerol were the predominant volatile organic products in hydrolysates. MC1 had strong degradation ability on the four substrates, and the weight loss of filter paper, office paper, newspaper, and cardboard reached 78.3%, 80.5%, 39.7%, and 49.7%, respectively. The results of anaerobic digestion showed that methane production yields and rates of the four substrates significantly increased after pretreatment. This study is the first attempt to explore the microbial pretreatment method for anaerobic digestion of waste paper and cardboard. Microbial consortium pretreatment could be an effective method for enhancing methane production of waste paper and cardboard into bioenergy.