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Purpose Coal mining activities result in large-scale soil degradation and ecosystem imbalances in many countries. Fertilization is an effective way to improve soil fertility and microbial activity. However, the effect of different fertilizers and remediation time on the subsided soil is not clear. The aim of this study is to explore the effects on soil fertility and the bacterial community. Methods In this study, we compared three fertilization regimes (inorganic, organic, and combined) applied over a 5-year period for the purpose of rehabilitating subsoil through measurement of soil’s chemical properties and microbial biomass. Bacterial diversity was evaluated in different reclaimed soils via high-throughput 16S rDNA sequencing; 1,938,561 total sequences were obtained. Results The results showed that fertilization improved various soil properties, including the concentrations of available phosphorus, available potassium, and alkali-hydrolysable nitrogen, therefore, increasing microbial biomass. A significant increase in soil microbial diversity was observed in fertilized soils compared to the initial conditions. A positive correlation between microbial diversity and soil properties was observed. Regarding an improvement in soil properties and crop yields, the organic fertilizer demonstrated significantly more effectiveness compared to the inorganic fertilizer. Meanwhile, the relative abundance of Proteobacteria, Bacteroidetes, and Verrucomicrobia increased, but the relative abundance of Chloroflexi and Nitrospirae decreased. More specifically, we found that several Proteobacteria subgroups, such as Rhizobiales, Myxococcales, Sphingomonadales, Rhodospirillales, Xanthomonadales, and Burkholderiales, increased after the restoration. Additionally, the composition of the bacterial community in the 5-year groups (M5, O5, and MO5) was similar to the composition of the FS group, and the yield of the maize test crop following the 5-year restoration period was close to the average in China. Conclusion This result indicates that soil reclamation via fertilization can contribute to soil recovery over time. Therefore, we concluded that fertilization is an effective strategy for the restoration of soil properties and bacterial communities in mining soil.

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., 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.

The present study firstly reports spent Ganoderma lucidum substrate derived biochars (SLBCS) for the effective removal of Pb

Bacterially produced antibiotics play important roles in microbial interactions and competition. Antibiosis can induce resistance mechanisms in target organisms and may induce other countermeasures as well. Here, we show that hygromycin A fromStreptomycessp. 2AW inducesChromobacterium violaceumATCC31532 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. violaceumbiofilm formation and virulence againstDrosophila melanogasterwere also induced by translation-inhibiting antibiotics, and we identified anantibiotic-inducedresponse (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.

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.

The recovery of the belowground microbial community structure and diversity that occurs in long-term coal mining reclamation is critical to reclamation success. However, long-term coal mining reclamation can take ~10–30 years. Therefore, finding an effective method for promoting coal mine soil restoration in the short-term is necessary to minimise reclamation time. This study investigated the response of soil bacterial communities to fertilisation along a chronosequence of short-term reclamation. Fertilised and unfertilised soils with three short-term reclamation stages were examined to characterise soil properties, as well as bacterial structure and diversity. Fertilisation promoted available nitrogen, phosphate, potassium, and soil organic matter, as well as benefits in bacterial community diversity across the three stages, with the most beneficial effects at 7 years. 16S rRNA sequencing data showed that the predominant phyla across all soils were Proteobacteria, Actinobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, and Gemmatimonadetes. Abundance of each phylum was altered by reclamation time and fertilisation. Clustering and functional analysis indicated that the bacterial community structure in soils with a longer reclamation time was more similar to that in natural soils, suggesting that longer reclamation resulted in increased soil activity and bacterial community diversity, which is likely also true for fertilisation. Our results demonstrate that reclamation duration is the main driving force to recover soil properties and bacterial communities, and fertilisation could enhance the beneficial effects with longer reclamation duration. Therefore, short-term reclamation, combined with fertiliser, is a potential strategy to improve soil conditions in coal mine areas and shorten the recovery time of reclaimed soils.

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.

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.

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.

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, β-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.

Microbial characteristics in the up-flow anaerobic sludge blanket reactor (UASB) of a full-scale high concentration cassava alcohol wastewater plant capable of anaerobic hydrocarbon removal were analyzed using cultivation-independent molecular methods. Forty-five bacterial operational taxonomic units (OTUs) and 24 archaeal OTUs were identified by building 16S rRNA gene of bacterial and archaeal clone libraries. Most bacterial OTUs were identified as phyla of Firmicutes (53.3%), Chloroflexi (20.0%), Proteobacteria (11.1%), Bacteroidetes (6.7%) and a candidate division (2.2%). Methanosaeta (57.5%) were the most abundant archaeal group, followed by Methanobacterium (10.6%), Methanomethylovorans (8.5%) and Methanosarcina (6.4%). Most bacterial species take charge of cellulolysis, proteolysis, acidogenesis and homo-acetogenesis; the most methanogens were typical hydrogenotrophic or hydrogenotrophic/aceticlastic. This study revealed a succession of both bacterial and archaeal populations during the trial, which could be linked to operational adaptation of high concentration organic cassava wastewater.Keywords: Full-scale, anaerobic reactor, 16S rRNA gene clone library, microbial diversity, functional analysis.