Composting is viewed as one of the primary methods to treat organic wastes. Co-composting may improve the efficiency of this treatment by establishing the most suitable conditions for decomposers than those present in the individual wastes. Given that bacteria and fungi are the driving agents of composting, information about the composition of their communities and dynamics during composting may improve reproducibility, performance and quality of the final compost as well as help to evaluate the potential human health risk and the choice of the most appropriate application procedure. In this study, the co-composting of mixtures containing two similar components (organic fraction of municipal solid waste and sawdust polluted by oil) and one discriminate component (sewage sludges of different origin) were investigated. Bacterial and fungal community successions in the two mixtures were analyzed during the composting process by determining the change in their structural dynamics using qPCR and 454 pyrosequencing methods in a lab experiment for a period of 270 days. During the initial composting stage, the number of 16S bacterial copies was (3.0±0.2) x 106 and (0.4±0.0) x 107 g-1, and the Rhodospiralles and Lactobacialles orders dominated. Fungal communities had (2.9±0.0) x105 and (6.1±0.2) x105 ITS copies g-1, and the Saccharomycetales order dominated. At the end of the thermophilic stage on the 30th day of composting, bacterial and fungal communities underwent significant changes: dominants changed and their relative abundance decreased. Typical compost residents included Flavobacteriales, Chitinophagaceae and Bacterioidetes for bacteria and Microascaceae, Dothideomycetes, Eurotiomycetes, Sordariomycetes, and Agaricomycetes for fungi. During the later composting stages, the dominating taxa of both bacterial and fungal communities remained, while their relative abundance decreased. In accordance with the change in the dominating OTUs, it was concluded that the dynamics of the bacterial and fungal communities were not similar. Analysis by non-metric multidimensional scaling (NMDS) revealed that the bacterial communities of the two composts became progressively more similar; a similar trend was followed by the fungal community.

Petroleum pollution of soils is a major environmental problem. Soil microorganisms can decompose a significant fraction of petroleum hydrocarbons in soil at low concentrations (1–5%). This characteristic can be used for soil remediation after oil pollution. Microbial community dynamics and functions are well studied in cases of moderate petroleum pollution, while cases with heavy soil pollution have received much less attention. We studied bacterial and fungal successions in three different soils with high petroleum contents (6 and 25%) in a laboratory experiment. The proportion of aliphatic and aromatic compounds decreased by 4–7% in samples with 6% pollution after 120 days of incubation but remained unchanged in samples with 25% hydrocarbons. The composition of the microbial community changed significantly in all cases. Oil pollution led to an increase in the relative abundance of bacteria such as Actinobacteria and the candidate TM7 phylum (Saccaribacteria) and to a decrease in that of Bacteroidetes. The gene abundance (number of OTUs) of oil-degrading bacteria (Rhodococcus sp., candidate class TM7-3 representative) became dominant in all soil samples, irrespective of the petroleum pollution level and soil type. The fungal communities in unpolluted soil samples differed more significantly than the bacterial communities. Nonmetric multidimensional scaling revealed that in the polluted soil, successions of fungal communities differed between soils, in contrast to bacterial communities. However, these successions showed similar trends: fungi capable of lignin and cellulose decomposition, e.g., from the genera Fusarium and Mortierella, were dominant during the incubation period.

Background and AimsAlthough soil-inhabiting fungi can affect tree health and biomass production in managed and pristine forests, little is known about the sensitivity of the plant-fungal associations to long-term changes in land use. We aimed to investigate how reforestation of farmlands change soil characteristics and affected the recovery of soil fungal functional guilds. MethodsWe examined edaphic conditions and fungal communities (Illumina Sequencing) in three land-use types: primary forests (PF), secondary forests (SF, established over two decades ago) and active farmlands during May, July and September in Wuying, China. ResultsEdaphic conditions and general fungal communities varied with land-use. Interestingly, overall fungal diversity was higher in soils at the farmland than at the forested sites, possibly as a result of recurring disturbances (tilling) allowing competitive release as described by the intermediate disturbance hypothesis. Although ectomycorrhizal fungal diversity and richness were marginally higher in PF than in SF, the latter still hosted surprisingly diverse and abundant ectomycorrhizal fungal communities. ConclusionsReforestation largely restored fungal communities that were still in transition, as their composition in SF was distinct from that in PF. Our results highlight the ability of fungi grown in previously strongly managed agricultural land to rapidly respond to reforestation and thus provide support for forest trees.

Abstract. Oil wastes produced in large amounts in the processes of oil extraction, refining, and transportation are of great environmental concern because of their mutagenicity, toxicity, high fire hazardousness, and hydrophobicity. About 40 % of these wastes contain radionuclides; however, the ef-

Because of significant yield losses caused by fungal pathogens, new efficient and environmentally safe methods of pest control are needed, and amphiphilic compounds (biosurfactants) produced by many microbes are considered a good alternative. In the present study, biosurfactants produced by the rhizosphere isolate Bacillus mojavensis P1709 were assessed for their ability to protect postharvest cherry tomatoes from decay and mycotoxin contamination caused by Fusarium oxysporum f. sp. lycopersici. It was demonstrated that the genome of B. mojavensis P1709 contained the fenD and srfAA genes, which are responsible for the synthesis of compounds of the fengycin and surfactin families. APF (acid-precipitated fraction) of B. mojavensis P1709 culture medium at a concentration of 20 g L−1 inhibited pathogen radial growth on agar plates by 93%, and T-2 and HT-2 mycotoxin production by 98%, after 5 days of cultivation. APF also suppressed fungal growth in the in vivo test on cherry tomato fruits by 93% and 25% on the 2nd and 7th days of incubation, respectively. The results obtained demonstrate that biosurfactants produced by B. mojavensis P1709 are an efficient tool for protecting postharvest cherry tomatoes from fungal mold decay and mycotoxin contamination.