SUMMARY This paper presents the results of the study on the production of protease by Bacillus luteus H11 isolated from an alkaline soda lime. B. luteus H11 was identified as an alkalohalophilic bacterium, and its extracellular serine endoprotease also showed an extreme alkali- and halotolerance. It was remarkably stable in the presence of NaCl up to 5 M. The enzyme was active in a broad range of pH values and temperatures, with an optimum pH of 10.5 and a temperature of 45 °C. It had a molecular mass of about 37 kDa and showed activity against azocasein and a synthetic substrate for the subtilisin-like protease, N-succinyl- l -phenylalanine- p -nitroanilide. The halo-alkaline protease produced by B. luteus H11 seems to be significant from an industrial perspective because of its tolerance towards high salinity and alkalinity as well as its stability against some organic solvents, surfactants and oxidants. These properties make the protease suitable for applications in food, detergent and pharmaceutical industries, and also in environmental bioremediation.

The present research was aimed at assessing the quality of air in work environment of the municipal landfill site in Toru n. Air samples were collected in the outdoor space (operating landfill cell, technological square), and in indoor space (sorting station, weighing station, social room) using the impaction method. The microbiological air testing included determining the number of airborne mesophilic bacteria and molds. Bacterial strains were identified with appropriate API tests; molds were identified according to their macro and micro characteristics. In outdoor air, the highest average concentration of mesophilic bacteria were recorded at the operating landfill cell (1361 colony forming unit (CFU)/m 3 ). The highest average concentrations of molds were recorded at the technological square (1179 CFU/m 3 ). In indoor air, the highest average concentration of investigated microorganisms (bacteria: 10 707 CFU/m 3 , molds:12 471 CFU/m 3 ) were recorded in the sorting facility. The concentration of microorganisms in the outdoor air depended on the season (p < 0.05), but did not depend on the sampling site, while in the indoor air depended on the sampling site (p < 0.05) but did not depend on the season. Bioaerosol emitted in municipal facility was the source of bacterial (Bacillus subtilis, Pseudomonas aeruginosa) and fungal species (Aspergillus fumigatus, Madurella grisea, Penicillium manfferei, Scedosporium apiospermium, Cryptococcus neoformans), posing a health risk for humans. However Gram-negative bacteria constituted only a small fraction of the isolated microorganisms. The highest risk of exposure to biological agents was determined in the sorting station. The majority of the outdoor air samples were classified as uncontaminated. The results emphasize the need for regular monitoring of microbiological tests in indoor and outdoor air of municipal landfill sites as well as for control strategies in order to protect workers at landfill.

Soda lime is a by-product of the Solvay soda process for the production of sodium carbonate from limestone and sodium chloride. Due to a high salt concentration and alkaline pH, the lime is considered as a potential habitat of haloalkaliphilic and haloalkalitolerant microbial communities. This artificial and unique environment is nutrient-poor and devoid of vegetation, due in part to semi-arid, saline and alkaline conditions. Samples taken from the surface layer of the lime and from the depth of 2 m (both having pH ~11 and ECe up to 423 dS m−1) were investigated using culture-based (culturing on alkaline medium) and culture-independent microbiological approaches (microscopic analyses and pyrosequencing). A surprisingly diverse bacterial community was discovered in this highly saline, alkaline and nutrient-poor environment, with the bacterial phyla Proteobacteria (representing 52.8% of the total bacterial community) and Firmicutes (16.6%) showing dominance. Compared to the surface layer, higher bacterial abundance and diversity values were detected in the deep zone, where more stable environmental conditions may occur. The surface layer was dominated by members of the genera Phenylobacterium, Chelativorans and Skermanella, while in the interior layer the genus Fictibacillus was dominant. The culturable aerobic, haloalkaliphilic bacteria strains isolated in this study belonged mostly to the genus Bacillus and were closely related to the species Bacillus pseudofirmus, B. cereus, B. plakortidis, B. thuringensis and B. pumilus.Electronic supplementary materialThe online version of this article (doi:10.1007/s10482-017-0866-y) contains supplementary material, which is available to authorized users.

Intraterrestrial waters harbor microbial communities being extensively studied to understand microbial processes underlying subsurface ecosystem functioning. This paper provides the results of an investigation on the microbiomes of unique, subsurface sulfidic waters associated with Upper Jurassic, Cretaceous, and Miocene sediments. We used high-throughput 16S rDNA amplicon sequencing to reveal the structure of bacterial and archaeal communities in water samples differing in sulfide content (20–960 mg/dm 3 ), salinity (1.3–3.2%), and depth of extraction (60–660 m below ground level). Composition of the bacterial communities strongly varied across the samples; however, the bacteria participating in the sulfur cycle were common in all sulfidic waters. The shallowest borehole water (60 m bgl) was dominated by sulfur-oxidizing Epsilonproteobacteria ( Sulfurimonas , Sulfurovum ). In the waters collected from greater depths (148–300 m bgl), the prevalence of Betaproteobacteria ( Comamonadaceae ) and sulfate/sulfur-reducing Deltaproteobacteria ( Desulfopila , Desulfomicrobium , MSBL7 ) was observed. Sulfate reducers (members of Clostridia : Candidatus Desulforudis ) were the most abundant bacteria in the deepest borehole water (660 m bgl). Out of 850 bacterial OTUs, only one, affiliated with the Comamonadaceae family, was found abundant (> 1% of total bacterial sequences) in all samples. Contribution of Archaea to the whole microbial communities was lower than 0.5%. Archaeal communities did not differ across the samples and they consisted of Halobacteriaceae . Out of 372 archaeal OTUs, five, belonging to the four genera Natronomonas , Halorubrum , Halobellus , and Halorhabdus , were the most numerous. Electronic supplementary material The online version of this article (10.1007/s00248-018-1270-5) contains supplementary material, which is available to authorized users.

This study focused on the potential relationships between midgut microbiota of the common cockchafer Melolontha melolontha larvae and their resistance to entomopathogenic nematodes (EPN) infection. We investigated the bacterial community associated with control and unsusceptible EPN-exposed insects through nanopore sequencing of the 16S rRNA gene. Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the most abundant bacterial phyla within the complex and variable midgut microbiota of the wild M. melolontha larvae. The core microbiota was found to include 82 genera, which accounted for 3.4% of the total number of identified genera. The EPN-resistant larvae differed significantly from the control ones in the abundance of many genera belonging to the Actinomycetales, Rhizobiales, and Clostridiales orders. Additionally, the analysis of the microbiome networks revealed different sets of keystone midgut bacterial genera between these two groups of insects, indicating differences in the mutual interactions between bacteria. Finally, we detected Xenorhabdus and Photorhabdus as gut residents and various bacterial species exhibiting antagonistic activity against these entomopathogens. This study paves the way to further research aimed at unravelling the role of the host gut microbiota on the output of EPN infection, which may contribute to enhancement of the efficiency of nematodes used in eco-friendly pest management.