Thalassobacillus hwangdonensis sp. nov., isolated from a tidal flat sediment

New Insights into the Effect of Fipronil on the Soil Bacterial Community

Fipronil is a broad-spectrum insecticide with remarkable efficacy that is widely used to control insect pests around the world. However, its extensive use has led to increasing soil and water contamination. This fact is of concern and makes it necessary to evaluate the risk of undesirable effects on non-target microorganisms, such as the microbial community in water and/or soil. Studies using the metagenomic approach to assess the effects of fipronil on soil microbial communities are scarce. In this context, the present study was conducted to identify microorganisms that can biodegrade fipronil and that could be of great environmental interest. For this purpose, the targeted metabarcoding approach was performed in soil microcosms under two environmental conditions: fipronil exposure and control (without fipronil). After a 35-day soil microcosm period, the 16S ribosomal RNA (rRNA) gene of all samples was sequenced using the ion torrent personal genome machine (PGM) platform. Our study showed the presence of Proteobacteria, Actinobacteria, and Firmicutes in all of the samples; however, the presence of fipronil in the soil samples resulted in a significant increase in the concentration of bacteria from these phyla. The statistical results indicate that some bacterial genera benefited from soil exposure to fipronil, as in the case of bacteria from the genus Thalassobacillus, while others were affected, as in the case of bacteria from the genus Streptomyces. Overall, the results of this study provide a potential contribution of fipronil-degrading bacteria.

Thalassobacillus, a genus of extreme to moderate environmental halophiles with biotechnological potential

Thalassobacillus is a moderately halophilic genus that has been isolated from several sites worldwide, such as hypersaline lakes, saline soils, salt flats, and volcanic mud. Halophilic bacteria have provided functional stable biomolecules in harsh conditions for industrial purposes. Despite its potential biotechnological applications, Thalassobacillus has not been fully characterized yet. This review describes the Thalassobacillus genus, with the few species reported, pointing out its possible applications in enzymes (amylases, cellulases, xylanases, and others), biosurfactants, bioactive compounds, biofuels production, bioremediation, and plant growth promotion. The Thalassobacillus genus represents a little-explored biological resource but with a high potential.

Halalkalibacillus sediminis sp. nov., isolated from sediment of sea cucumber culture pond

A Gram-stain-positive, rod-shaped (0.3-0.4×1.2-2.0 µm), strictly aerobic and beige-pigmented bacterium, designated B3227^T, was isolated from the sediment of a sea cucumber culture pond in Rongcheng, China (122.2° E 36.9° N). Its biochemical characteristics analysis revealed that the cells of this bacterium were catalase-positive and oxidase-negative. Cell growth occurred at 15-45 °C (optimum, 37 °C), pH 6.5-9.0 (pH 7.5-8.0) and in the presence of 0.0-22.0 % (w/v) NaCl (6.0-9.0 % NaCl). Phylogenetic analysis based on 16S rRNA gene sequencing indicated that strain B3227^T exhibited similarities of 95.7, 95.5, 95.5 and 95.3 % to the type strains of Filobacillus milensis, Piscibacillus salipiscarius, Halalkalibacillus halophilus and Piscibacillus halophilus, respectively, and the results of physiological analyses revealed that strain B3227^T was most similar to the genus Halalkalibacillus. The cells were endospore-forming and comprised an A1-γ-meso-diaminopimelic acid-type peptidoglycan. The respiratory quinone of strain B3227^T was MK-7, and the dominant fatty acids were anteiso-C_15 : 0 and anteiso-C_17 : 0. The major polar lipids were diphosphatidylglycerol and phosphatidylethanolamine. The genomic DNA G+C content was 38.7 mol%. The average nucleotide identity values between strain B3227^T and H. halophilus JCM 14192^T (ANIb 69.5%, ANIm 84.2 %) and F. milensis JCM 12288^T (ANIb 70.1 %, ANIm 84.1 %) were below the cut-off level (95-96  %) for species delineation. The results of kegg analysis revealed that strain B3227^T could biosynthesize shikimate acid, a base compound for the formulation of the swine flu drug. Based on its morphological and physiological properties, as well as phylogenetic distinctiveness, strain B3227^T should be placed into the genus Halalkalibacillus as a representative of a new species, for which the name Halalkalibacillus sediminis sp. nov. is proposed. The type strain is B3227^T (=KCTC 33093^T=MCCC 1H00193^T).

Evolution in the Bacillaceae

The family Bacillaceae constitutes a phenotypically diverse and globally ubiquitous assemblage of bacteria. Investigation into how evolution has shaped, and continues to shape, this family has relied on several widely ranging approaches from classical taxonomy, ecological field studies, and evolution in soil microcosms to genomic-scale phylogenetics, laboratory, and directed evolution experiments. One unifying characteristic of the Bacillaceae , the endospore, poses unique challenges to answering questions regarding both the calculation of evolutionary rates and claims of extreme longevity in ancient environmental samples.

Thalassobacillus pellis sp. nov., a moderately halophilic, Gram-positive bacterium isolated from salted hides

A Gram-positive, moderately halophilic and endospore-forming bacterium, designated strain 18OM(T), was isolated from salted animal hides. The cells were rods and produced ellipsoidal endospores at a terminal position. Strain 18OM(T) was motile, strictly aerobic and grew at 0.5-25 % (w/v) NaCl [optimal growth at 10 % (w/v) NaCl], at between pH 5.0 and 9.0 (optimal growth at pH 7.5) and at temperatures between 15 and 45 °C (optimal growth at 37 °C). Phylogenetic analysis based on 16S rRNA gene sequence comparisons showed that strain 18OM(T) was closely related to species of the genus Thalassobacillus within the phylum Firmicutes. The closest phylogenetic similarity was with Thalassobacillus devorans G-19.1(T) (98.4 %), Thalassobacillus cyri HS286(T) (97.9 %) and Thalassobacillus hwangdonensis AD-1(T) (97.4 %). The major cellular fatty acids were anteiso-C(15 : 0) (57.9 %), anteiso-C(17 : 0) (14.0 %), iso-C(15 : 0) (10.8 %) and iso-C(16 : 0) (8.1 %). The respiratory isoprenoid quinones were MK-7 (98.5 %) and MK-6 (1.5 %). The DNA G+C content was 42.9 mol%. These features confirmed the placement of strain 18OM(T) within the genus Thalassobacillus. The DNA-DNA hybridization values between strain 18OM(T) and T. devorans G-19.1(T), T. cyri HS286(T) and T. hwangdonensis AD-1(T) were 49 %, 9 % and 15 %, respectively, showing unequivocally that strain 18OM(T) constituted a novel genospecies. On the basis of phylogenetic analysis and phenotypic, genotypic and chemotaxonomic characteristics, strain 18OM(T) is considered to represent a novel species of the genus Thalassobacillus, for which the name Thalassobacillus pellis sp. nov. is proposed. The type strain is 18OM(T) ( = CECT 7566(T) = DSM 22784(T) = JCM 16412(T)).