Bacillus tianshenii sp. nov., isolated from a marine sediment sample

Sutcliffiella rhizosphaerae sp. nov. isolated from roots

An aerobic, Gram-staining-positive, endospore-forming bacterium, isolated from the rhizosphere of roots of maize (Zea mays), was taxonomically studied. On the basis of 16S rRNA gene sequence similarity comparisons, strain JJ-125T clustered together with species of the genus Sutcliffiella and showed the highest similarities with Sutcliffiella zhanjiangensis (98.7 %). The 16S rRNA gene sequence similarities to the sequences of the type strains of other species of the genus Sutcliffiella were <98.4 %. The genome sequence of JJ-125T was 4 516 360 bp long and had a DNA G+C content of 37.3 %. A DNA–DNA hybridization with the type strain of S. zhanjiangensis DSM 23010T resulted in values of 42.3 and 43.9 % (reciprocal). The average nucleotide identity, average amino acid identity and digital DNA–DNA hybridization values between the JJ-125T genome assembly and those of the other type strains of species of the genus Sutcliffiella were <75%, <80 % and <21 %, respectively. Chemotaxonomic features supported the grouping of the strain with the genus Sutcliffiella, e.g. the major fatty acids included iso-C15 : 0, iso-C17 : 1 ω10c and iso-C17 : 0, the polar lipid profile contained the major components diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine, the only quinone was menaquinone MK-7 and the characteristic diamino acid was meso-diaminopimelic acid. Physiological and biochemical test results were also different from those of the most closely related species. As a consequence, JJ-125T represents a novel species of the genus Sutcliffiella , for which we propose the name Sutcliffiella rhizosphaerae sp. nov., with JJ-125T (= CIP 111883T = LMG 32156T = CCM 9046T) as the type strain.

Metabacillus schmidteae sp. nov., Cultivated from Planarian Schmidtea mediterranea Microbiota

Taxonogenomics combines phenotypic assays and genomic analysis as a means of characterizing novel strains. We used this strategy to study Marseille-P9898T strain, an aerobic, motile, Gram-negative, spore-forming, and rod-shaped bacterium isolated from planarian Schmidtea mediterranea. Marseille-P9898T is catalase-positive and oxidase-negative. The major fatty acids detected are 12-methyl-tetradecanoic acid, 13-methyl-tetradecanoic acid, and hexadecanoic acid. Marseille-P9898T strain shared more than 98% sequence similarity with the Metabacillus niabensis strain 4T19T (98.99%), Metabacillus halosaccharovorans strain E33T (98.75%), Metabacillus malikii strain NCCP-662T (98.19%), and Metabacillus litoralis strain SW-211T (97.15%). Marseille-P9898 strain belongs to Metabacillus genus. Genomic analysis revealed the highest similarities with Ortho-ANI and dDDH, 85.76% with Metabacillus halosaccharovorans, and 34.20% with Bacillus acidicola, respectively. These results show that the Marseille-P9898T strain is a novel bacterial species from Metabacillus genus, for which we propose the name of Metabacillus schmidteae sp. nov. (Type strain Marseille-P9898T = CSUR P9898T = DSM 111480T).

Comparative genomics study reveals Red Sea Bacillus with characteristics associated with potential microbial cell factories (MCFs)

Recent advancements in the use of microbial cells for scalable production of industrial enzymes encourage exploring new environments for efficient microbial cell factories (MCFs). Here, through a comparison study, ten newly sequenced Bacillus species, isolated from the Rabigh Harbor Lagoon on the Red Sea shoreline, were evaluated for their potential use as MCFs. Phylogenetic analysis of 40 representative genomes with phylogenetic relevance, including the ten Red Sea species, showed that the Red Sea species come from several colonization events and are not the result of a single colonization followed by speciation. Moreover, clustering reactions in reconstruct metabolic networks of these Bacillus species revealed that three metabolic clades do not fit the phylogenetic tree, a sign of convergent evolution of the metabolism of these species in response to special environmental adaptation. We further showed Red Sea strains Bacillus paralicheniformis (Bac48) and B. halosaccharovorans (Bac94) had twice as much secreted proteins than the model strain B. subtilis 168. Also, Bac94 was enriched with genes associated with the Tat and Sec protein secretion system and Bac48 has a hybrid PKS/NRPS cluster that is part of a horizontally transferred genomic region. These properties collectively hint towards the potential use of Red Sea Bacillus as efficient protein secreting microbial hosts, and that this characteristic of these strains may be a consequence of the unique ecological features of the isolation environment.

Marinobacter sp. from marine sediments produce highly stable surface-active agents for combatting marine oil spills

Background

The application of chemical dispersants as a response to marine oil spills is raising concerns related to their potential toxicity also towards microbes involved in oil biodegradation. Hence, oil spills occurring under marine environments necessitate the application of biodispersants that are highly active, stable and effective under marine environment context. Biosurfactants from marine bacteria could be good candidates for the development of biodispersant formulations effective in marine environment. This study aimed at establishing a collection of marine bacteria able to produce surface-active compounds and evaluating the activity and stability of the produced compounds under conditions mimicking those found under marine environment context.

Results

A total of 43 different isolates were obtained from harbor sediments. Twenty-six of them produced mainly bioemulsifiers when glucose was used as carbon source and 16 were biosurfactant/bioemulsifiers producers after growth in the presence of soybean oil. Sequencing of 16S rRNA gene classified most isolates into the genus Marinobacter. The produced emulsions were shown to be stable up to 30 months monitoring period, in the presence of 300 g/l NaCl, at 4 °C and after high temperature treatment (120 °C for 20 min). The partially purified compounds obtained after growth on soybean oil-based media exhibited low toxicity towards V. fischeri and high capability to disperse crude oil on synthetic marine water.

Conclusions

To the best of our knowledge, stability characterization of bioemulsifiers/biosurfactants from the non-pathogenic marine bacterium Marinobacter has not been previously reported. The produced compounds were shown to have potential for different applications including the environmental sector. Indeed, their high stability in the presence of high salt concentration and low temperature, conditions characterizing the marine environment, the capability to disperse crude oil and the low ecotoxicity makes them interesting for the development of biodispersants to be used in combatting marine oil spills.

Electronic supplementary material

The online version of this article (10.1186/s12934-017-0797-3) contains supplementary material, which is available to authorized users.

Bacillus iocasae sp. nov., isolated from Pacmanus hydrothermal field, Manus Basin

A novel bacterial strain S36T was isolated from the deep-sea sediment collected from Pacmanus hydrothermal field, Manus Basin. The strain was Gram-stain-positive, aerobic, rod-shaped, endospore-forming, and motile. It was able to grow at 16-50 °C, pH 6.0-10.0, and in the presence of 0-11 % (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequence indicated that strain S36T was a member of genus Bacillus and shares the highest sequence identity with Bacillus herbersteinensis D-1,5aT (97.0 %). The value of DNA-DNA hybridization between strain S36T and B. herbersteinensis D-1,5aT was 22.8 %. The cell wall diagnostic diamino acid of strain S36T was meso-diaminopimelic acid and the polar lipid profile of strain S36T contained diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine. The predominant respiratory quinine was MK-7. The major cellular fatty acids were iso-C15 : 0 and anteiso-C15 : 0. The genomic DNA G+C content of strain S36T was 43.0 mol%. On the basis of phylogenetic analysis, DNA-DNA hybridization, and phenotypic characteristics, it was concluded that strain S36T represents a novel species of the genus Bacillus, for which the name Bacillus iocasae sp. nov. was proposed. The type strain is S36T (=KCTC 33864T=DSM 104297T=CGMCC 1.16030T).

Role of fatty acids in Bacillus environmental adaptation

The large bacterial genus Bacillus is widely distributed in the environment and is able to colonize highly diverse niches. Some Bacillus species harbor pathogenic characteristics. The fatty acid (FA) composition is among the essential criteria used to define Bacillus species. Some elements of the FA pattern composition are common to Bacillus species, whereas others are specific and can be categorized in relation to the ecological niches of the species. Bacillus species are able to modify their FA patterns to adapt to a wide range of environmental changes, including changes in the growth medium, temperature, food processing conditions, and pH. Like many other Gram-positive bacteria, Bacillus strains display a well-defined FA synthesis II system that is equilibrated with a FA degradation pathway and regulated to efficiently respond to the needs of the cell. Like endogenous FAs, exogenous FAs may positively or negatively affect the survival of Bacillus vegetative cells and the spore germination ability in a given environment. Some of these exogenous FAs may provide a powerful strategy for preserving food against contamination by the Bacillus pathogenic strains responsible for foodborne illness.