Halobacillus fulvus sp. nov., a moderately halophilic bacterium isolated from shrimp paste (Ka-pi) in Thailand

An aerobic, Gram-stain-positive, endospore-forming, rod-shaped and moderately halophilic strain SKP4-6T, was isolated from shrimp paste (Ka-pi) collected from Samut Sakhon Province, Thailand. Phylogenetic analysis revealed that strain SKP4-6T belonged to the genus Halobacillus and was most closely related to Halobacillus salinus JCM 11546T (98.6 %), Halobacillus locisalis KCTC 3788T (98.6 %) and Halobacillus yeomjeoni KCTC 3957T (98.6 %) based on 16S rRNA gene sequence similarity. The digital DNA–DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strain SKP4-6T and its related species were 18.2–19.3 % and 69.84–84.51 %, respectively, which were lower than the threshold recommended for species delineation. The strain grew optimally at 30–40 °C, at pH 7.0 and with 10–15 % (w/v) NaCl. It contained l-Orn–d-Asp in the cell wall peptidoglycan. The DNA G+C content was 44.8 mol%. The major fatty acids were iso-C15 : 0, anteiso-C15 : 0 and anteiso-C17 : 0. The predominant isoprenoid quinone was MK-7. Phosphatidylglycerol and diphosphatidylglycerol were present as major polar lipids. Based on this polyphasic approach, digital DNA–DNA relatedness and ANI values, strain SKP4-6T represents a novel species of the genus Halobacillus , for which the name Halobacillus fulvus sp. nov. is proposed. The type strain is SKP4-6T (=JCM 32624T=TISTR 2595T).

Comparing the effect of zinc oxide and titanium dioxide nanoparticles on the ability of moderately halophilic bacteria to treat wastewater

This study evaluates the ability of moderately halophilic bacterial isolates (Serratia sp., Bacillus sp., Morganella sp., Citrobacter freundii and Lysinibacillus sp.) to treat polluted wastewater in the presence of nZnO and nTiO2 nanoparticles. In this study, bacteria isolates were able to take up nZnO and nTiO2 at concentrations ranging from 1 to 50 mg/L in the presence of higher DO uptake at up to 100% and 99%, respectively, while higher concentrations triggered a significant decrease. Individual halophilic bacteria exhibited a low COD removal efficiency in the presence of both metal oxide nanoparticles concentration ranged between 1 and 10 mg/L. At higher concentrations, they triggered COD release of up to − 60% concentration. Lastly, the test isolates also demonstrated significant nutrient removal efficiency in the following ranges: 23–65% for NO3− and 28–78% for PO43−. This study suggests that moderately halophilic bacteria are good candidates for the bioremediation of highly polluted wastewater containing low metal oxide nanoparticles.

Physiological response of the moderately halophilic psychrotolerant strain Chromohalobacter sp. N1 to salinity change and low temperature

The available information on de novo synthesized compatible solutes in response to high medium salinity by bacteria of the Chromohalobacter genus is limited to studies of the mesophilic moderately halophilic strain Chromohalobacter salexigens DSM 3043T. Therefore, there is a need for studies of representatives of other species of the Chromohalobacter genus of the Halomonadaceae family. A moderately halophilic psychrotolerant bacterium, strain N1, closely related to the species Chromohalobacter japonicus was isolated from the salt crust of a rock salt waste pile in Berezniki, Perm Krai, Russia. An intracellular pool of compatible solutes of strain N1 was investigated by NMR spectroscopy. Cells grown in the presence of 5% NaCl at optimal growth temperature (28 °C) accumulated ectoine, glutamate, N(4)-acetyl-l-2,4-diaminobutyrate (NADA), alanine, trehalose, hydroxyectoine, and valine. Such a combination of compatible solutes is unique and distinguishes the strain from C. salexigens DSM 3043T. Hyperosmotic stress induced by 15% NaCl caused the accumulation of ectoine, NADA, and hydroxyectoine but led to a decrease in the amount of alanine, valine, and trehalose. The intracellular pool of glutamate was not significantly changed. A reduction of the growth temperature from 28 to 5 °C led to an increase in the amount of ectoine, NADA, trehalose, and hydroxyectoine. Ectoine was the major compatible solute.