Physiological and genomic characterization of Methanothermobacter thermautotrophicus strain Z-73A, an isolate from deep underground.

ISOLATION AND CHARACTERIZATION OF A THERMOPHILIC BACTERIUM, GEOBACILLUS SP. STRAIN MAS2, FROM A HOT SPRING OF BALOCHISTAN, PAKISTAN

Till to date, there is no report on isolation of microorganisms from the Mahiwal hot water spring in Balochistan, Pakistan. In the current manuscript, we report on isolation and morphological, biochemical and molecular characterization of a thermophilic microorganism from this hot water spring. The isolated bacterial strain, MAS2, is rod shaped with 1 µm width and 5 µm length. It forms cream-colored slimy colonies. The strain has the ability to grow in the presence of air between 40 and 75 °C with an optimum growth temperature and pH of 65 °C and 6.5, respectively. It can utilize various sugars, hydrocarbons and carboxylic acids as sole carbon source. No additional salt is required for its growth, though relatively higher yield was achieved with the addition of 0.5% NaCl. The strain MAS2 is capable of producing several important extracellular enzymes of industrial use including an amylase, a lipase, an oxidase and a protease. The 16S rRNA gene sequence of strain MAS2 exhibited high homology with various species belonging to genus Geobacillus. The highest homology of 98.66% was observed with Geobacillus kaustophilus. However, the biochemical characteristics of the strain were more similar to Geobacillus thermopakistaniensis and Geobacillus uzenensis. These results indicate that strain MAS2 represents an unidentified species belonging to genus Geobacillus. Keywords: Thermophiles; 16S rRNA sequence: Geobacillus sp. MAS2; biochemical characterization; extracellular enzymes.

Harnessing a marine-derived Rhodococcus strain for cross-habitat bioaugmentation of malodorant skatole: Performance and ecological response.

Findings identify Rhodococcus sp.

A Novel n-Hexadecane-Degrading Bacterium Provisionally Named “Thermalkanevorax longiformis” Isolated from a Deep-Sea Hydrothermal Vent

Hydrothermal systems contain diverse alkanes derived from biological and geological processes, providing potential carbon and energy sources for microorganisms. However, cultivated thermophilic alkane-utilizing bacteria from hydrothermal environments remain poorly characterized. In this study, a strain L01 was isolated from a deep-sea hydrothermal vent and identified as an alkane-degrading bacterium. The strain L01 grew at 55 °C and pH 7.0 in medium supplemented with n-hexadecane under microoxic conditions. Cells were elongated rods approximately 10–20 μm long and ~0.2 μm wide. Phylogenetic analyses based on 16S rRNA gene sequence similarity (93.11% to the closest described relative), average amino acid identity (AAI, 66.27–66.58%), average nucleotide identity (ANI, 80.80–83.05%), and digital DNA-DNA hybridization (dDDH, 12.5–20.8%) demonstrated that strain L01 represents a previously unrecognized genus within the family Symbiobacteriaceae, for which the provisional name “Thermalkanevorax longiformis” is proposed. An isotope tracing experiment together with genomics and transcriptomics revealed coordinated physiological and metabolic responses associated with n-hexadecane utilization by strain L01. These findings provide a cultivated representative of the family Symbiobacteriaceae with physiological and metabolic responses to n-hexadecane, thereby providing a basis for further investigation of hydrocarbon metabolism.

Isolation of a Novel Brevibacillus parabrevis PS12 Strain from Soil and Determination of Optimal Conditions for Arginase Production

Among the 20 isolates, one isolate was identified as Brevibacillus parabrevis PS12, representing the first report from Iraqi soil, which contributed to an increase in bacterial biomass which led to a rise in the specific activity of arginase.

Production and Characterization of Poly(3-hydroxybutyrate) by Thermophilic Geobacillus sp. Strain SL28 Isolated from a Natural Hot Spring

Polyhydroxyalkanoates (PHAs) are biodegradable microbial polyesters that may reduce dependence on petroleum-derived plastics, but broader use remains constrained by production costs and tightly controlled cultivation. Thermophilic microorganisms have attracted increasing attention as promising PHA producers because they can be cultivated at elevated temperatures, reducing contamination risks and operational costs. In this study, a thermophilic Geobacillus sp. strain SL28 isolated from a Vietnamese hot spring was evaluated for its PHA-producing capability. Temperature, initial pH, carbon and nitrogen sources, C/N ratio, and cultivation time were examined. Intracellular inclusions were assessed by Sudan Black B and Nile Blue A staining and transmission electron microscopy, whereas the recovered polymer was characterized by FE-SEM, Fourier-transform infrared spectroscopy (FTIR), gas chromatography–mass spectrometry (GC–MS), 1H- and 13C-nuclear magnetic resonance (NMR) spectroscopy, capillary viscometry, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and tensile testing. Under the optimized cultivation conditions identified by one-factor experimentation (50 °C, pH 7.0, sucrose, peptone, C/N 25:1, and 72 h), SL28 reached a dry cell weight of 2.215 ± 0.16 g/L and a PHA concentration of 1.383 ± 0.04 g/L, equivalent to 62.57 ± 2.82% of DCW. Structural characterization confirmed that the recovered polymer was poly(3-hydroxybutyrate) (PHB). The purified PHB also exhibited favorable thermal stability, a relatively high molecular weight, and satisfactory mechanical properties. These results demonstrate the potential of thermophilic Geobacillus sp. SL28 as a promising candidate for PHB production.

Genomic and physiological characterization of newly isolated nitrous oxide-reducing bacterium Stutzerimonas frequens strain E49 from landfill leachate-treating activated sludge