Caloramator mitchellensis sp. nov., a thermoanaerobe isolated from the geothermal waters of the Great Artesian Basin of Australia, and emended description of the genus Caloramator

The enhancement of energy supply in syngas-fermenting microorganisms

After the second industrial revolution, social productivity developed rapidly, and the use of fossil fuels such as coal, oil, and natural gas increased greatly in industrial production. The burning of these fossil fuels releases large amounts of greenhouse gases such as CO2, which has caused greenhouse effects and global warming. This has endangered the planet's ecological balance and brought many species, including animals and plants, to the brink of extinction. Thus, it is crucial to address this problem urgently. One potential solution is the use of syngas fermentation with microbial cell factories. This process can produce chemicals beneficial to humans, such as ethanol as a fuel while consuming large quantities of harmful gases, CO and CO2. However, syngas-fermenting microorganisms often face a metabolic energy deficit, resulting in slow cell growth, metabolic disorders, and low product yields. This problem limits the large-scale industrial application of engineered microorganisms. Therefore, it is imperative to address the energy barriers of these microorganisms. This paper provides an overview of the current research progress in addressing energy barriers in bacteria, including the efficient capture of external energy and the regulation of internal energy metabolic flow. Capturing external energy involves summarizing studies on overexpressing natural photosystems and constructing semiartificial photosynthesis systems using photocatalysts. The regulation of internal energy metabolic flows involves two parts: regulating enzymes and metabolic pathways. Finally, the article discusses current challenges and future perspectives, with a focus on achieving both sustainability and profitability in an economical and energy-efficient manner. These advancements can provide a necessary force for the large-scale industrial application of syngas fermentation microbial cell factories.

Effect of Caproicibacterium lactatifermentans inoculation on the microbial succession and flavor formation of pit mud used in Chinese Baijiu fermentation

Caproicibacterium lactatifermentans is a major caproate-producing bacterium in high-quality pit mud and has an impact on the synthesis of fatty acids during Baijiu fermentation. To develop an effective method for cultivating high-quality pit mud, we explored the role of Caproicibacterium lactatifermentans inoculation. The inoculation resulted in a high level of Caproicibacterium lactatifermentans (29.16%) and fortified pit mud produced abundant fatty acids and ethyl esters in short-term usage. Rare microbes, such as Hazenella coriacea, promoted the production of fatty acids. After long-term usage, changes in physicochemical properties led to a decrease in caproate-producing bacterium, namely Clostridium and Caproicibacterium, and an increase in microbes with limited fatty acid biosynthesis capability, including Proteiniphilum, Fastidiosipila, and Caldicoprobacter. These alterations ultimately led to a decrease in fatty acids and ethyl esters. In summary, Caproicibacterium lactatifermentans inoculation exhibited positive outcomes in obtaining high-quality pit mud. However, the maintenance of functional microbes necessitates further investigation.

Reduction of Vanadium(V) by Iron(II)-Bearing Minerals

Fe(II)-bearing minerals (magnetite, siderite, green rust, etc.) are common products of microbial Fe(III) reduction, and they provide a reservoir of reducing capacity in many subsurface environments that may contribute to the reduction of redox active elements such as vanadium; which can exist as V(V), V(IV), and V(III) under conditions typical of near-surface aquatic and terrestrial environments. To better understand the redox behavior of V under ferrugenic/sulfidogenic conditions, we examined the interactions of V(V) (1 mM) in aqueous suspensions containing 50 mM Fe(II) as magnetite, siderite, vivianite, green rust, or mackinawite, using X-ray absorption spectroscopy at the V K-edge to determine the valence state of V. Two additional systems of increased complexity were also examined, containing either 60 mM Fe(II) as biogenic green rust (BioGR) or 40 mM Fe(II) as a mixture of biogenic siderite, mackinawite, and magnetite (BioSMM). Within 48 h, total solution-phase V concentrations decreased to <20 µM in all but the vivianite and the biogenic BiSMM systems; however, >99.5% of V was removed from solution in the BioSMM and vivianite systems within 7 and 20 months, respectively. The most rapid reduction was observed in the mackinawite system, where V(V) was reduced to V(III) within 48 h. Complete reduction of V(V) to V(III) occurred within 4 months in the green rust system, 7 months in the siderite system, and 20 months in the BioGR system. Vanadium(V) was only partially reduced in the magnetite, vivianite, and BioSMM systems, where within 7 months the average V valence state stabilized at 3.7, 3.7, and 3.4, respectively. The reduction of V(V) in soils and sediments has been largely attributed to microbial activity, presumably involving direct enzymatic reduction of V(V); however the reduction of V(V) by Fe(II)-bearing minerals suggests that abiotic or coupled biotic–abiotic processes may also play a critical role in V redox chemistry, and thus need to be considered in modeling the global biogeochemical cycling of V.

Colombian Andean thermal springs: reservoir of thermophilic anaerobic bacteria producing hydrolytic enzymes

Anaerobic cultivable microbial communities in thermal springs producing hydrolytic enzymes were studied. Thermal water samples from seven thermal springs located in the Andean volcanic belt, in the eastern and central mountain ranges of the Colombian Andes were used as inocula for the growth and isolation of thermophilic microorganisms using substrates such as starch, gelatin, xylan, cellulose, Tween 80, olive oil, peptone and casamino acids. These springs differed in temperature (50-70 °C) and pH (6.5-7.5). The predominant ion in eastern mountain range thermal springs was sulphate, whereas that in central mountain range springs was bicarbonate. A total of 40 anaerobic thermophilic bacterial strains that belonged to the genera Thermoanaerobacter, Caloramator, Anoxybacillus, Caloranaerobacter, Desulfomicrobium, Geotoga, Hydrogenophilus, Desulfacinum and Thermoanaerobacterium were isolated. To investigate the metabolic potential of these isolates, selected strains were analysed for enzymatic activities to identify strains than can produce hydrolytic enzymes. We demonstrated that these thermal springs contained diverse microbial populations of anaerobic thermophilic comprising different metabolic groups of bacteria including strains belonging to the genera Thermoanaerobacter, Caloramator, Anoxybacillus, Caloranaerobacter, Desulfomicrobium, Geotoga, Hydrogenophilus, Desulfacinum and Thermoanaerobacterium with amylases, proteases, lipases, esterases, xylanases and pectinases; therefore, the strains represent a promising source of enzymes with biotechnological potential.

Complete Genome Sequence of Caloramator sp. Strain E03, a Novel Ethanologenic, Thermophilic, Obligately Anaerobic Bacterium

Here, we report the complete genome sequence of Caloramator sp. strain E03, an anaerobic thermophile that was isolated from a hot spring within the Rabbit Creek area of Yellowstone National Park. The assembly contains a single 2,984,770-bp contig with a G+C content of 31.3% and is predicted to encode 2,678 proteins.

Draft Genome Sequence of Cellulosilyticum sp. I15G10I2, a Novel Bacterium Isolated from a Coal Seam Gas Water Treatment Pond

Cellulosilyticum sp. strain I15G10I2 was isolated from a coal seam gas water treatment pond at the Spring Gully water treatment facility, Roma, Queensland, Australia. Analysis of the genome of 4,489,861 bp and G+C content of 35.23% revealed that strain I15G10I2 shared limited similarity to members of the genus Cellulosilyticum, family Lachnospiraceae.

Draft Genome Sequence of Caloramator mitchellensis, a Thermoanaerobe Isolated from the Waters of the Great Artesian Basin

The genome sequence of Caloramator mitchellensis strain VF08, a rod-shaped, heterotrophic, strictly anaerobic bacterium isolated from the free-flowing waters of a Great Artesian Basin (GAB) bore well located in Mitchell, an outback Queensland town in Australia, is reported here. The analysis of the 2.42-Mb genome sequence indicates that the attributes of the genome are consistent with its physiological and phenotypic traits.

Caloramator quimbayensis sp. nov., an anaerobic, moderately thermophilic bacterium isolated from a terrestrial hot spring

An anaerobic, moderately thermophilic, terminal-spore-forming bacterium, designated strain USBA AT, was isolated from a terrestrial hot spring located at an altitude of 2683 m in the Andean region of Colombia (04° 50′ 14.0″ N 75° 32′ 53.4″ W). Cells of strain USBA AT were Gram-stain-positive, straight to slightly curved rods (0.9×2.5 µm), that were arranged singly or in pairs, and were motile by means of flagella. Growth occurred at 37–55 °C and pH 6.0–8.0, with a doubling time of 2 h under the optimal conditions (50 °C and pH 7.0). Glucose fermentation in strain USBA AT required yeast extract or peptone (each at 0.2 %, w/v). The novel strain fermented sugars, amino acids, Casamino acids, propanol, propionate, starch and dextrin, but no growth was observed on galactose, lactose, xylose, histidine, serine, threonine, benzoate, butyrate, lactate, pyruvate, succinate, methanol, ethanol, glycerol, casein, gelatin or xylan. The end products of glucose fermentation were formate, acetate, ethanol and lactate. Strain USBA AT did not grow autotrophically (with CO2 as carbon source and H2 as electron donor) and did not reduce thiosulfate, sulfate, elemental sulfur, sulfite, vanadium (V) or Fe (III) citrate. Growth of strain USBA AT was inhibited by ampicillin, chloramphenicol, kanamycin, penicillin and streptomycin (each at 10 µg ml−1). The predominant fatty acids were iso-C15 : 0, C16 : 0 and iso-C17 : 0 and the genomic DNA G+C content was 32.6 mol%. 16S rRNA gene sequence analysis indicated that strain USBA AT belonged in the phylum Firmicutes and that its closest relative was Caloramator viterbiensis JW/MS-VS5T (95.0 % sequence similarity). A DNA–DNA relatedness value of only 30 % was recorded in hybridization experiments between strain USBA AT and Caloramator viterbiensis DSM 13723T. Based on the phenotypic, chemotaxonomic and phylogenetic evidence and the results of the DNA–DNA hybridization experiments, strain USBA AT represents a novel species of the genus Caloramator , for which the name Caloramator quimbayensis sp. nov. is proposed. The type strain is USBA AT ( = CMPUJ U833T  = DSM 22093T).

Draft genome sequence of Caloramator australicus strain RC3T, a thermoanaerobe from the Great Artesian Basin of Australia

Caloramator australicus strain RC3(T) (JCM 15081(T) = KCTC 5601(T)) is the type strain of a newly identified thermophilic species, which was isolated from red microbial mats that thrive at 66°C in the runoff channel of a Great Artesian Basin bore (New Lorne bore, registered number 17263) in outback Queensland, Australia. The ability of the C. australicus strain to use metals as terminal electron acceptors has led to concerns that it could colonize and enhance corrosion of the metal casing of Great Artesian Basin bore well pipes and that this could subsequently lead to bore failure and loss of water availability for the community which is so reliant on it. The genome of the C. australicus strain has been sequenced, and annotation of the ~2.65-Mb sequence indicates that the attributes are consistent with physiological and phenotypic traits.