Extremophiles最新文献

Uncultured microorganisms represent a significant portion of the biodiversity of Earth and play crucial roles in ecosystem functioning, particularly in extreme environments. Among these, a novel archaeal lineage, the "OYS group," was recently identified via 16S rRNA gene sequencing from actively boiling hot springs in northeastern Japan. This lineage forms a deep-branching clade, an early-diverging group that is phylogenetically distinct from all the known archaeal phyla. However, no additional reports of the OYS group have emerged from other geothermal environments, raising questions about its ecological niche and geographic distribution. In this study, we conducted a comprehensive 16S rRNA gene-based survey of 17 hot spring sites in Central Kyushu, Japan, covering a broad range of temperatures (30-95 °C) and pH values (4.1-8.8), to assess the distribution and environmental preferences of the OYS group archaea. The OYS group was detected at five high-temperature sites with relative abundances of up to 16.9% and was particularly dominant in the Tsuetate hot spring. Phylogenetic analyses confirmed that these sequences formed a monophyletic clade, a single origin group with the previously reported OYS group sequences. Multivariate analyses revealed co-occurrence with other thermophilic taxa, indicating a possible preference for high-temperature niches. These findings expand the known habitat range of the OYS group and highlight their potential ecological significance in geothermal ecosystems.

Polycyclic aromatic hydrocarbons (PAH) are prevalent environmental contaminants, which exhibit the mutagenic, carcinogenic, and teratogenic properties. The growing demand for efficient PAH biodegradation (BD), particularly in wastewater treatment. This research investigates hydrocarbon degradation using Vreelandella piezotolerant DM1 across a various pH levels (4, 6, 7, 8, and 10) and its enzymatic capabilities. The study assessed the degradation potential of anthracene and phenanthrene under varying PAH concentrations and pH conditions. Optimal bacterial growth and degradation were observed at 300 mg/L of both anthracene and phenanthrene at pH 8. To elucidate the degradation mechanisms, crucial intermediates were identified using gas chromatography mass-spectrometry (GC-MS). The hydrocarbon breakdown intermediates including anthracene-cis-1,2-dihydrodiol, (3Z)-4-[3-hydroxy(2-naphthyl)]-2-oxobut-3-enoic acid, 6,7-benzocoumarin, 1-hydroxy-2-naphthaldehyde, phenanthrene-cis-1,2-dihydrodiol, 1-hydroxy-2-naphthoic acid, and salicylic acid were observed during BD. Both intermediate compounds were conformed the salicylic acid pathway. GC-MS confirms the efficient degradation rates of 62% for anthracene, 82% for phenanthrene, and 83% for mixed hydrocarbons. These observations confirm that optimal conditions are obligatory for the enzymatic activity of the DM1 and a biodegradation pathway was proposed on the identified intermediates. In conculsion, V. piezotolerant DM1 serves as a potential candidate for hydrocarbon degradation in contaminated environment.

L-Asparaginase (L-ASNase) is a chemotherapy drug that has been used as a therapy for the treatment of some types of cancer, including leukemia and lymphoma. Its action involves inhibiting the growth of tumor cells by reducing the availability of asparagine in the body. L-ASNase is an enzyme produced by microorganisms; however, they have adverse effects, which may be related to the activities of glutaminase and urease. Bioprospecting in cold environments, such as the Antarctic continent, may be a promising alternative in the search for enzymes with differentiated properties. For these reasons, the present study evaluated the production of glutaminase- and urease-free L-asparaginase by fungi isolated from soil and wood collected on two islands of the South Shetland Archipelago, Antarctica. A total of 39 filamentous fungi were recovered. Mortierella turficola FM2.1, isolated from wood, produced only L-asparaginase in a solid culture medium assay, showing an enzymatic index of 2.83. The effects of enzymatic extracts on HBMEC, MRC-5, and MIAPaCa-2 cell lines were investigated. MTT assay showed IC₅₀ lower than that of the control, especially in the carcinogenic MIAPaCa-2 cell line. Fluorescence analysis of MIA PaCa-2 showed deformations in the cytoskeleton and nucleus of cells treated with enzymatic extracts up to 50%, in addition to a reduction in cell quantity. These results suggest that L-ASNase produced by the FM2.1 strain may have potential application in the treatment of pancreatic cancer. However, cytotoxic action has been observed in non-tumor cells. Future studies on the characterization of L-ASNase from enzymatic extracts for biotechnological applications should be conducted, aiming for trials with fewer side effects.

We previously demonstrated that the hyperthermophilic bacterium Thermotoga maritima has unique metabolic pathways for D- and L-amino acids. In the present study, we characterized O-acetyl-L-homoserine sulfhydrylase (MetY) TM0882 associated with L-methionine biosynthesis. MetY catalyzes the production of L-homocysteine from O-acetyl-L-homoserine and hydrogen sulfide. We found that TM0882 also possesses β-lyase, racemase/α-epimerase, aminotransferase, and decarboxylase activities. This enzyme displayed L-cysteine β-lyase activity as well as racemase/α-epimerase activity toward glutamate and threonine. Furthermore, TM0882 exhibited aminotransferase and L-aspartate 4-decarboxylase activities. Catalytic efficiency (k_cat/K_m) for β-lyase activity was highest among the four additional activities. TM0882 is therefore a multifunctional enzyme possessing four different activities in addition to sulfhydrylase activity.

Microbial communities inhabiting geothermal springs in the Republic of Dagestan, Russia, have not been studied by culture-independent methods. We have investigated the taxonomic composition, metabolic potential and rates of methane oxidation of microbial communities in two geothermal springs with methane emission (Artuzen and Miatli) located in Dagestan. Methane oxidation rates measured by the radiotracer technique varied from 3.7 to 96.5 nmol CH₄ cm^- 3 day^- 1. 16S rRNA gene amplicon sequencing indicates that in the Artuzen hot springs (54 °C), with a salinity of 2.5%, the primary production of organic matter is performed by mesophilic cyanobacteria, while in the freshwater Miatli hot springs (58 °C) primary producers are thermophilic cyanobacterium Thermosynechococcus and photosynthetic members of Chloroflexi. Analysis of metabolic capabilities of the metagenome assembled genomes in one of Artuzen samples shows that anaerobic bacteria belonging to Anaerolineae and Marinisomatota are the key decomposers of complex organic substances. The main terminal electron-accepting process in the sediment is acetoclastic methanogenesis carried out by the genus Methanocrinis. The presence of "Candidatus Methanospirareceae" (ANME-1) suggests the involvement of anaerobic archaea in methane oxidation. Thus, our study extends the current knowledge of the phylogenetic and metabolic diversity and activity of the prokaryotes inhabiting terrestrial hydrothermal environments.

High-altitude regions present various environmental challenges, yet the inhabitants living in these areas have adapted remarkably well, maintaining good health while living in close harmony with nature. A key factor contributing to this resilience is their dependency on dairy products as a primary part of their diet. These traditional dairy foods are rich in beneficial microbes with notable probiotic and enzymatic properties. Microbes from these products produce a variety of enzymes such as β-galactosidase, β-glucosidase, proteases, lipases, and pectinases. They exhibit high enzymatic activity and are in high demand in the food industry due to their effectiveness and acceptable nature. The growing need for stable, efficient enzymes with GRAS status and safe for consumption has fuelled interest in the exploration of dairy-derived microorganisms from high-altitude environments. These microbes, which are adapted to extreme and stressful conditions, exhibit strong enzymatic potential. Therefore, this review aims to highlight the emerging potential of high-altitude dairy microbes as a valuable resource for industrially significant enzymes, their potential applications in the food industry, and limitations and challenges of using high-altitude dairy-derived microbes.

This study explores the protective roles of three compatible solutes i.e. sucrose, trehalose, and proline, against temperature-induced cellular damages in the thermophilic cyanobacterium Mastigocladus sp. TA-8. The organism was exposed to sub-optimal (25 °C) and supra-optimal (50 °C) temperatures from its optimal 45 °C, with and without solute supplementation. Morphological, physiological, biochemical, and transcript-level alterations were analyzed. The maximum growth inhibition was occurred at 25 °C, accompanied by elevated reactive oxygen species, malondialdehyde content and redox imbalance. Nitrogen metabolism was also significantly impaired at 25 °C and evidenced by reduced total nitrogen, decreased glutamine synthetase activity, and altered α-ketoglutarate levels. At 50 °C, photosynthetic efficiency was predominantly reduced where sucrose was more effective in providing protection, likely due to enhanced ROS scavenging and increased antioxidant enzyme activities, improved redox potential and reduced MDA levels. Contrastingly, proline and trehalose conferred huge protection at 25 °C. Additionally, proline also fulfilled the nitrogen requirement at lower temperature, evidenced by higher glutamate and total nitrogen level, along with the upregulation of proline catabolism gene p5cdh. Conclusively, findings suggested that the compatible solutes played a major contribution in the protection against oxidative damage induced by thermal stress and maintaining cellular redox balance in Mastigocladus sp. TA-8.

Bacterial metal recovery is regarded as an environmentally friendly alternative to chemical hydrometallurgical waste metal recycling. However, conventional studies are generally conducted under neutral pH conditions, even though typical acidic metal leachate is strongly acidic. Previously, we isolated the bacterial strain Priestia sp. Mn7, which can grow under neutral pH and recover metals (Co, Cu, Li, Mn, and Ni) under pH 1.5. This study aimed to clarify this strain's metal tolerance and recovery mechanisms under pH 1.5 conditions. Metal recovery test was conducted using pH 1.5 solution without the five metal species described above. Enhanced expression of genes related to the sugar ATP binding cassette transporter and increased sugar concentration in metal-abundant solution indicated that the strain expels sugar from the cell as a metal stress response under strongly acidic conditions. Dead cells did not recover metals except for Mn. Additionally, the recovered metals were distributed on the cell surface. These results indicated that the strain recovers tested metals via bioprecipitation related to sugar expulsion. To the best of our knowledge, this is the first study to elucidate the metal tolerance and recovery mechanisms of acid-tolerant bacteria under pH 1.5, further contributing to the understanding and utilization of acid-tolerant bacteria.