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The number of aerobic mesophilic bacteria in milk is one of the indicators of the hygienic quality of milk. The aim of this work was to determine such aerobic mesophilic bacteria and their number in raw unpreserved milk and milk preserved with sodium azide. In 40 collected samples, the total number of aerobic mesophilic bacteria was determined using the classical method of counting colonies on a nutrient medium according to the international standard HRN EN ISO 4833-1:2013. The results showed a trend of decreasing the number of grown colonies in milk preserved with sodium azide. MALDI-TOF mass spectrometry also successfully identified 392 bacterial colonies in raw unpreserved milk samples and 330 colonies in preserved milk samples. Of these, 30 genera and 54 bacterial species were identified in the raw unpreserved milk samples, while 27 genera and 41 bacterial species were identified in the preserved samples. By using a collective approach, the present study provided a more detailed insight into milk’s hygienic quality and the presence of certain species before and after the preservation with sodium azide.

Geomicrobiologies of the hot springs of Chumathang and Panamik (located in the Indus and Nubra valleys of eastern and northern Ladakh, respectively) were revealed and compared with the Lotus Pond spring of Puga Valley (eastern Ladakh), which is known for its mineralogical and ecological peculiarities. Physicochemically, the vent-waters of the explored springs, Chumathang_01, Panamik_01 and Panamik_02, were distinct from Lotus Pond, with wide variations in boron, chloride, lithium, magnesium and potassium concentrations. Their microbiomes encompassed several unique constituents, but resembled Lotus Pond in being highly diversified and bacterial-mesophiles-dominated. Higher diversities of thermophilic archaea were detected in Chumathang_01 compared to Panamik_01 or Panamik_02. Statistical analysis of the geochemical and microbiological data highlighted the overall uniqueness of Lotus Pond, the constraint imposed by high temperature on the diversity of most bacterial groups, and the potential role of in-situ geochemicals in helping mesophilic bacteria inhabit the high-temperature environments. While the microbiome architecture of the 86°C Chumathang_01 (having the highest bacterial species count) closely resembled that of the geochemically similar 78°C Panamik_01, both the biomes were apparently shaped by temperature and pH. In contrast, the distinctive geochemistry of the 81°C Lotus Pond was apparently instrumental in sustaining a microbiome similar to that of the cooler (70°C) Panamik_02.

The physico-chemical properties of potato tubers change with age, which can affect not only the quality of the tubers but also the quality and shelf-life of fresh-cut potatoes (FCP) produced from older tubers. One of the methods that has proven useful for extending the shelf-life of some foods is ultraviolet-C (UV-C) irradiation. This study investigated whether UV-C irradiation can mitigate the negative effects of tuber age. FCP from tubers after storage (1 and 9 months), vacuum-packaged, were irradiated with UV-C (2.70 kJ m−2) and stored (6 °C/15 days). The total aerobic mesophilic bacteria count (TAMBC), total and soluble solids content, pH, firmness, color, chlorogenic acid, reducing sugars, sensory properties of raw FCP and subsequently boiled and fried FCP, and acrylamide content in fried FCP were monitored. UV-C irradiation of FCP does not affect all parameters equally for both tuber ages, but was generally effective in reducing TAMBC, and UV-C-treated samples reached a shelf-life of 15 days. UV-C irradiation improved the sensory properties of raw and thermally processed FCP at both ages. UV-C irradiation caused an increase in acrylamide content in fried FCP, regardless of. the tubers age, but all samples were safe in this respect.

Geomicrobiology of sulfur–boron-dominated, neutral-pH hydrothermal systems was revealed in a Trans-Himalayan spring named Lotus Pond, located at 4436 m, in Puga Valley, Ladakh (India), where water boils at 85°C. Water sampled along Lotus Pond’s outflow (vent to an adjacent river called Rulang), representing an 85–14°C gradient, had high microbial diversity and boron/chloride/sodium/sulfate/thiosulfate concentration; potassium/silicon/sulfide/sulfite was moderately abundant, whereas cesium/lithium small but definite. Majority of the bacterial genera identified in the 85–72°C samples have no laboratory-growth reported at >45°C, and some of those mesophiles were culturable. Sulfur-species concentration and isotope-ratio along the hydrothermal gradient, together with the distribution of genera having sulfur-oxidizing members, indicated chemolithotrophic activities in the 85–72°C sites. While biodiversity increased in the vent-to-river trajectory all-day, maximum rise was invariably between the vent (85–81°C) and the 78–72°C site; below 72°C, diversity increased gradually. Biodiversity of the vent-water exhibited diurnal fluxes relatable to the sub-surface-processes-driven temporal fluxes in physicochemical properties of the discharge. Snow-melts infiltrating (via tectonic faults) the ~160°C geothermal reservoir located within the breccia, at ~450 m depth, apparently transport mesophilic microbes into the thermal waters. As these micro-organisms emanate with the vent-water, some remain alive, illustrating that natural bacterial populations are more heat-resilient than their laboratory counterparts.

Antimicrobial compounds used as post-harvest treatment of fruit and vegetables can extend their shelf life by reducing the rate of microbial growth. Essential oils extracted from herbs or spices can also enhance shelf life due to their antimicrobial nature. Tomatoes harvested at consumption maturity were treated by spraying with aqueous solutions of basil essential oil (BEO) and glycerol in different concentrations (50, 100, 150, 200, 250 and 300 ppm) and stored by refrigeration at 8 ∘C and 85% relative humidity. The BEO used was obtained by extraction from indigenous crops of Ocimum basilicum and was analyzed by GC-MS for discerning of the constituents present in it. The main components identified in BEO were: eucalyptol, linalool, estragol, eugenol methyl-cinamate, trans-α-bergamotene, germacrene D, γ-cadinene and T-cadinol. During storage, in order to highlight the effect of the applied treatment, the following were determined: dry matter (DM), total soluble content (TSS), total phenols content (TP), antioxidant activity (AOA), color, weight loss and total number of aerobic mesophilic bacteria (AMB) during storage. It has been shown that spraying the fruit with solutions of different concentrations of BEO has significant effects on weight loss, DM, TSS, TP, AOA, color and TAMB, during storage. The lowest TP value was found in the control and the variant treated only with 2.5% aqueous glycerol solution (52.18 mg/100 g fw GAE) and the highest value in the variants treated with concentrations of 200, 250 and 300 ppm BEO (54.37, 55.00 and 57.81 mg GAE/100 g fw). The highest AOA values were found in the 300 ppm BEO-treated variant (119.23 μmol TE/100 g fw). Spraying tomatoes with aqueous solutions of glycerol 2.5% and BEO at a dose of 250 ppm prolongs their storage while maintaining their quality for fresh consumption.

While decomposition of organic matter by bacteria plays a major role in nutrient cycling in terrestrial ecosystems, the significance of viruses remains poorly understood. Here we combined metagenomics and metatranscriptomics with temporal sampling to study the significance of mesophilic and thermophilic bacteria and their viruses on nutrient cycling during industrial-scale hyperthermophilic composting (HTC). Our results show that virus-bacteria density dynamics and activity are tightly coupled, where viruses specific to mesophilic and thermophilic bacteria track their host densities, triggering microbial community succession via top-down control during HTC. Moreover, viruses specific to mesophilic bacteria encoded and expressed several auxiliary metabolic genes (AMGs) linked to carbon cycling, impacting nutrient turnover alongside bacteria. Nutrient turnover correlated positively with virus–host ratio, indicative of a positive relationship between ecosystem functioning, viral abundances, and viral activity. These effects were predominantly driven by DNA viruses as most detected RNA viruses were associated with eukaryotes and not associated with nutrient cycling during the thermophilic phase of composting. Our findings suggest that DNA viruses could drive nutrient cycling during HTC by recycling bacterial biomass through cell lysis and by expressing key AMGs. Viruses could hence potentially be used as indicators of microbial ecosystem functioning to optimize productivity of biotechnological and agricultural systems.

Temperature-induced cell death is thought to be due to protein denaturation, but the determinants of thermal sensitivity of proteomes remain largely uncharacterized. We developed a structural proteomic strategy to measure protein thermostability on a proteome-wide scale and with domain-level resolution. We applied it to , , , and human cells, yielding thermostability data for more than 8000 proteins. Our results (i) indicate that temperature-induced cellular collapse is due to the loss of a subset of proteins with key functions, (ii) shed light on the evolutionary conservation of protein and domain stability, and (iii) suggest that natively disordered proteins in a cell are less prevalent than predicted and (iv) that highly expressed proteins are stable because they are designed to tolerate translational errors that would lead to the accumulation of toxic misfolded species.

Summary Polyethylene terephthalate (PET) is a mass‐produced synthetic polyester contributing remarkably to the accumulation of solid plastics waste and plastics pollution in the natural environments. Recently, bioremediation of plastics waste using engineered enzymes has emerged as an eco‐friendly alternative approach for the future plastic circular economy. Here we genetically engineered a thermophilic anaerobic bacterium, Clostridium thermocellum, to enable the secretory expression of a thermophilic cutinase (LCC), which was originally isolated from a plant compost metagenome and can degrade PET at up to 70°C. This engineered whole‐cell biocatalyst allowed a simultaneous high‐level expression of LCC and conspicuous degradation of commercial PET films at 60°C. After 14 days incubation of a batch culture, more than 60% of the initial mass of a PET film (approximately 50 mg) was converted into soluble monomer feedstocks, indicating a markedly higher degradation performance than previously reported whole‐cell‐based PET biodegradation systems using mesophilic bacteria or microalgae. Our findings provide clear evidence that, compared to mesophilic species, thermophilic microbes are a more promising synthetic microbial chassis for developing future biodegradation processes of PET waste. Promising bioremediation strategies for plastics waste are of great importance and requirements. In our study, we constructed a recombinant Clostridium thermocellum strain expressing a secretory cutinase (LCC) as a thermophilic whole‐cell biocatalyst to degrade PET under high‐temperature condition (60°C). To our knowledge, this biocatalysis system demonstrates the highest PET degradation efficiency compared to reported whole‐cell‐based systems and also enjoys a low‐cost advantage over the free enzyme‐based process.

CRISPR-Cas9 is a powerful technology that has enabled genome editing in a wide range of species. However, the currently developed Cas9 homologs all originate from mesophilic bacteria, making them susceptible to degradation and unsuitable for applications requiring cleavage at elevated temperatures. Here, we show that the Cas9 protein from the thermophilic bacterium Geobacillus stearothermophilus (GeoCas9) catalyzes RNA-guided DNA cleavage at elevated temperatures. GeoCas9 is active at temperatures up to 70 °C, compared to 45 °C for Streptococcus pyogenes Cas9 (SpyCas9), which expands the temperature range for CRISPR-Cas9 applications. We also found that GeoCas9 is an effective tool for editing mammalian genomes when delivered as a ribonucleoprotein (RNP) complex. Together with an increased lifetime in human plasma, the thermostable GeoCas9 provides the foundation for improved RNP delivery in vivo and expands the temperature range of CRISPR-Cas9. While current CRISPR-Cas9 tools have revolutionized genome editing, they are not suitable for applications at elevated temperatures. Here, the authors characterize GeoCas9 from Geobacillus stearothermophilus , which is active up to 70°C and is stable in human plasma.

Edible insects are increasingly being considered as food and feed ingredients because of their rich nutrient content. Already, edible insect farming has taken-off in Africa, but quality and safety concerns call for simple, actionable hazard control mechanisms. We examined the effects of traditional processing techniques—boiling, toasting, solar-drying, oven-drying, boiling + oven-drying, boiling + solar-drying, toasting + oven-drying, toasting + solar-drying—on the proximate composition and microbiological quality of adult Acheta domesticus and Ruspolia differens, the prepupae of Hermetia illucens and 5th instar larvae of Spodoptera littoralis. Boiling, toasting, and drying decreased the dry matter crude fat by 0.8–51% in the order: toasting > boiling > oven-drying > solar-drying, whereas the protein contents increased by 1.2–22% following the same order. Boiling and toasting decreased aerobic mesophilic bacterial populations, lowered Staphylococcus aureus, and eliminated the yeasts and moulds, Lac+ enteric bacteria, and Salmonella. Oven-drying alone marginally lowered bacterial populations as well as yeast and moulds, whereas solar-drying alone had no effect on these parameters. Oven-drying of the boiled or toasted products increased the aerobic mesophilic bacteria counts but the products remained negative on Lac+ enteric bacteria and Salmonella. Traditional processing improves microbial safety but alters the nutritional value. Species- and treatment-specific patterns exist.