Yeasts of the genus Rhodotorula have pink, orange, and red colors, indicating their ability to synthesize carotenoids. Due to their biological properties, carotenoids are widely used in the phytomedicine, chemical, pharmaceutical, cosmetic, food, and feed industries. One of the most important carotenoids is β-carotene, which exhibits interesting biological activities, such as antioxidant, anticancer, and antimicrobial. Rhodotorula yeasts were isolated from the natural environment and analyzed using morphological and molecular methods. Species were identified based on the restriction fragment length polymorphism analysis and sequencing of the rDNA internal transcribed spacer region (ITS). In this work, the β-carotene content of Rhodotorula yeasts was investigated when grown on a solid YEPD medium at different temperatures (4 °C and 26 °C) using various light intensities (8-10 µmol/m²s). The biomass was collected, and carotenoids were extracted using dimethylformamide (DMF). The amount of β-carotene was calculated based on absorption at 440 nm. The highest β-carotene contents were found in R. babjevae, R. glutinis, R. graminis, and R. kratovchilovae after 14 days of incubation at 26 °C in the dark. The level of β-carotene was 30 to 55% lower depending on the yeast species when the yeast culture after 2 days of cultivation at 26 °C was transferred to 4 °C, followed by 12 days of incubation in the dark. When yeasts were kept in the light at 4 °C, out of the eight yeast species tested, R. mucilaginosa and R. babjevae accumulated about 20-30% more β-carotene than under dark conditions. Our results show that yeasts that are cultured in the dark at 26 °C accumulate β-carotene better than yeasts that are held under the same conditions in the light. The synthesis and accumulation of β-carotene are decreased at a low temperature. The obtained data suggest that isolated Rhodotorula yeast species can be promising for carotenoid production under appropriate conditions.

Bacterial antibiotic resistance (AR) has become a critical global health threat. AR is mainly driven by adaptive resistance mutations and the horizontal gene transfer of resistance genes, both of which are enhanced by genome recombination. We have previously discovered that genome recombination-mediated tRNA up-regulation is important for AR especially in the early stages. RecA is the most important genome recombination factor. Therefore, RecA inhibitors should be effective in reducing AR. In this study, we found that BRITE338733 (BR), a RecA inhibitor, can prevent ciprofloxacin (CIP) resistance in subculturing Escherichia coli strain BW25113 in the early stages (up to the 7^th generation). In the presence of BR, the tRNA was decreased, so the bacteria cannot evolve resistance via the tRNA up-regulation-mediated AR mechanism. The RecA expression level was also not increased when treated with BR. Transcriptome sequencing revealed that BR causes a down-regulation of ATPase activity and therefore suppresses the energy state of bacteria. Also, the effective concentrations of BR do not harm human cell viability, indicating its clinical safety. These findings demonstrate that BR effectively delays the emergence of spontaneous antibiotic resistance by targeting RecA-mediated pathways. Our findings shed light on a new strategy to counteract the clinical AR: applying BR with the antibiotics together at the beginning.

Metabolite analysis is a promising method and is increasingly being used to identify dysfunctions of various organs in patients. One of the sources of metabolites in the body is the gut microbiota. An increase in sepsis-associated aromatic microbial metabolites is a prognostically unfavorable factor and increases the risk of death in patients with sepsis.

The aim of this work was to evaluate the composition and function of the gut microbiota in patients with sepsis compared to healthy donors using chromatograph mass spectrometry.

The study included 10 patients with sepsis and 9 healthy donors, comparable in gender and age. The incubation of feces samples was carried out in thioglycollate medium (TG (at 37 ℃)) with the addition of sepsis-associated microbial metabolites (25 μM phenyllactic acid (PLA) or 25 μM 4-hydroxyphenyllactic acid (4-HPLA)). Metabolite concentrations were determined using a GC-2010 Plus gas chromatograph and a GCMS-QP2020 mass spectrometer (Shimadzu, Japan). The proportion of sepsis-associated aromatic metabolites in patients with sepsis was significantly higher than normal with a significance of 40%, while in donors, it did not exceed 5%. Comparison of the metabolomic profiles of normobiota and pathobiota in an experiment showed that when loaded with sepsis-associated metabolites of PLA and 4-HPLA, the microbiota of a healthy subject biotransforms them into the end products of microbial metabolism, whereas the pathobiota of a septic patient is unable to perform this function. Thus, in sepsis, the normobiome is transformed into a pathobiome, which reflects the dysfunction of the gut microbiota.

Listeria monocytogenes is one of the most important bacterial foodborne pathogens. The ability to survive in diverse environmental conditions and the capacity to form biofilms are critical to guaranteeing food safety. No current data are available regarding the detection of this microorganism in fresh pork meat in the region. The aim of this study was to determine the presence of L. monocytogenes in fresh pork meat from meat retailers in La Plata, Buenos Aires, Argentina.

The present study is part of a food safety observational, transversal, and descriptive research project. From August to November 2024, a total of 138 pork meat samples were collected from 46 local meat retailers selected randomly in the city of La Plata. In each one of the stores, three samples were pooled to form a unique sample. Each pool of 25 g was cultured in 225 ml of Half Fraser broth for 24 h at 30 °C. After the pre-enrichment step, 0.1 ml of each culture was subcultured in 10 ml of secondary enrichment medium (Fraser) supplemented with 0.1 ml of ferric ammonium citrate for 48 h at 37 °C. Plating out and identification was performed with CHROMagar™ for Listeria according to the manufacturer’s instructions. Suspected L. monocytogenes were selected for biochemical identification according to ISO 11290-1, and those confirmed were subcultured and preserved at −20 °C. Of the 46 retailers sampled, 32.61 % resulted positive for Listeria monocytogenes. Although this is the first report of Listeria monocytogenes in fresh pork meat in the region, similar values were reported from beef butcher shops.

The isolation of this microorganism, its survival characteristics, and the context of meat retailers that sell ready-to-eat food products might indicate the presence of other foodborne pathogens implicated in cross-contamination and food safety, highlighting the importance of implementing good manufacturing practices.

Staphylococcus aureus, including methicillin-resistant strains (MRSA), is a bacterium responsible for multiple types of human infections. The discrepancy between phenotypic and genotypic resistance is called silencing of antibiotic resistance by mutation (SARM), while the genes are called silent or cryptic. The presence of SARM bacteria carries a risk of implementing an ineffective antimicrobial drug in therapy, as the gene would not be activated until therapy. This study aimed to determine the frequency of SARM and its genetic mechanisms. The virulence and sequence type of the SARM strains were also characterized.

In total, 334 S. aureus strains were investigated for phenotypic resistance to cefoxitin, erythromycin, tetracycline, gentamycin, and mupirocin. PCR was used to screen for the presence of corresponding antibiotic-resistance genes. SARM isolates were further characterized by the detection of genes encoding toxins, adhesins, types of SCCmec cassette, and genotyping with MLST. Silenced genes were sequenced to determine the genetic defect and its consequences for protein translation.

The analysis showed the presence of SARM in 0.6% of S. aureus strains (2/334). In both cases, they were strains harbouring the mupA gene (resistance to mupirocin). Sequencing showed the presence of a deletion, resulting in the incorrect translation of the nucleotide into an amino acid sequence, shortening the amino acid chain and inhibiting the synthesis of the protein responsible for mupirocin resistance.

Mupirocin is an antibiotic applied in the treatment of staphylococcal infection of the skin, including the eradication (the removal of a microorganism from the body) of S. aureus from the nasal cavity. Despite the fact that the analysis showed a low share of SARM (<1%), there is still a risk of antimicrobial therapy failure and reinfection. Further studies should also focus on determining factors that increase the probability of activation of silent genes responsible for resistance to mupirocin.

The riparian plant Salvia procurrens Benth (commonly named blue creeper) is a native species from South America that is commonly used to remediate degraded lands, and in particular, to stabilize riverbanks due to its environmental adaptation. This study proposes co-inoculating this plant species with two plant growth-promoting microorganisms, Azospirillum brasilense SP7 and Bacillus subtilis subsp. spizizenii, to enhance restoration effects on riversides. Single-node blue creeper cuttings were placed in forestry plug trays to produce rooting using sand as a substrate. After 20 days, the plants were transplanted into 3L pots and inoculated with the bacterial mixture, applying 5 mL of inoculum at the base of each plant's stem. After six months, the plants were harvest and the following parameters were evaluated: plant height, root length, number of leaves and nodes, shoot and root biomass, and above- and belowground heavy metal concentrations. In the bioinoculant, the number of B. subtilis spores was quantified, reaching 1.6 × 10⁵ CFU mL⁻¹. Bacterial inoculation had positive effects, increasing plant height (37%), root length (8%), and the number of leaves (57%) with respect to the control, but it had no effect on the number of nodes. Shoot and root dry weight in the inoculated plants more than doubled compared to the control, increasing by 117% and 167%, respectively. The roots of the inoculated plants showed higher contents of Fe, Cu, Mn, Cd, and Pb than those of the control plant. In particular, root Pb levels were more than 100% higher in the inoculated plants than in the non-inoculated plants. Co-inoculation was proven to have a beneficial effect not only in enhancing the growth of S. procurrens, making it ideal as ground cover in revegetation programs for riparian areas, but also for its capacity to accumulate metals.

Biofilms represent a key survival strategy, providing bacteria with effective protection against abiotic and biotic stress. In the laboratory, Bacillus subtilis subsp. spizizenii forms a biofilm at the liquid–air interface, the matrix of which is primarily composed of polysaccharides, proteins, and nucleic acids. The aims of this study are as follows: 1) to evaluate how the chemical composition of the matrix and the stability of the biofilm are modified when the bacteria grow using either glucose or glycerol as carbon sources; 2) to study the effect of temperature on biofilm production and planktonic growth. The bacteria were cultured in a saline medium with 55 mM L-glutamic acid and 1% glucose or glycerol at different temperatures. Biofilm was produced under static conditions and planktonic cells by shaking at 150 rpm. Biofilms were analyzed by high-resolution chromatography. In the presence of glucose, polysaccharide monomers at the biofilm matrix showed substitutions that conferred acidic properties. This biofilm disintegrated after 5 days at 20 °C and 15 days at 4 °C. In contrast, when cultured with glycerol, the polysaccharide sugars were neutral, and the biofilm disintegrated after 20 days at 20 °C and 60 days at 4 °C; visually, this biofilm was more compact. Planktonic growth of B. subtilis was highest at 45 °C, whereas the maximum biofilm formation (1.2 mg/mL of culture) was achieved between 30 °C and 37 °C. In the static cultures, the planktonic form of B. subtillis disappeared within 24 hours after biofilm synthesis. In conclusion, the biofilms obtained from different carbon sources show differences, suggesting that the substituents of the polysaccharide monomers might be crucial for their structural properties. Moreover, in cases where the biofilm was formed at the liquid–air interface, the planktonic cells developed in this culture migrated toward the biofilm and as a result, the medium appeared clear; this was likely due to to nutrient depletion, which does not support planktonic growth.

The purpose of this study was to investigate how replacing polyethylene row covers with other types of cover influences soil properties, microbial diversity, the composition of soil communities, and carbon metabolism in artichoke cropping. We carried out five treatments in four replicates, including plastic film, buckwheat, kurapia, crimson clover, and white clover. The samples were collected after rainfall events totalling 2 in. of precipitation during February 2024.

In the cross-sectional data, results were comparable between treatments with regards to physical and chemical properties, but there were significant differences in soil moisture and pH, with plastic having the lowest moisture and lowest pH. Higher CFUs in plastic at a 10^-4 dilution were noted.

For the composition and abundance of bacteria, the results indicated the following differences between white clover vs. plastic: higher Adhaeribacter sp. and Phycicoccus sp. abundance in white clover treatments; higher Rhodobacter sp. and Sphingobium sp. abundance in plastic treatments. The following differences were observed between the legume treatment vs. the control: Phycicoccus sp. and Stenotrophomonas sp. abundance was higher in the legume treatment. Results with low fold change values <1.33 were omitted.

The Chi-square test was negative for differences in proportions of carbon sources that could be metabolized in Biolog Ecoplate trials by each group (p=0.16). There was a gap in the mosaic plot between the proportion of carbon sources metabolized by white clover communities and other treatments. For the artichokes, the GLM logit model indicated a difference between white clover treatments when compared with other treatments (p=7.76*10^-5). The carbon sources that differed significantly in the microbes' ability to metabolize themwere delta-glucosaminic acid, L-alpha-glycerol phosphate, glucose-1-phosphate, i-erythritol, itaconic acid, phenylalanine, serine, and threonine.

Further studies should include microbial biomass analyses and nutrient analyses, and consider the effects of the treatments on yield. Longitudinal analysis of soil physical and chemical properties will confirm the effects of the treatments on physical and chemical properties of the soil.

Rhizosphere soil is one of the unique microbial habitats, especially the actinobacteria. This study was carried out to screen and isolate actinomycetes exhibiting antifungal activity. Initially, the soil samples collected from Allium ascalonicum L., Alpinia galangal, Amorphophallus sp., Clausena harmandiana, and Cymbopogon citratus were pretreated by air-drying and subsequent heat incubation. By using three different media (international Streptomyces project 1 and 2 (ISP-1 and ISP-2) and starch casein agar (SCA)), 79 isolates were obtained and identified as actinomycetes by morphology. Ten actinomycete isolates were then randomly selected to assess their antifungal activity against five pathogenic fungi: Aspergillus sp., Colletotrichum sp., C. acutatum, C. gloeosporioides, and Lasiodiplodia theobromae. Initial screening showed that there were three most active strains, namely CN1, CN4, and LG5, exhibiting a strong and broad spectrum. The bacterial culture supernatants were then prepared and evaluated for their stability under various pH and temperature conditions. The data obtained showed that the antifungal activity of the three culture supernatants was varied depending on the bacterial source and testing fungal strains. The present work implies that rhizospheric soil samples are an attractive source for the discovery of numerous actinomycetes with activity against phytopathogenic fungi. Identification of the bacterial species and determination of the active compounds are essential for further analysis for use in fungal control.

Loquat (Eriobotrya japonica) is economically important, but abiotic stresses like drought, salinity, and severe temperatures are having an increasing effect on its productivity. Plant cells experience oxidative stress, which leads to the buildup of reactive oxygen species (ROS). The production of antioxidant enzymes by specific bacteria in the loquat rhizosphere can reduce ROS levels and possibly increase the plant's resistance to these stresses. However, little is known about the processes by which these bacteria aid loquat in defending against oxidative stress. The purpose of this work is to identify and describe the bacterial strains linked to loquat that produce antioxidant enzymes and to clarify how they help loquat plants. After separating bacterial strains from the loquat rhizosphere, we examined their antioxidant enzyme activity, paying particular attention to the synthesis of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) under stress-like circumstances. To identify and examine the genes in charge of the synthesis of antioxidant enzymes and the control of stress responses, high-performing strains were chosen for in-depth characterization utilizing enzyme activity tests and molecular methods such as qPCR and genome sequencing. The chosen bacterial strains were administered to loquat seedlings, which were subsequently subjected to simulated oxidative stress, to evaluate their practical effects. To assess the effect on plant health, measurements were made of three important physiological indicators: electrolyte leakage, relative water content, and chlorophyll concentration. Furthermore, the amount of ROS in loquat tissues was measured, and qPCR was used to examine the expression of the plant's own antioxidant genes. This study found that antioxidant-producing bacteria improved loquat’s oxidative stress tolerance, lowering ROS levels, increasing chlorophyll, and reducing electrolyte leakage, thus boosting resilience to oxidative damage. These findings pave the way for sustainable microbial inoculants to reduce oxidative stress in loquat farming, enhancing crop stability under tough conditions.