Folia microbiologica最新文献

Yeasts are unicellular fungi that occur in a wide range of ecological niches, where they perform numerous functions. Furthermore, these microorganisms are used in industrial processes, food production, and bioremediation. Understanding the physiological and adaptive characteristics of yeasts is of great importance from ecological, biotechnological, and industrial perspectives. In this context, we evaluated the abilities to assimilate and ferment different carbon sources, to produce extracellular hydrolytic enzymes, and to tolerate salt stress, heavy metal stress, and UV-C radiation of two isolates of Eremothecium coryli, isolated from Momordica indica fruits. The two isolates were molecularly identified based on sequencing of the 18S-ITS1-5.8S-ITS2 region. Our isolates were able to assimilate nine carbon sources (dextrose, galactose, mannose, cellobiose, lactose, maltose, sucrose, melezitose, and pectin) and ferment three (glucose, maltose, and sucrose). The highest values of cellular dry weight were observed in the sugars maltose, sucrose, and melezitose. We observed the presence of hyphae and pseudohyphae in all assimilated carbon sources. The two isolates were also capable of producing amylase, catalase, pectinase, and proteases, with the highest values of enzymatic activity found in amylase. Furthermore, the two isolates were able to grow in media supplemented with copper, iron, manganese, nickel, and zinc and to tolerate saline stress in media supplemented with 5% NaCl. However, we observed a decrease in CFU at higher concentrations of these metals and NaCl. We also observed morphological changes in the presence of metals, which include changes in cell shape and cellular dimorphisms. The isolates were sensitive to UV-C radiation in the shortest exposure time (1 min). Our findings reinforce the importance of endophytic yeasts for biotechnological and industrial applications and also help to understand how these microorganisms respond to environmental variations caused by human activities.

Escherichia coli is a significant pathogen in extraintestinal infections, and ESBL-producing E. coli poses a major clinical challenge due to its antibiotic resistance. This study comprehensively analyzed E. coli isolates from urine and blood samples of patients with urinary tract and bloodstream infections at three major tertiary hospitals in South Korea. The goal was to provide insights into the distribution, antibiotic resistance, and virulence factors of these strains. Our analysis identified CTX-M and TEM as the dominant ESBL types, found in 71.7% and 61.7% of isolates, respectively, with 46.7% showing co-occurrence. Multilocus sequence typing (MLST) revealed the predominance of high-risk clones such as ST131, ST69, ST73, and ST95, with rare sequence types like ST410 and ST405 also identified. The high prevalence of virulence factors, including iutA (80.8%) and kpsMII (74.2%), further highlights the complexity of these strains. In addition, 38.3% of clinical isolates contained a combination of siderophore, adhesin, protectin, and toxin-related genes. There was no significant difference between urinary tract and bloodstream infections or regional differentiation in Korea. This study highlights the importance of controlling ESBL-producing E. coli infections, especially given the increasing incidence among patients with underlying medical conditions and older adults who are more susceptible to urinary tract infections. These findings serve as valuable indicators for pathogen analysis, especially those harboring antibiotic resistance and toxin genes. The insights gained are expected to contribute significantly to the development of infectious disease prevention and control strategies.

The isolation and study of fungi within specific contexts yield valuable insights into the intricate relationships between fungi and ecosystems. Unlike culture-independent approaches, cultivation methods are advantageous in this context because they provide standardized replicates, specific species isolation, and easy sampling. This study aimed to understand the ecological process using a microcosm system with pesticide concentrations similar to those found in the soil, in contrast to high doses, from the isolation of the enriched community. The atrazine concentrations used were 0.02 mg/kg (control treatment), 300 ng/kg (treatment 1), and 3000 ng/kg (treatment 2), using a 28-day microcosm system. Ultimately, the isolation resulted in 561 fungi classified into 76 morphospecies. The Ascomycota phylum was prevalent, with Purpureocillium, Aspergillus, and Trichoderma being consistently isolated, denoting robust and persistent genera. Diversity analyses showed that the control microcosms displayed more distinct fungal morphospecies, suggesting the influence of atrazine on fungal communities. Treatment 2 (higher atrazine concentration) showed a structure comparable to that of the control, whereas treatment 1 (lower atrazine concentration) differed significantly, indicating that atrazine concentration impacted community variance. Higher atrazine addition subtly altered ligninolytic fungal community dynamics, implying its potential for pesticide degradation. Finally, variations in atrazine concentrations triggered diverse community responses over time, shedding light on fungal resilience and adaptive strategies against pesticides.

High soil pH and excess CaCO₃ are major contributors to calcareous soil limitations on crops' access to essential nutrients, especially phosphorus (P) and micronutrients, which in turn impact pulses yields and growth. The purpose of this study was to determine the effect of bio sulfur granules (BSG) on the growth of black gram and the availability of nutrients in calcareous vertisols deficient in sulfur. BSG was developed by using sulfur-oxidizing bacteria (SOB) and elemental sulfur (ES) through an incubation study. Developed BSG was tested in a pot and field conditions to evaluate their effectiveness on black gram growth and yield. In the incubation study, soil treated with Methylobacterium thiocyanatum VRI7-A4 and ES (40 kg S/ha) significantly decreased pH and increased available S (SO₄^2-) in calcareous soils. After 40 days of incubation, the solubility of P, Fe, and Zn was greatly increased by the addition of ES @ 40 kg S/ ha in combination with M. thiocyanatum VRI7-A4 or Pandoraea thiooxydans ATSB16. Black gram in S-deficient calcareous soil was improved by the application of BSG (ES @ 40 kg S/ ha with M. thiocyanatum VRI7-A7) in terms of root and shoot lengths, nodule number, plant biomass, pod yield, and biological yield as compared to control. The same treatment greatly increased plant nutrient intake as well as the concentrations of P, Fe, and Zn in the soil. The results showed that the addition of BSG granules (ES @ 40 kg S/ha + M. thiocyanatum VRI7-A4) to calcareous vertisol deficient in S enhanced the nutrient solubility through S oxidation. The developed bio sulfur granules may be added to the fertilizer schedule of the pulses growers to get improved crop growth and yield of black gram in calcareous soil.

Among carotenoids, ꞵ-carotene has the highest biological activity and is found as an all-trans isomer in many biological systems. Blakeslea trispora is a microorganism that is of interest to industries for the commercial production of ꞵ-carotene. This study investigated the effect of different bacteria on carotenogenesis in B. trispora. The B. trispora bisexual mold was cultured in a production medium, and different bacterial cells were added to it after 24 h. Then, the culture conditions and the culture medium were optimized in the presence of the selected bacteria using the experimental design. The percentage of carotenoids obtained from the mixed culture was determined using high-performance liquid chromatography (HPLC). Results showed that Kocuria rhizophila had the greatest effect on increasing the production of carotenoids in B. trispora. The highest content of carotenoids obtained during optimization was 770 ± 7.5 mg/L, a 6.8-fold increase compared to the control. HPLC analysis of carotenoids indicated the presence of two main peaks, ꞵ-carotene and ^γ-carotene, in which the primary carotenoid was ꞵ-carotene followed by ^γ-carotene with a lower content. Therefore, due to the importance of ꞵ-carotene in industry, the use of biostimulants is one of the appropriate strategies to increase the production of this pigment in industry.

The positive detection rate of blood metagenomic next-generation sequencing (mNGS) was still too low to meet clinical needs, while pus from the site of primary infection may be advantageous for identification of pathogens. To assess the value of mNGS using pus in patients with sepsis, thirty-five samples were collected. Pathogen identification and mixed infection diagnosis obtained by use of mNGS or cultivation methods were compared. Fifty-three aerobic or facultative anaerobes, 59 obligate anaerobes and 7 fungi were identified by the two methods. mNGS increased the accuracy rate of diagnosing aerobic or facultative anaerobic infections from 44.4% to 94.4%; mNGS also increased the sensitivity of diagnosing obligate anaerobic infections from 52.9% to 100.0%; however, mNGS did not show any advantage in terms of fungal infections. Culture and mNGS identified 1 and 24 patients with mixed infection, respectively. For obligate anaerobes, source of microorganisms was analyzed. The odontogenic bacteria all caused empyema (n = 7) or skin and soft tissue infections (n = 5), whereas the gut-derived microbes all caused intra-abdominal infections (n = 7). We also compared the clinical characteristics of non-obligate anaerobic and obligate anaerobic infection groups. The SOFA score [9.0 (7.5, 14.3) vs. 5.0 (3.0, 8.0), P = 0.005], procalcitonin value [4.7 (1.8, 39.9) vs. 2.50 (0.7, 8.0), P = 0.035], the proportion of septic shock (66.7% vs. 35.3%, P = 0.044) and acute liver injury (66.7% vs. 23.5%, P = 0.018) in the non-obligate anaerobic infection group were significantly higher than those in the obligate anaerobic infection group. In patients with sepsis caused by purulent infection, mNGS using pus from the primary lesion may yield more valuable microbiological information.

Multidrug resistant (MDR) bacteria are recognized to be one of the most important problems in public health. The outer membrane permeability is a critical intrinsic mechanism of bacterial resistance. In addition, bacteria produce a small number of dormant persister cells causing multidrug tolerance that reduces antimicrobial efficacy. This study aimed to evaluate the inhibitory effects of the combination of aromatic isothiocyanates (ITCs) with membrane-active agents on bacterial persisters and MDR Gram-negative bacteria. Our study demonstrated that membrane-active agents, particularly ethylenediaminetetraacetic acid (EDTA) synergistically enhanced the inhibitory activity of aromatic benzyl ITC and phenethyl ITC against most Gram-negative bacteria strains with fractional inhibitory concentration index values ranging from 0.18 to 0.5 and 0.16 to 0.5, respectively, and contributed to an 8- to 64-fold minimal inhibitory concentration reduction compared with those of aromatic ITCs alone. The EDTA-aromatic ITCs combination effectively reduced the survival rates of tested bacteria and significantly eradicated bacterial persisters (p = 0.033 and 0.037, respectively). The growth kinetics analysis also supported the enhanced inhibitory effect of EDTA-aromatic ITCs combination against tested bacteria. Our results suggested an alternate treatment strategy against Gram-negative bacteria, promoting the entry of aromatic ITCs into bacterial cytoplasm to facilitate bacterial clearance and thus preventing the development of bacterial resistance.

The bacterial secretome represents a comprehensive catalog of proteins released extracellularly that have multiple important roles in virulence and intercellular communication. This study aimed to characterize the secretome of an environmental isolate Pseudomonas aeruginosa S-8 by analyzing trypsin-digested culture supernatant proteins using nano-LC-MS/MS tool. Using a combined approach of bioinformatics and mass spectrometry, 1088 proteins in the secretome were analyzed by PREDLIPO, SecretomeP 2.0, SignalP 4.1, and PSORTb tool for their subcellular localization and further categorization of secretome proteins according to signal peptides. Using the gene ontology tool, secretome proteins were categorized into different functional categories. KEGG pathway analysis identified the secreted proteins into different metabolic functional pathways. Moreover, our LC-MS/MS data revealed the secretion of various CAZymes into the extracellular milieu, which suggests its strong biotechnological applications to breakdown complex carbohydrate polymers. The identified immunodominant epitopes from the secretome of P. aeruginosa showed the characteristic of being non-allergenic, highly antigenic, nontoxic, and having a low risk of triggering autoimmune responses, which highlights their potential as successful vaccine targets. Overall, the identification of secreted proteins of P. aeruginosa could be important for both diagnostic purposes and the development of an effective candidate vaccine.

Apple replant disease (ARD) is a significant factor restricting the healthy development of the apple industry. Biological control is an important and sustainable method for mitigating ARD. In this study, a strain of Paenibacillus polymyxa GRY-11 was isolated and screened from the rhizosphere soil of healthy apple trees in old apple orchards in Shandong Province, China, and the effects of strain GRY-11 on soil microbial community and ARD were studied. The result showed that P. polymyxa GRY-11 could effectively inhibit the growth of the main pathogenic fungi that caused ARD, and the inhibition rates of the strain against Fusarium moniliforme, Fusarium proliferatum, Fusarium solani, and Fusarium oxysporum were 80.00%, 71.60%, 75.00%, and 70.00%, respectively. In addition, the fermentation supernatant played an active role in suppressing the growth of pathogenic fungi. The results of the pot experiment showed that the bacterial fertilizer of the GRY-11 promoted the growth of Malus hupehensis seedlings, improved the activity of protective enzymes in plant roots, enhanced the soil enzyme content, and optimized the soil microbial environment. In general, the GRY-11 can be used as an effective microbial preparation to alleviate ARD. Our study offers novel perspectives for the prevention of ARD.

The objective of this study was to isolate, identify, and assess the safety and functionality in vitro of putative probiotic bacterial strains. Isolation procedures were based on standard methods using elective and selective media. The isolates were identified by comparative 16S rRNA sequencing analysis while their safety was determined according to the safety tests recommended by the FAO/WHO such as antibiotic resistance, hemolysin, and biogenic amine production. Most of the isolates did not pass the in vitro safety tests; therefore, only Lactiplantibacillus plantarum (from ant intestine and cheese), Lacticaseibacillus paracasei (from goat milk and kimchi), Enterococcus faecium (from chili doenjang and vegetables with kimchi ingredients), Limosilactobacillus fermentum (from saliva), and Companilactobacillus alimentarius (from kimchi) were identified and selected for further studies. The isolates were further differentiated by rep-PCR and identified to the strain level by genotypic (16S rRNA) and phenotypic (Gen III) approaches. Subsequently, the strain tolerance to acid and bile was evaluated resulting in good viability after simulated gastrointestinal tract passage. Adhesion to mucin in vitro and the presence of mub, mapA, and ef-tu genes confirmed the adhesive potential of the strains and the results of features associated with adhesion such as hydrophobicity and zeta potential extended the insights. This study reflects the importance of fermented and non-fermented food products as a promising source of lactic acid bacteria with potential probiotic properties. Additionally, it aims to highlight the challenges associated with the selection of safe strains, which often fail in the in vitro tests, thus hindering the possibilities of "uncovering" novel and safe probiotic strains.