Journal of Basic Microbiology最新文献

Poly(methyl methacrylate) (PMMA) resins are widely used in medical and dental applications. Their susceptibility to bacterial biofilm formation poses significant challenges related to material degradation and infection risk. This study investigated the effects of Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus) biofilms on PMMA resin surface properties over a 45-day period at 35°C. The study examined various parameters including biofilm adhesion, morphology, surface roughness, hydrophobicity, solid fraction, and zeta potential. PMMA resin specimens were inoculated with bacteria and incubated for 45 days. Biofilm adhesion was visually assessed, while surface characterization was conducted using scanning electron microscopy (SEM), atomic force microscopy (AFM), roughness analysis, contact angle measurements, solid fraction determination, and zeta potential analysis. The P. aeruginosa and S. aureus isolates were selected based on their biofilm-positive characteristics, which were further confirmed using Congo red and biofilm formation assays through crystal violet staining and spectrophotometric analysis. The results demonstrated robust biofilm adhesion on PMMA surfaces. SEM and AFM imaging revealed textured surfaces with elevated structures and depressions within the biofilm matrix. Biofilm-exposed resins exhibited significantly increased roughness (Ra = 164.5 nm, Rq = 169.5 nm) and hydrophobicity (mean angle = 85.5°-90.5°) compared to control samples (Ra = 38-50 nm, angle = 55°). Solid fraction measurements indicated a denser biofilm matrix on exposed resins (0.908) compared to controls (0.65). Additionally, zeta potential values were more negative for biofilm-exposed resins (mean = -84.2 mV) than controls (-45.0 mV). These findings underscore the substantial alterations in PMMA resin surface properties induced by bacterial biofilms, emphasizing the critical need for strategies to prevent biofilm formation and mitigate associated risks in healthcare settings. Future research should focus on developing anti-biofilm coatings or treatments to preserve the integrity and functionality of PMMA materials.

Present study aimed to identify arsenic (As)-resistant bacterial strains that can be used to mitigate arsenic stress. A bacterium Bacillus mycoides NR5 having As tolerance limit of 1100 mg L^-1 was isolated from Nag River, Maharashtra, India. It was also equipped with plant growth-promoting (PGP) attributes like phosphate solubilization, siderophores, ammonia, and nitrate reduction, with added antibiotic tolerance. Furthermore, scanning electron microscopy (SEM) and transmission electron micrograph (TEM) suggested biosorption as possible mechanisms of arsenic tolerance. A strong peak in FTIR spectra at 3379.0 corresponding to amine in As-treated NR5 also indicated metal interaction with cell surface protein. Amplification of arsenic reductase gene in NR5 further suggested intracellular transformation of As speciation. Moreover, As tolerance capability of NR5 was shown in spinach plants in which the bacterium effectively mitigated 25 ppm As by producing defense-related proline molecules. Evidence from SEM, TEM, and FTIR, concluded biosorption possibly the primary mechanism of As tolerance in NR5 along with the transformation of arsenic. B. mycoides NR5 with PGP attributes, high As tolerance, and antibiotic resistance mediated enhanced As tolerance in spinach plants advocated that the strain can be a better choice for As bioremediation in contaminated agricultural soil and water.

Mythimna separata is a destructive polyphagous pest of field crops. Insecticides are generally applied for its control which not only negatively affect natural enemies and the environment and cause resistance in the insect pests. There is a need for the friendly method which is safe for the environment and life. Currently, entomopathogenic fungi are being used as biological control agents for different insects. The influence of Isaria fumosorosea on survival, life table parameters, and enzymatic activities of M. separata were assessed. On the seventh day post-treatment, the highest concentration 3 × 10⁸ spores/mL^-1 caused the 92.5% larval mortality. The effect of LC₁₅ and LC₅₀ of I. fumosorosea were recorded on parental generation (F₀) and first filial generation (F₁) of M. separata. The life table parameters of F₁ showed a decreasing trend in the intrinsic rate (r), net reproductive rate (R_o), mean generational time (T), total larval duration, and fecundity ratio in treated groups. In LC₁₅ and LC₅₀, groups the average fecundity ratio was 319.2 and 191.18 eggs/female, respectively. The activities of detoxifying enzymes were concentration-dependent and highest activities were recorded on the third day. I. fumosorosea negatively affected the growth parameters of M. separata and can be included in M. separata management program.

Peanut (Arachis hypogaea L.) is an important cash and oil seed crop, mostly distributed in arid and semi-arid areas. In recent years, due to the influence of atmospheric circulation anomalies and other factors, drought has become frequent and increasingly serious in China. This has posed serious challenges to peanut production. The objective of this study was to investigate the potential of the endophytic fungus Piriformospora indica to form a symbiotic relationship with peanut plants and to evaluate the drought tolerance of P. indica-colonized peanut plants subjected to a simulated drought stress treatment using 20% polyethylene glycol 6000 (PEG6000). The endophytic fungus P. indica affected the physiological characteristics of the host plant by colonizing the plant roots, thereby conferring greater resistance to drought stress. This fungus strongly colonized the roots of peanuts and was found to enhance root activity after 24 h of P. indica colonization under PEG6000. Catalase (CAT) and peroxidase (POD) activities were increased at 24 h in peanut leaves colonized with P. indica. Expression of drought-related genes, such as AhNCED1, AhP5CS, and DREB2A was upregulated at 24 h of P. indica colonization. In addition, after PEG6000 treatment, proline, soluble protein, and abscisic acid (ABA) concentrations in plants were increased, while the accumulation of malondialdehyde (MDA), and hydrogen peroxide (H₂O₂) was decreased in P. indica colonized peanut. In conclusion, P. indica mediated peanut plant protection against the detrimental effects of drought resulted from enhanced antioxidant enzyme activities, and the upregulated expression of drought-related genes for lower membrane damage.

In India, the shot-hole borer, Euwallacea fornicates, commonly known as the tea borer, infests the galleries of tea plant twigs under natural conditions and is a major pest of tea. The current investigation focuses on the antagonistic ability of Bacillus subtilis to directly inhibit the growth of plant pathogens in two different climatic regions of tea-growing area. The evaluation reveals that (a) B. subtilis can directly suppress the growth of plant pathogens (b) in the in vitro evaluation; the B. subtilis suppressed the growth of the Fusarium ambrossium, which is the nourishment for the ambrosia beetle, (c) it also revealed that the antagonistic microbes and the entomopathogens are able to control the pest population of the shot hole borer of tea. The impact of B. subtilis on mycelial growth, sporulation, and spore germination of F. ambrosium in agar medium was observed. In the field condition on the post-treatment assessments shows an average decline of 40% in both foliar and soil drenching. Hence, we recommend the antagonistic bacterium B. subtilis for including as an IPM for the management of shot hole borer in tea.

The unique tissue structure of pathogenic bacteria biofilm plays an important role in its pathogenicity and bactericide resistance. Inhibition or destruction of biofilm formation of pathogenic bacteria is of great significance for the control of plant bacterial diseases. In this study, Paracidovorax citrulli was inoculated into KB medium containing acetic acid, and after shaking at 28°C and 55 r/min for 48 h, it was found that the content of extracellular polysaccharide, extracellular protein and extracellular DNA (eDNA) decreased with the increase of acetic acid concentration, which resulted in the decrease of biofilm formation, it is not even possible to form biofilms on plastic slides. When the final concentration of acetic acid in the culture medium was greater than or equal to 0.5 mg/mL, there was no biofilm on the plastic slides. Therefore, the use of acetic acid as an inhibitor of P. citrulli has a good potential for control of bacterial fruit blotch.

This study aimed to explore the diversity, root morphology, and colonization of arbuscular mycorrhizal fungi (AMF) associated with eight medicinal plants of the Lamiaceae family. Rhizospheric soil and root samples were collected from eight species of Lamiaceae plants for AMF analysis. The results indicate that root colonization was not directly related to the number of AMF spores in the rhizosphere. However, a significant correlation was found between the percentage of root colonization and the number of AMF species present in the individual plants. The highest percentage of colonization (86.67 ± 1.92%) and the greatest number of AMF species were observed in Micromeria fructicosa, while the lowest colonization (27.67 ± 6.22%) was recorded in Mentha arvensis. The highest spore count was recorded in Thymus vulgaris (120 ± 27.01), whereas the lowest was found in Melissa officinalis (84 ± 17.20). Among the identified AMF species, Glomus was the most dominant, representing 35.7% of all AMF species across the eight medicinal plants. The maximum AMF spore density was observed in M. fructicosa and lowest in M. arvensis. The study suggests that AMF can significantly enhance medicinal plant growth by ensuring a consistent supply of nutrients and water, thereby supporting the sustainable cultivation of medicinal plants to meet the growing demand.

Bacteria and fungi are natural sources of metabolites exhibiting diverse bioactive properties such as wound healing, antioxidative, antibacterial, antifungal, anti-inflammatory, antidiabetic, and anticancer activities. Two important groups of bacteria or fungi-derived metabolites with wound-healing potential are polysaccharides and peptides. In addition to bacteria-derived cellulose and hyaluronic acid and fungi-derived chitin and chitosan, these organisms also produce different polysaccharides (e.g., exopolysaccharides) with wound-healing potential. The most commonly used bacterial peptides in wound healing studies are bacteriocins and lipopeptides. Bacteria or fungi-derived polysaccharides and peptides exhibit both the in vitro and the in vivo wound healing potency. In the in vivo models, including animals and humans, these metabolites positively affect wound healing by inhibiting pathogens, exhibiting antioxidant activity, modulating inflammatory response, moisturizing the wound environment, promoting the proliferation and migration of fibroblasts and keratinocytes, increasing collagen synthesis, re-epithelialization, and angiogenesis. Therefore, peptides and polysaccharides derived from bacteria and fungi have medicinal importance. This study aims to overview current literature knowledge (especially within the past 5 years) on the in vitro and in vivo wound repair potentials of polysaccharides and peptides obtained from bacteria (Actinobacteria, Bacteroidetes, Cyanobacteria, Firmicutes, and Proteobacteria) and fungi (yeasts, filamentous microfungi, and mushrooms).

A rod-shaped, motile, Gram-stain-positive bacterial strain RKN2^T, was isolated from gut of silver carp (Hypophthalmichthys molitrix) residing in Gobindsagar reservoir, Himachal Pradesh, India. Having the greatest sequence similarity to Sporosarcina koreensis F73^T (98.51%), Sporosarcina luteola Y1^T (98.4%) and Sporosarcina aquimarina SW28^T (98.36%), the 16S rRNA gene phylogeny confirmed the belonging of strain RKN2^T to genus Sporosarcina. Digital DNA-DNA hybridization values were 21.7%, 20.6%, and 19.2%, and average nucleotide identity values were 76.42%, 80.16%, 76.51%, of strain RKN2^T with Sporosarcina koreensis F73^T, Sporosarcina luteola Y1^T, and Sporosarcina aquimarina SW28^T, respectively. The genomic analysis of strain RKN2^T showed various biological properties including nitrate reduction, genes responsible for carbohydrate-active enzymes production, antimicrobial compounds, as well as potential metabolism of aromatic compounds and heavy metals. G+C composition of RKN2^T genome was 52.7%. This strain can grow in temperatures between 10°C and 40°C (optimum, 28°C-30°C), NaCl concentrations up to 6.0% (w/v), and 6.0-8.0 (optimum, 6.5-7.5) pH range. MK-7 was the dominant respiratory quinone, A-4 type cell wall peptidoglycan was present with anteiso-C_15:0, iso-C_15: 0, and anteiso-C17:0 being the major fatty acids and Lys-Glu being main amino acids. Diphosphatidylglycerol, phosphatidylglycerol, and phosphatidylethanolamine were the strain RKN2^T's three main polar lipids. The strain is a novel species under genus Sporosarcina based on polyphasic approach and the name Sporosarcina hypophthalmichthys sp. nov. is given for strain RKN2^T. RKN2^T is a type strain (= MCC 4365^T = JCM34522^T = CCM9112^T).

Biofilms are complex communities of microorganisms that can cause significant challenges in various settings, including industrial processes, environmental systems, and human health. The protective nature of biofilms makes them resistant to traditional anti-biofilm strategies, such as chemical agents, mechanical interventions, and surface modifications. To address the limitations of conventional anti-biofilm methods, researchers have explored emerging strategies that encompass the use of natural compounds, nanotechnology-based methods, quorum-sensing inhibition, enzymatic degradation, and antimicrobial photodynamic/sonodynamic therapy. There is an increasing focus on combining multiple anti-biofilm strategies to combat resistance and enhance effectiveness. Researchers are continuously investigating the mechanisms of biofilm formation and developing innovative approaches to overcome the limitations of conventional anti-biofilm methods. These efforts aim to improve the management of biofilms and prevent infections while preserving the environment. This study provides a comprehensive overview of the latest advancements in anti-biofilm strategies. Given the dynamic nature of this field, exploring new approaches is essential to stimulate further research and development initiatives. The effective management of biofilms is crucial for maintaining the health of industrial processes, environmental systems, and human populations.