International Microbiology最新文献

Microplastics are widely recognized as persistent and pervasive contaminants that endanger human health and ecosystems. Traditional remedial techniques are problematic due to high costs and inefficiency. One sustainable method of dissolving tough polymers into recyclable parts is through microbial and enzymatic engineering. Recent advances in genome-editing technologies, enzyme redesign, and synthetic biology particularly CRISPR-based systems have transformed the way we approach enhancing the efficiency of biodegradation. Recent CRISPR applications, such as base editing and promoter modification, have improved the stability and expression of enzymes, accelerating the catalytic activity of PET hydrolases, including PETase and cutinase. To enable scalable plastic biodegradation, this review combines hybrid CRISPR-based systems with microbial and enzyme engineering techniques. The goals of computational and machine learning-based enzyme design is thermostability and substrate adaptation, while hybrid microbial communities made up of modified bacteria and fungi improve degradation through cooperative processes. Furthermore, combining synthetic biology with hybrid remediation techniques, such as biofilm reactors and enzyme-nanoparticle conjugates, links laboratory research developments with real-world applications. However, issues remain regarding the scalability of polyethylene (PE) and polystyrene (PS) degradation, biosafety standards for genetically modified organisms (GMOs), and environmental hazards associated with degradation byproducts. To effectively manage plastic waste, future research should focus on creating thermostable enzymes, forming synthetic consortia guided by multi-omics, and developing safe hybrid bio-physical systems that support circular bio economy models.

Marine sponges rely on their intricate and varied bacterial communities to sustain their ecological balance and health. The structure and role of bacterial communities are affected by environmental factors and sponge species. One ecological function of symbiotic bacteria is to prevent the formation of biofilms by pathogenic bacteria that could potentially compromise sponges' health. This study investigates the antibiofilm activities of symbiotic bacteria isolated from seagrass associated sponges residing under dynamic conditions. Bacteria were isolated from various sponge species from seagrass ecosystem and assessed for their capacity to inhibit biofilm-forming bacteria discovered on submerged wood and fiber panels in contaminated marine habitats. A double-layer experiment was conducted utilizing Zobell 2216E media to evaluate antagonism among 44 bacterial isolates derived from nine sponge species. Twenty-five isolates exhibited inhibitory activity against five biofilm-forming bacteria, with FP2 being the most substantially inhibited strain. Eight symbiotic bacteria exhibited high to very high antibiofilm activity. Statistical analysis revealed groupings of bacteria with similar inhibition patterns, indicating a potential association with specific inhibitory mechanisms. The 16 S rRNA sequencing research revealed that the symbiotic bacteria are categorized into the Firmicutes and α- and γ-Proteobacteria groups, with potential unique strains identified. The findings suggest that bacteria from seagrass-associated sponges and their secondary metabolites could aid in the development of compounds for biofilm prevention and management.

Soil salinity postures a significant threat to agricultural productivity, exacerbating universal food security challenges. This study investigated the ability of the halophilic bacterium Halobacillus trueperi RSK CAS9 to alleviate salt stress over the exopolysaccharides (EPS) and indole-3-acetic acid (IAA) production. Growth assays revealed that bacterial proliferation decreased with increasing NaCl concentration, demonstrating moderate tolerance at lower concentrations (100-200 mM NaCl). Optimization using response surface methodology (RSM) identified pH 8.0, 15% sucrose, and a 96 h incubation period as optimal conditions for maximal EPS production (272.2 mg/L). Under various NaCl concentrations, the EPS yield peaked at 202.2 mg/L at 200 mM NaCl, suggesting enhanced stress tolerance at moderate salinity levels. SEM analysis showed morphological changes, indicating adaptive biofilm formation. Analysis of FT-IR confirmed the occurrence of hydroxyl, carboxyl, and glycosidic bonds, crucial for EPS's protective role. Additionally, IAA production peaked at 1.42 µg/mL under low saline conditions (100 mM NaCl) and decreased at higher salinities, underscoring the bacterium's potential in plant hormone responses under salted stress. Collectively, these results sustenance the potential application of halophilic bacteria as sustainable agents for managing saline stress in agricultural systems.

Trichoderma frianum sp. nov., a wood-inhabiting species from India, is described based on morphological characteristics and molecular phylogenetic analyses. This taxon is congruent with the morphological species concept of T. harzianum sensu lato, characterized by pyramidal conidiophores and cruciate phialidic whorls with fewer than five phialides. However, it differs by producing verticils that bear up to seven divergent phialides. Phylogenetic analyses based on a combined dataset of the translation elongation factor 1-alpha (tef1) and RNA polymerase II second-largest subunit (rpb2) gene regions confirmed the placement of T. frianum within the T. harzianum species complex (THSC) of the Harzianum clade. This species forms a sister lineage to T. anaharzianum, T. neotropicale, T. lixii, T. xixiacum, and T. lentinulae, with the pairwise homoplasy index (PHI) test supporting their classification as distinct species. Comparative sequence analyses revealed that T. frianum possesses unique tef1 and rpb2 sequences that do not meet the ∃!(rpb2₉₉ ≅ tef1₉₇) standard for known species, fulfilling the criteria of the International Commission on Trichoderma Taxonomy (ICTT) for new species delineation. However, deviations from the tef1 and rpb2 thresholds were observed in some comparisons within THSC and are discussed. Functionally, T. frianum exhibited strong antagonistic activity against major Eucalyptus pathogens and showed robust growth under high-salinity conditions in vitro, suggesting its potential for biocontrol and stress-resilient forestry systems.

Fusarium wilt of banana, caused by Fusarium oxysporum f. sp. cubense Tropical Race 4 (Foc TR4), remains a severe global threat to banana production. This study aimed to identify and evaluate native fungal and actinomycete isolates from banana-growing regions in southern Vietnam for their potential as biological control agents against Foc TR4. Eighteen isolates were screened, and five antagonistic strains (Trichoderma harzianum D-LD, T. asperelloides G-BT, Penicillium menonorum LA02-2, Streptomyces luteogriseus XK3, and S. mutabilis XK4) were selected for morphological, molecular, enzymatic, and greenhouse evaluations. Both T. harzianum and T. asperelloides exhibited strong in vitro inhibition of Foc TR4 (87.4% and 84.2%, respectively) through the production of cell wall degrading enzymes, notably chitinase and protease. In greenhouse trials, S. mutabilis XK4 demonstrated the highest disease suppression (AUDPC reduction > 80%, wilt incidence 28%) and enhanced plant growth, indicating a dual role in biocontrol and plant growth promotion. Penicillium menonorum LA02-2 showed moderate inhibition (50.9%) and growth-enhancing effects, highlighting its potential as a supplementary component in microbial consortia. Scanning electron microscopy confirmed mycoparasitic interaction between T. asperelloides G-BT and Foc TR4 hyphae, whereas S. luteogriseus XK3 and S. mutabilis XK4 caused severe hyphal damage through antibiosis and enzymatic lysis. This study reports the first isolation of P. menonorum, S. luteogriseus, and S. mutabilis from Vietnamese banana soils and identifies S. mutabilis XK4 as a promising candidate for developing bio-formulations against Foc TR4. These findings highlight the potential of indigenous microbial resources for sustainable Fusarium wilt management in Cavendish banana cultivation.

Exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) hold significant potential across multiple industries, with applications extending from food technology to pharmaceuticals. Although numerous studies have explored their technological and biological functionalities such as thickening, stabilization, and health-promoting effects the existing literature remains fragmented regarding the biosynthesis mechanisms, genetic regulation, and structure function relationships of LAB-derived EPS. Moreover, current reviews often address these aspects separately, lacking an integrated perspective that connects molecular mechanisms to practical applications. This review fills these gaps by providing a comprehensive and unified analysis of LAB produced EPS, covering their classification, biosynthetic pathways (including the influence of genetic determinants), structural diversity, technological roles, and biological activities. It also evaluates recent advances in production optimization and analytical characterization techniques. By consolidating dispersed knowledge, this review offers a holistic framework that links molecular insights with functional outcomes, thus supporting the rational design of LAB strains for targeted EPS production. The focus on LAB EPS is particularly relevant due to their Generally Recognized as Safe (GRAS) status, which enhances their applicability in food and health-related sectors compared to microbial EPS from other sources. Ultimately, this review contributes a critical synthesis that guides future research and industrial innovation, aligning with the growing demand for naturally derived, multifunctional, and health-promoting biopolymers.

Moniliophthora roreri is a major fungal pathogen that significantly reduces cacao yields in Colombia. Currently, farmers rely solely on fungicides for its control, and environmentally friendly alternatives remain limited. The objective of this study was to assess the antagonistic potential of yeasts isolated from diverse niches in Colombia against M. roreri as a first step toward developing sustainable biocontrol strategies. Initially, the pathogen was identified at the molecular level. Subsequently, seven yeast strains belonging to the genera Wickerhamomyces, Naganishia, Pichia, and Metschnikowia were assessed for antifungal activity against M. roreri, volatile organic compounds (VOCs) production, and enzymatic activities. Although none of the strains inhibited fungal growth through direct confrontation, VOC-mediated antagonism in dual-culture assays resulted in pathogen growth inhibition ranging from 38% to 98%. Glucanase, protease, and cellulase activities were detected to varying degrees among the isolates. Pichia kluyveri Lv125, which exhibited the strongest inhibitory effect, was selected for VOC characterization using gas chromatography-mass spectrometry (GC-MS). Antagonistic VOCs produced after 15 days of incubation included 1-butanol, 3-methylbutanoic acid, butanoic acid, 3-methyl-1-butanol, 3-methyl acetate, and phenylethyl alcohol. These findings highlight the potential of yeasts as biological control agents and support their use as an alternative management strategy against M. roreri in cacao plantations.

Acinetobacter baumannii, a pathogen for humans and animals, possesses a tremendous potential to survive under hostile conditions. We studied the effect of temperature, nutrient deprivation, and desiccation on the survival of A. baumannii ATCC 19606^T by monitoring variations in cellular counts and in cell length and analyzing cell envelope subproteome during the survival process. Nutrient deprivation alone does not appear to have a negative effect on A. baumannii survival, but incubation at 37 °C in an aqueous solution provoked loss of culturability, as well as a marked increase in cell length. Although a high stability of the membrane subproteome was observed, even under environmental conditions that promote morphological changes and loss of culturability, the expression of some membrane proteins did change upon exposure to the stress. Signal peptidase I and fimbrial protein became undetectable in almost all the conditions examined, while EF-Tu (in all conditions) and MinD (in populations incubated at 37 °C) were overexpressed. The great capacity for survival displayed by A. baumannii under adverse conditions may be explained, at least in part, by its capacity to maintain the expression levels of most of its cell envelope proteins and regulate a few others.