Search Results (81)

The growing emphasis on sustainability, regional distinctiveness, and spontaneous fermentation in winemaking necessitates a more comprehensive understanding of local yeast populations and their functional mechanisms. In total, 115 indigenous yeast strains were examined for their enzymatic activities of potential vitivinicultural significance. The yeasts were screened for chitinase activity (biocontrol potential), glycosidase activity (terpene release), β-lyases (thiol release), and sulfite reductases (off-flavor formation), followed by quantitative analysis of the selected subsets. Yeasts were further evaluated for inhibition of fungal mycelial growth, VOC-mediated inhibition, and tolerance to commonly applied fungicides. Pre-field selection was refined using the niche overlap index and grapevine leaf disc assay. The results confirmed chitinolytic activity in four species; all strains exhibited hydrolase activities, with H. uvarum 116 displaying the highest cell-associated activity (6.32 U/g), while T. delbrueckii Sut94 showed the highest extracellular activity (1.36 U/g). β-glucosidase and β-lyase activities were widespread, whereas hydrogen sulfide production was infrequent. P. guilliermondii ZIM 624 showed the most comprehensive overall enzymatic profile, together with strong inhibition patterns. A field trial on Pinot cultivars (V. vinifera L.) further evaluated P. guilliermondii ZIM 624 within an integrated disease management approach, with responses being more pronounced in ‘Pinot noir’ than in ‘Pinot gris’. Full article

The highly chitinolytic marine bacterium Vibrio jasicida KMM 6832, which exhibits potent antifungal activity, possesses an atypical Glycosyl Hydrolase family 19 (GH19) chitinase (ChitVjs). This is the first report of a GH19 gene in V. jasicida, an enzyme generally absent in this species and rare within the Harveyi clade. Phylogenetically, ChitVjs-like enzymes from the genera Vibrio and Aeromonas form a distinct cluster, separate from typical plant and bacterial GH19 counterparts. Despite high sequence identity (80–94%) with characterized homologs from V. parahaemolyticus and V. cholerae, ChitVjs is distinguished by its obligate halophilicity (optimum 0.3–0.4 M NaCl), an acidic isoelectric point (pI 4.72), and a broader cation-activation profile (K⁺, Ni²⁺, Ca²⁺, Cu²⁺, Co²⁺). The recombinant ChitVjs was produced in E. coli as a soluble 63 kDa protein. It functions as a stable, salt-dependent endo-chitinase/chitosanase, exhibiting optimal activity at 40 °C and pH 7.0. The enzyme displays high affinity for colloidal chitin (K_M 0.377 mg·mL⁻¹), is activated by DTT and Tween 80, and shows moderate stability in organic solvents. Furthermore, unlike its primarily catabolic relatives, ChitVjs suppresses conidial germination in marine-derived Aspergillus strains. These findings suggest that ChitVjs significantly contributes to the competitive fitness of V. jasicida KMM 6832 in high-salinity marine environments through both nutrient acquisition and antagonism. Full article

Potato (Solanum tuberosum L.) is a key staple crop in the Peruvian Andes, but its productivity is threatened by fungal pathogens such as Rhizoctonia solani and Alternaria alternata. In this study, 71 native bacterial strains (39 from phyllosphere and 32 from rhizosphere) were isolated from potato plants across five agroecological zones of Peru and characterized for their plant growth-promoting (PGPR) and antagonistic traits. Actinomycetes demonstrated broader enzymatic profiles, with 2ACPP4 and 2ACPP8 showing high proteolytic (68.4%, 63.4%), lipolytic (59.5%, 60.6%), chitinolytic (32.7%, 35.5%) and amylolytic activity (76.3%, 71.5%). Strain 5ACPP5 (Streptomyces decoyicus) produced 42.8% chitinase and solubilized both dicalcium (120.6%) and tricalcium phosphate (122.3%). The highest IAA production was recorded in Bacillus strain 2BPP8 (95.4 µg/mL), while 5ACPP6 was the highest among Actinomycetes (83.4 µg/mL). Siderophore production was highest in 5ACPP5 (412.4%) and 2ACPP4 (406.8%). In vitro antagonism assays showed that 5ACPP5 inhibited R. solani and A. alternata by 86.4% and 68.9%, respectively, while Bacillus strain BPP4 reached 51.0% inhibition against A. alternata. In greenhouse trials, strain 4BPP8 significantly increased fresh tuber weight (11.91 g), while 5ACPP5 enhanced root biomass and reduced stem canker severity. Molecular identification confirmed BPP4 as Bacillus halotolerans and 5ACPP5 as Streptomyces decoyicus. These strains represent promising candidates for the development of bioinoculants for sustainable potato cultivation in Andean systems. Full article

The identification and quantification of chitinolytic activity in microorganisms is critical for advancing biological control strategies against arthropod pests and fungal pathogens. However, current laboratory methods designed for fast detection of chitinolytic microorganisms are often time-consuming, produce low-quality results and lack sensitivity. Here, we report the development of a novel fluorogenic culture medium incorporating a chemically modified chitinase substrate, N-fluoresceyl poly-D-glucosamine, which allows for a highly sensitive chitinase assay, enabling both qualitative and quantitative fluorescent detection of chitinase activity in situ. This substrate is synthesized through covalent conjugation of poly-D-glucosamine with fluorescein isothiocyanate under alkaline conditions, resulting in an insoluble polymer that becomes fluorescent upon enzymatic hydrolysis by chitinases. When supplemented with culture media, the modified fluorogenic substrate serves as the sole carbon source, selectively supporting the growth of chitinolytic microorganisms. Enzymatic activity is visualized under longwave UV light and can be quantitatively measured via spectrophotometric (493 nm) or fluorometric (530 nm) methods. Validation using characterized entomopathogenic chitinolytic strains of the fungi Aspergillus flavus, Beauveria bassiana, and Metarhizium anisopliae demonstrated a detection sensitivity that was at least three orders of magnitude greater than that of conventional methods. In contrast, the non-chitinolytic fungi Penicillium notatum and Fusarium venenatum presented no detectable fluorescent signals. This fluorogenic medium provides a rapid, cost-effective, and highly sensitive tool for screening chitinolytic microorganisms with potential applications in agriculture, veterinary parasitology, and environmental microbiology. Full article

Trichoderma aggressivum f. aggressivum is a major pathogen responsible for the green mould disease in Agaricus bisporus, causing significant yield losses. This study evaluated the effects of native bacterial strains as biocontrol agents against T. aggressivum f. aggressivum in the cultivation of Agaricus bisporus. Bacterial strains were collected from mushroom caps and screened for plant growth-promoting traits, including siderophore production, phosphate solubilisation, indole-3-acetic acid synthesis, chitinolytic, and proteolytic activities. In vitro antagonism assays identified Pseudomonas chlororaphis (Pl 4/2), Bacillus wiedmannii (Pl 6/1), and Bacillus cereus (Pl 5/2) as the most promising candidates. In vivo assays under controlled compost conditions revealed that Pl 5/2 significantly enhanced mycelial growth in A. bisporus. Field trials have confirmed its strong biocontrol potential, with disease severity reductions comparable to the fungicide Prochloraz. Furthermore, Pl 5/2 markedly increased the mushroom yield and the improved cap number and weight in A. bisporus. These results demonstrate the dual functionality of B. cereus Pl 5/2 in suppressing green mould and promoting yield, supporting its potential integration into sustainable, chemical-free mushroom production systems. Full article

Chitinolytic activity is a well-documented phenotype controlled by quorum sensing (QS) in Chromobacterium strains but also regulated by carbon catabolite repression mechanisms. This work comprehensively reviews scientific literature on chitinolytic activity, reinforcing the need to use a minimal culture medium supplemented with chitin for assays testing chitinolytic activity modulated by QS in Chromobacterium strains. Full article

Fusarium culmorum is the causal agent of root rot and crown rot in soft wheat. The aim of this study was to investigate the control mechanism of Talaromyces pinophilus HD25G2 as a biocontrol agent against F. culmorum. This involved the isolation and molecular identification of Fusarium and Talaromyces strains from soft wheat. The assay included the inhibition test of F. culmorum mycelial growth on potato dextrose agar and soft wheat media at two water activity values (0.98 and 0.95), its production of mycotoxins, and the fungal cell wall-degrading enzymes implicated in the antagonistic effect of T. pinophilus. The results showed that T. pinophilus and its extract free of cells reduced the growth of F. culmorum by over 55%. Interestingly, the T. pinophilus HD25G2 showed high chitinase, protease, and cellulose production on solid media. In addition, chitinolytic and proteolytic activities were estimated at the values of 1.72 ± 0.02UI and 0.49 ± 0.01UI, respectively. However, the mycotoxin evaluation assay revealed that F. culmorum HD15C10 produced zearalenone (ZEA) and the biocontrol agent enhanced its production, but the early inoculation of T. pinophilus, before F. culmorum growth onset, inhibited 100% its growth and, therefore, prevented the presence of ZEA. Hence, this strain can be proposed as a biocontrol agent against F. culmorum, and it can be further investigated for biocontrol of Fusarium root and crown rot in vivo. Full article

Moniliophthora roreri (MR, frosty pod rot) and M. perniciosa (MP, witches’ broom disease) pose critical threats to cacao production in Latin America. This study explores the biocontrol potential of Trichoderma spp. strains against these pathogens through exploratory analysis of mycoparasitism, chitinolytic activity, and volatile organic compound (VOC) production. Dual-culture assays revealed species-specific antagonism, but C2A/C4B showed a dual-pathogen efficacy (>93% of Monioliopthora inhibition). Chitinase activity revealed C4A/C1 strains as exceptional producers (72 mg/mL NAGA vs. MR and 94 mg/mL vs. MP, respectively). GC-MS analysis identified pathogen-modulated VOC dynamics: hexadecanoic acid dominated in 80% Trichoderma solo-cultures (up to 26.65% peak area in C3B). MP showed 18.4-fold higher abundance of hexadecanoic acid than MR (0.23%). In 90% of dual-culture with MR and MP, HDA was detected as the most abundant. Functional specialization was evident. C4A and C1 prioritized chitinase production growing on MR and MP cell walls (respectively), whereas C9 excelled in antifungal hexadecanoic acid synthesis in confrontation with both pathogens. Complementary strengths among strains—enzymatic activity in C4A/C4B versus volatile-mediated inhibition in C9—suggest niche partitioning, supporting a consortium-based approach for robust biocontrol. This study provides preliminary evidence for the biocontrol potential of several Trichoderma strains, showing possible complementary modes of action. Full article

Peach fruit faces severe postharvest losses due to thin epidermis and susceptibility to Rhizopus stolonifer-induced soft rot. Chemical control risks residue and resistance issues, demanding eco-friendly alternatives. This study elucidated the mechanism by which trans-2-hexenal (E2H) mitigated postharvest soft rot caused by Rhizopus stolonifer in peach (Prunus persica cv. Hujing Milu) fruit. The results demonstrated that E2H treatment significantly delayed lesion expansion by 44.7% and disease incidence by 23.9% while effectively maintaining fruit quality by delaying firmness loss, reducing juice leakage, and suppressing malondialdehyde (MDA) accumulation. E2H treatment upregulated phenylpropanoid pathway gene expression, enhancing key phenylpropanoid metabolism enzymes activities (phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), polyphenol oxidase (PPO), peroxidase (POD)), leading to the increase of total phenolics by 7.9%. E2H treatment analysis revealed significant enhancements in both chitinolytic activity (CHI) and β-1,3-glucanase (GLU) activity by 85.7% and 12.9%, indicating potentiation of the enzymatic defense system. Concurrently, E2H treatment could improve the redox modulation capacity of peach fruits through promoting catalytic efficiency of redox-regulating enzymes, increasing the accumulation of ascorbic acid (AsA) by 8.1%, inhibiting the synthesis of dehydroascorbic acid (DHA) by 18.6%, as well as suppressing the biosynthesis of reactive oxygen species (ROS). These coordinated enhancements in pathogenesis-related proteins (CHI, GLU), phenylpropanoid metabolism activation, and antioxidant systems are strongly associated with E2H-induced resistance against Rhizopus stolonifer, though contributions from other factors may also be involved. Full article

The depolymerization of chitosan using chitinolytic enzymes is one of the most promising approaches for the production of bioactive soluble chitooligosaccharides (COS) due to its high specificity, environmental safety, mild reaction conditions, and potential for development. However, the comparative efficacy of bacterial chitinases and chitosanases in terms of yield, solubility, and antimicrobial activity of produced COS remains understudied. In this work, chitinase (73 kDa) and chitosanase (40 kDa) from the strain Bacillus thuringiensis B-387 (Bt-387) were purified using various chromatographic techniques and compared by their action on chitosan (DD 85%). The molecular mass and structure of generated COS was determined using TLC, LC-ESI-MS, HP-SEC, and C¹³-NMR techniques. Chitosanase converted the polymer more rapidly to short COS (GlcN₂-GlcN₄), than chitinase, and was more specific in its action on mixed bonds between GlcN and GlcNAc. Chitosanase needed a noticeably shorter incubation time and enzyme–substrate ratio than chitinase for production of larger oligomeric molecules (Mw 2.4–66.5 and 15.4–77.7 kDa, respectively) during controlled depolymerization of chitosan. Moreover, chitosanase-generated oligomers demonstrate better solubility and a higher antifungal activity in vitro against the tested plant pathogenic fungi. These features, as well as the high enzyme production and its simplified purification protocol, make chitosanase B-387 more suitable for the production of antifungal chitooligomers than chitinase. Full article

This study aimed to investigate the biocontrol activity of rhizosphere isolates against late blight disease of tomatoes caused by the fungus Phytophthora infestans. A total of 30 rhizospheric bacterial isolates were evaluated for their antagonistic activity against P. infestans in vitro and in vivo. The results demonstrated that among the 30 isolates tested, six (RS65, RP6, RS47, RS46, RP2, and RS61) exhibited a highly significant inhibitory effect (p < 0.001) on the mycelial growth of P. infestans in vitro, with the inhibition rate exceeding 67%. Among the isolates, RS65 exhibited the highest inhibition rate at 78.48%. For antagonistic mechanisms, the results demonstrated that the six isolates exhibited significant enzymatic activity, including proteolytic, lipolytic, and chitinolytic activity, as well as the production of HCN, cellulase, and pectinase. Isolate RS65, which showed the highest inhibition rate, was further evaluated under greenhouse conditions. This investigation revealed significant differences in the severity of late blight between the control and the RS65 treatment. The control showed a severity level of 31.26%, whereas the RS65 treatment achieved the lowest severity of 16.54%. Molecular identification results indicated that the RS65 isolate (accession numbers PV208381) is a Bacillus genus with 99% proximity to Bacillus velezensis. This finding suggests that the Bacillus RS65 treatment could provide effective protection against P. infestans infection in tomato plants. These findings highlight the potential of Bacillus RS65 as a biocontrol agent in integrated disease management for tomato late blight. Full article

The conventional methods used to produce N-acetyl-β-D-glucosamine (GlcNAc) from seafood waste require pretreatment steps that use acids or bases to achieve the extraction and decrystallization of chitin prior to enzymatic conversion. The development of an enzymatic conversion method that does not require the pretreatment of seafood waste is essential for the efficient and clean production of GlcNAc. In this study, the annotated metagenomic assembly data of domesticated microbiota (XHQ10) were analyzed to identify carbohydrate-active enzymes (CAZymes), and an in-depth analysis of the high-quality genome FS13.1, which was obtained from metagenomic binning, was performed; this enabled us to elucidate the catabolic mechanism of XHQ10 by using shrimp shell chitin as a carbon and nitrogen source. The only β-N-acetylglucosaminidase (named XmGlcNAcase) was cloned from FS13.1 and biochemically characterized. The direct production of GlcNAc from shrimp shell powder (SSP) via the use of a chitin enzyme cocktail was evaluated. Under the action of a chitin enzyme cocktail containing 5% recombinant XmGlcNAcase and a crude XHQ10 enzyme solution, the yield and purity of the final conversion of SSP to GlcNAc were 2.57 g/L and 82%, respectively. This is the first time that metagene-derived GlcNAcase has been utilized to achieve the enzymatic conversion of untreated seafood waste, laying the foundation for the low-cost and sustainable production of GlcNAc. Full article

Living systems cannot rely on random intermolecular approaches toward cell crowding, and hidden mechanisms must be present to favor only those molecular interactions required explicitly by the biological function. Electromagnetic messaging among proteins is proposed from the observation that charged amino acids located on the protein surface are mostly in adjacent sequence positions and/or in spatial proximity. Molecular dynamics (MD) simulations have been used to predict electric charge proximities arising from concerted motions of charged amino acid side chains in two protein model systems, human ubiquitin and the chitinolytic enzyme from Ostrinia furnacalis. This choice has been made for their large difference in size and sociality. Protein electrodynamics seems to emerge as the framework for a deeper understanding of the long-distance interactions of proteins with their molecular environment. Our findings will be valuable in orienting the design of proteins with specific recognition patterns. Full article

The Asian dung beetle (Catharsius molossus L.; Coleoptera: Scarabeidae) has been shown to positively affect soil bacterial diversity and the agronomic features of crop plants. In this study, we used bioinformatic tools to investigate the differences in bacterial functional phenotypes and ecological functions between control soil, cow dung-amended soil (CD), and cow dung-amended soil composted by dung beetles (DB). The soil bacterial metagenomes were sequenced and analyzed with the bioinformatic packages BugBase, PICRUSt2, Tax4Fun, and FAPROTAX to evaluate the effects of dung beetle-mediated composting on bacterial functions such as human and plant pathogenicity, trophic strategies, and soil nutrient transformation. BugBase proved useful for the determination of differences in major functional phenotypes, whereas FAPROTAX was effective at identifying differences in bacterial ecological functions between the treatments. Both tools suggested a relative decrease in human pathogens in the DB soil. This was corroborated by the pairwise comparison of abundances in bacterial species, which showed a significant reduction in the abundance of the broad-host-range pathogen Pseudomonas aeruginosa in the DB soil. In addition, FAPROTAX suggested a decrease in plant pathogens and an increase in chitinolytic bacteria, meaning that the DB treatment might be beneficial to the plant-growth-promoting bacteria involved in biological control. Finally, FAPROTAX revealed an array of ecological functions related to trophic strategies and macro- and micronutrient metabolism. According to these results, the activity of C. molossus beetles enhanced methanotrophy, ammonification, nitrification, sulfate reduction, and manganese oxidation, whereas iron respiration was decreased in the DB-treated soil. Our results represent a collection of general insights into the effects of C. molossus beetles on soil bacterial functions, which also reflect on the nutrient composition of dung beetle-composted soil. Full article

Chitin is the second most prevalent polysaccharide found in nature, following cellulose. Amino-oligosaccharides, the byproducts of chitin degradation, exhibit favorable biological properties and potential for various uses. Chitinases play a crucial function in the breakdown of chitin, and their exceptionally effective production has garnered significant interest. Here, in this study, the exochitinase PbChiA, obtained from Paenibacillus barengoltzii, was recombinantly produced and immobilized using the CotG surface protein of Bacillus subtilis WB800N. The resulting strain Bacillus subtilis WB800N pHS-CotG-Chi exhibited exceptional heat stability and efficacy across various pH levels. The chitinolytic activity of the enzyme, which had been isolated and immobilized on the spore surface, was measured to be approximately 16.06 U/mL. Including Ni²⁺, Zn⁺², and K⁺, and EDTA at various concentration levels in the reaction system, has significantly enhanced the activity of the immobilized enzyme. The immobilized exochitinase demonstrated a notable rate of recycling, as the recombinant spores sustained a relative enzyme activity of more than 70% after three cycles and 62.7% after four cycles. These findings established a basis for additional investigation into the role and practical use of the immobilized bacterial exochitinase in industry. Full article