Aug 2026· Microorganisms· Vol 14· 0 citations· 33 references
Medicine
TL;DR
Overall, UzMU25 exhibited preliminary enzymatic, antagonistic, and biofilm-forming characteristics of biotechnological interest, but whole-genome antimicrobial-resistance screening and more comprehensive phenotypic and toxicological evaluations are required before the strain can be recommended for probiotic or other practical applications.
Abstract
Endophytic bacteria associated with medicinal plants represent a potential source of microorganisms with useful enzymatic and antagonistic properties. In this study, 14 bacterial isolates were recovered from the leaves, roots, flowers, and petioles of Inula helenium and screened for morphological, biochemical, and hydrolytic characteristics. Isolate IH-B3, which showed the most pronounced starch- and casein-hydrolysis zones during preliminary screening, was selected for further characterization. MALDI-TOF mass spectrometry assigned the isolate to Bacillus subtilis with an identification score of 2.26, and the strain was designated B. subtilis UzMU25. Its 1444 bp 16S rRNA gene sequence was deposited in GenBank under accession number PZ593820. The strain was catalase- and lecithinase-positive but gelatinase- and hemolysis-negative, and it grew at pH 6.5 and in the presence of horse bile under the qualitative assay conditions used. Hydrolysis-zone diameters ranged from 46 to 52 mm for amylase, 34 to 42 mm for protease, and 10 to 16 mm for lipase activity. In direct antagonism assays, UzMU25 inhibited all six bacterial and fungal test organisms, producing inhibition zones of 26–36 mm. Biofilm biomass varied with incubation time and reached its highest corrected OD590 value at 12 h (0.780 ± 0.025). Antibiotic-disc testing showed a 10 mm inhibition zone for vancomycin, indicating reduced susceptibility under the applied conditions and requiring further investigation of its genetic basis and potential transferability. No mortality was observed during the preliminary acute oral study following administration of the tested preparation at doses up to 10,000 mg kg−1, and no visible dermal or conjunctival irritation was detected. Overall, UzMU25 exhibited preliminary enzymatic, antagonistic, and biofilm-forming characteristics of biotechnological interest. However, whole-genome antimicrobial-resistance screening and more comprehensive phenotypic and toxicological evaluations are required before the strain can be recommended for probiotic or other practical applications.
The isolate showed promising probiotic characteristics, maintaining viability under acidic conditions (pH 2), bile salts, and phenol, and the absence of hemolytic activity and significant biofilm formation further supports its candidacy as a safe probiotic.
Mohammed Ayaz, M. Sarkar, Mohammad Monerul Islam et al.· Archives of Microbiology· 0 citations
Endophytic bacteria represent a promising, sustainable alternative to synthetic agrochemicals for plant disease management by actively antagonizing phytopathogens and stimulating host immune responses. Despite its traditional use as an antimicrobial remedy, Wedelia chinensis remains underexplored as a source of beneficial endophytes. This study aimed to isolate and screen endophytic bacteria from W. chinensis for their antifungal activity against Fusarium oxysporum. Among 14 endophytic isolates, Bacillus subtilis LS1-5 showed the strongest antifungal activity by dual culture assay. Its cell-free culture filtrate effectively inhibited fungal spore germination by 91.3% at a 20% concentration. Crucially, B. subtilis LS1-5 produced several extracellular enzymes, including cellulase, amylase, chitinase, pectinase, gelatinase, lipase, and protease. Furthermore, the LS1-5 strain exhibited a broad array of plant growth-promoting and environmental resilience traits. Notably, it synthesized indole-3-acetic acid (IAA) at 2.11 ± 0.27 µg/mL in an LB medium without L-tryptophan, significantly promoted a 34.19% increase in root elongation, and demonstrated remarkable tolerance to extreme conditions, including high salinity (11% NaCl) and broad pH levels ranging from 6 to 12. Additionally, volatile organic compounds (VOCs) emitted by LS1-5 significantly inhibited the severe bacterial pathogens Xanthomonas oryzae (45.83%) and Xanthomonas citri (47.99%). These findings highlight B. subtilis LS1-5 as a highly effective candidate for biological control and sustainable agricultural applications.
D. Nguyen, Dong Tang Vien, Ngoc-Minh Truong Bui et al.· IOP Conference Series: Earth...· 0 citations
Aim: The study aimed at studying, identifying, and evaluating the bioactive properties of endophytic bacteria isolated from the medicinal plant Dillenia pentagyna Roxb.
Methods: An agar well diffusion assay was employed for antimicrobial screening. 16S rRNA gene sequencing was done to identify selected bacteria. Antioxidant assays using DPPH and ABTS radical scavenging assays were performed. Cytotoxicity was tested using the MTT assay, and detection of secondary metabolites was done using HPTLC.
Results: Among the 96 isolates, one endophytic bacterium, BPSL8, identified as Bacillus pumilus, had the most significant activity. The crude methanol extract of BPSL8 exhibited antibacterial activity against Micrococcus luteus, Bacillus subtilis, and Klebsiella pneumoniae. BPSL8 has a potent antioxidant capacity of DPPH and ABTS free radicals with an IC₅₀ of 6.29 and 4.25 µg/mL, respectively. BPSL8 was found to have cytotoxicity against HT29 (IC50 55.2 µg/mL) and HeLa (IC50 51.9 µg/mL). HPTLC analysis done for three fractions (DCM, EA, and MeOH) of BPSL8 detected the presence of phytochemicals.
Conclusion: This study demonstrates the potential of the identified endophytic bacterium B. pumilus as a source of as a potent antibacterial, antioxidant, and anticancer agent with a key role in providing insights into their impact on the host as well as their applications in the field of pharmaceuticals.
L. Sangi, W. Carrie, Lalhruaitluanga Hauhnar et al.· Journal of Biological Resear...· 0 citations
Hydrolytic enzymes produced by bacteria have broad potential for substrate degradation and industrial processing. This study isolated, identified, and screened culturable bacteria from common bean (Phaseolus vulgaris L.) rhizospheric soil in Akungba-Akoko for amylase and protease production. Isolates were characterised using cultural, morphological, and biochemical tests, and their identities were determined by comparison with standard bacteriological descriptions. Amylolytic and proteolytic activities were screened on media containing 1% soluble starch or skim milk, respectively. Clear-zone formation indicated a positive reaction, and hydrolytic indices were calculated from the diameters of the clearance zones and colonies. Positive isolates were further evaluated by quantitative enzyme assays using the dinitrosalicylic acid method. Seventeen bacterial isolates representing nine genera were identified. Bacillus megaterium (D40) showed the highest amylolytic index (3.61) and amylase activity (5.45±0.14 U/mL). Pseudomonas sp. (B20) showed the highest proteolytic index (3.38) and protease activity (1.19±0.02 U/mL). Actinobacillus sp. (D42) had the lowest amylolytic index (0.08), whereas Streptococcus sp. (C40) had the lowest proteolytic index (0.29). Several isolates showed no detectable activity for one or both enzymes. The findings demonstrate that bean rhizospheric soil contains culturable bacteria with variable amylolytic and proteolytic potential. These isolates may provide candidate sources for subsequent optimisation and characterisation of microbial enzymes intended for industrial applications.
O. R. Adeoyo· Asian Journal of Biotechnolo...· 0 citations
The integrated experimental and in silico approach highlights soil-derived actinomycetes as versatile and sustainable bioresources with significant pharmaceutical and biotechnological potential, emphasizing their role in combating antimicrobial resistance and enabling the rational development of novel therapeutic and industrial products.
Meghana Arivilu, Shaziya Sulthana, Vijay Ramesh et al.· Journal of Pure and Applied...· 0 citations
The rise of antimicrobial resistance and emerging infectious diseases necessitates the discovery of novel antibacterial agents. Endophytic actinomycetes, especially Streptomyces species colonizing medicinal plant tissues, constitute a reservoir of structurally diverse bioactive metabolites that remains insufficiently characterized. This study reports the isolation and comprehensive characterization of an endophytic actinomycete, designated strain YBRX0, recovered from the root tissues of the Vietnamese medicinal plant Croton tonkinensis Gagnep. Strain identity was established through an integrated approach combining colony morphology, scanning electron microscopy, physiological and biochemical profiling, and 16S rRNA gene phylogenetic analysis. Bioactivity screening of the ethyl acetate fermentation extract employed agar well diffusion to assess antibacterial spectrum, with inhibitory potency quantified by broth microdilution. Antioxidant capacity was measured via DPPH radical scavenging, and secondary metabolite composition was profiled by GC–MS. The integrated characterization placed strain YBRX0 unambiguously within the genus. At 1 mg/mL, the ethyl acetate extract demonstrated broad-spectrum activity against both Gram-positive and Gram-negative pathogens, with MIC values ranging from 8 to 16 μg/mL. Antioxidant screening yielded an IC₅₀ of 197.26 ± 8.87 μg/mL. GC–MS tentatively identified Pyrrolopyrazine diketopiperazines and Benzeneacetamide as principal constituents. Collectively, these findings indicate that the crude extract of Streptomyces sp. YBRX0 exhibited notable antibacterial activity despite being an unfractionated mixture, supporting its potential as a promising source of bioactive metabolites for further bioprospecting and compound isolation efforts targeting drug-resistant pathogens.
Hà Trang Phan, Hung Vuong Pham, Xuan Truong Nguyen et al.· Journal of Genetic Engineeri...· 0 citations
