JOURNAL OF MICROBIOLOGY
·
2013
·Vol. 51
·期 2
·166-173
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IF 1.276
Wu Qiong,Bai Linquan,Liu Weicheng,Li Yingying,Lu Caige,Li Yaqian,Fu Kehe,Yu Chuanjin,Chen Jie
Streptomyces lydicus A01 and Trichoderma harzianum P1 are potential biocontrol agents of fungal diseases in plants. S. lydicus A01 produces natamycin to bind the ergosterol of the fungal cell membrane and inhibits the growth of Botrytis cinerea. T. harzianum P1, on the other hand, features high chitinase activity and decomposes the chitin in the cell wall of B. cinerea . To obtain the synergistic biocontrol effects of chitinase and natamycin on Botrytis cinerea , this study transformed the chit42 gene from T. harzianum P1 to S. lydicus A01. The conjugal transformant (CT) of S. lydicus A01 with the chit42 gene was detected using polymerase chain reaction (PCR). Associated chitinase activity and natamycin production were examined using the 3, 5-dinitrosalicylic acid (DNS) method and ultraviolet spectrophotometry, respectively. The S. lydicus A01- chit42 CT showed substantially higher chitinase activity and natamycin production than its wild type strain (WT). Consequently, the biocontrol effects of S. lydicus A01- chit42 CT on B. cinerea , including inhibition to spore germination and mycelial growth, were highly improved compared with those of the WT. Our research indicates that the biocontrol effect of Streptomyces can be highly improved by transforming the exogenous resistance gene, i.e. chit42 from Trichoderma , which not only enhances the production of antibiotics, but also provides a supplementary function by degrading the cell walls of the pathogens.
研究领域:
微生物学
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植物病理学
·
基因工程
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PROCESS BIOCHEMISTRY
·
2024
·
IF 3.7
Chuang Li,Xian Zhang,Yuqing Wang,Qingtao Liu,Zhou Wang,Rui Huang,Zhenglian Xue
To enrich ‘epoxide hydrolase (EH) tool cabinet’ for preparing enantiopure epoxides and 1,2-diols, a novel microbial EH, Sf EH2, was identified from Streptomyces fradiae SF-2. Bioinformatics analysis indicated that Sf EH2 has typical structural characteristics of α/β-hydrolase fold superfamily. Its coding gene, sfeh 2, was then codon-optimized and amplified. A recombinant (re) Sf EH2-expressing E. coli BL21(DE3) strain ( E. coli / sfeh 2) was constructed through DNA manipulations. Substrate spectrum assay including fifteen common racemic ( rac -) epoxides by E. coli / sfeh 2 showed that re Sf EH2 displayed the highest and best complementary regioselectivities (regioselectivity coefficients, α R = 89.7% and β S = 91.4%) towards rac - 14a , as well as the highest enantioselectivity (enantiomeric ratio, E = 15.3) in S -type towards rac - 15a . Molecular docking simulation revealed that Sf EH2 preferentially attacked C α of ( R )- 14a and C β of ( S )- 14a geometrically. In kinetic parameter analysis, the K m R (5.74 mM) of purified re Sf EH2 for ( R )- 15a was 1.76-fold lower than K m S (10.09 mM) for ( S )- 15a . At last, using 50 mg dry cell weight/mL E. coli / sfeh 2, the scale-up enantioconvergent hydrolysis of 100 mM rac - 14a at 30 °C for 6.0 h afforded ( S )- 14b with 80.9% ee p and 90.1% yield, while the kinetic resolution of 150 mM rac - 15a retained ( S )- 15a with >99.0% ee s and 42.2% yield.
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Fermentation-Basel
·
2023
·Vol. 9
·期 10
·866
·
IF 3.7
Chenbo Jia,Xian Ma,Yuting Jiang,Shanshan Cheng,Sijun Yue,Jianyu Su
Streptomyces fradiaesf106 is a type of actinomycete that can produce abundant secondary metabolites, making it a natural cell factory for drug synthesis. In order to comprehensively understand the genomic profile ofStreptomyces fradiaesf106 and its potential for producing secondary metabolites, a combination of several methods was used to perform whole-genome sequencing of sf106. The results showed that sf106 is most closely related toStreptomyces xinghaiensisS187; the average nucleotide identity and average amino acid identity of sf106 and S187 were more than 96%. The genome size of sf106 is approximately 7300 kb, the GC content is greater than 72%, and more than 6700 coding sequences (CDS) were identified. Analysis of mobile genetic elements revealed the presence of a large number of horizontally transferred genes inStreptomyces fradiaesf106, which contribute to microbial diversity. Through antiSMASH prediction, 22 secondary metabolite gene clusters were obtained, which had great potential to generate polyketide metabolites. By examining the data, it was found that the genes contained in cluster 9 were similar to those involved in tylosin synthesis. Non-targeted metabolome sequencing revealed that a total of 1855 identifiable metabolites were produced in the fermentation broth, and the majority of metabolites showed highly significant differences in mean relative abundance between the groups. The identified metabolites were compared against the KEGG compound database to obtain metabolite classifications, mainly including Biological Roles, Phytochemical Compounds, Lipids, and Pesticides. One-way ANOVA indicated that the relative concentration of tylosin differed significantly across all the growth periods, except for the late-logarithmic and stabilization stages. This study provides important basic information on the secondary metabolite research of sf106, which will help us to understand and applyStreptomyces fradiaesf106 more comprehensively.Keywords:Streptomyces;whole genome;non-targeted metabolome;secondary metabolites;tylosin
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FOOD CHEMISTRY
·
2025
·
IF 9.8
Zhuoning Cao,Chengqiang Li,Hong Jiang,Francesco Secundo,Xiangzhao Mao
β- N -acetylhexosaminidases garnered attention in the enzymatic synthesis of lacto- N -triose II (LNT2) as the backbone precursor of human milk oligosaccharides (HMOs). In this study, β- N -acetylglucosaminidases Hex(Sv)-2557 from Streptomyces violascens ATCC 27968 was engineered based on a stabilizing intermediate strategy to improve its transglycosylation activity for LNT2 synthesis. A mutant Hex(Sv)-2557(D297K) with a transglycosylation activity of 38.4 U/mg with p NP-GlcNAc −1.9-fold higher than that of Hex(Sv)-2557– was obtained and characterized. Instead, the hydrolase activity of the mutant was 73 % lower compared to the wild-type enzyme. Importantly, the mutant can use N -acetyl chitobiose (GlcNAc 2 ) as the donor for LNT2 synthesis. The LNT2 yield of 14.85 % was obtained when the synthetic reaction, catalyzed by the mutant Hex(Sv)-2557(D297K), started from whey powder and GlcNAc 2 -prepared from chitin by chitinase ChiA and ChiB. This study has altered the donor for the action by directed modification and promoting the high-value utilization of whey powder and chitin.
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MICROBIAL PATHOGENESIS
·
2025
·
IF 3.5
Rewan Abdelaziz,Alshimaa A. Khalil,Rania Ali,Mohamed Taha Yassin,Fatimah Olyan Al-Otibi,Mohamed Ragab AbdelGawwad,Shaimaa A.A. Ahmed
The present study investigated the antibacterial efficacy of telomycin nanoparticles (TNPs). Telomycin, a bioactive metabolite of Streptomyces abietis PP752347, was loaded onto chitosan nanoparticles. The minimum inhibitory concentration (MIC 50 ) of telomycin against pathogenic strains of Staphylococcus aureus was determined to be 1.0 ± 1.00 μg/mL and 2.0 ± 1.00 μg/mL, respectively, against different strains. Meanwhile, the (MIC 50 ) of TNPS against the same strains was .125 ± 1.00 μg/mL and 1.0 ± 1.00 μg/mL, respectively. Morphological changes in S. aureus treated with TNPS were examined using scanning electron microscopy (SEM). Additionally, the bioactive metabolite extracts were characterized using X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR), while SEM was employed to characterize the nanoparticles. For the in vivo experiment, 120 African catfish ( Clarias gariepinus ) were divided into four groups: the first group served as the negative control (neither challenged nor treated); the second group (TNPS) received TNPS treatment (100 μg/L); the third group (SA) represented the positive control, infected with S. aureus ; and the fourth group (SA + TNPS) was infected with S. aureus and treated with TNPS. Infected fish (SA and SA + TNPS groups) received an intraperitoneal injection of S. aureus (1.6 × 10 6 CFU/mL). The findings demonstrated that all infected groups exhibited noticeable clinical signs resulting from S. aureus infection. TNPS administration via immersion significantly reduced the negative impacts of infection on liver and kidney biomarkers, innate immune responses, antioxidant levels, serum gonadotropic hormones, and hepatic expression levels of both Caspase-3 and TNF-α. TNPS treatment significantly ( p < 0.05) alleviated S. aureus –induced clinical symptoms and hepatorenal dysfunction. It enhanced innate immunity (lysozyme, nitric oxide, MPO, and IL-1β expression), antioxidant capacity, and sex hormone levels, while reversing histopathological alterations in the liver, kidney, spleen, and ovaries. Furthermore, TNPs reduced hepatic expression of both Caspase-3 and TNF-α. These findings indicate that TNPs (100 μg/L) is safe for African catfish and exhibits potent antibacterial activity, supporting its potential as a promising and eco-friendly therapeutic agent for aquaculture.
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Microorganisms
·
2020
·Vol. 8
·期 3
·319
·
IF 4.152
Xuewei Li,Beibei Li,Shurui Cai,Yu Zhang,Mingjie Xu,Chunmei Zhang,Bo Yuan,Ke Xing,Sheng Qin
Black spot disease, which is caused by the pathogenic fungalCeratocystis fimbriata, seriously affects the production of sweet potato and its quality during postharvest storage. In this study, the preliminary identification of the rhizosphere actinomycete strain SPS-33, and its antifungal activity of volatilesin vitroandin vivowas investigated. Based on morphological identification and phylogenetic analysis of the 16S rRNA gene sequence, strain SPS-33 was identified asStreptomyces lavendulae.Volatile organic compounds (VOCs) emitted by SPS-33 inhibited mycelial growth and sporulation ofC. fimbriatain vitroand also induced a series of observable hyphae morphological changes. In anin vivopathogenicity assay, exposure to SPS-33 significantly decreased the lesion diameter and water loss rate in sweet potato tuberous roots (TRs) inoculated withC. fimbriata. It increased the antioxidant enzymes’ activities of peroxidase, catalase, and superoxide dismutase as well as decreased malondialdehyde and increased total soluble sugar. In the VOC profile of SPS-33 detected by a headspace solid-phase micro extraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS), heptadecane, tetradecane, and 3-methyl-1-butanol were the most abundant compounds. 2-Methyl-1-butanol, 3-methyl-1-butanol, pyridine, and phenylethyl alcohol showed strong antifungal effects againstC. fimbriata. These findings suggest that VOCs fromS. lavendulaeSPS-33 have the potential for pathogenC. fimbriatacontrol in sweet potato postharvest storage by fumigant action.Keywords:Ipomoea batatas(L.) Lam.;Streptomyces lavendulae;volatile organic compound;fumigant;antimicrobial
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