Biotechnology Bulletin ›› 2023, Vol. 39 ›› Issue (3): 267-277.doi: 10.13560/j.cnki.biotech.bull.1985.2022-0722

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Isolation, Identification and Bio-activity of Three Bacillus Strains with Biocontrol Function

SHEN Yun-xin1,2(), SHI Zhu-feng2, ZHOU Xu-dong1,2, LI Ming-gang3, ZHANG Qing2, FENG Lu-yao2, CHEN Qi-bin1, YANG Pei-wen2()   

  1. 1. College of Plant Protection, Yunnan Agricultural University, Kunming 650201
    2. Institute of Agricultural Environment and Resources, Yunnan Academy of Agricultural Sciences, Kunming 650205
    3. Yunnan Institute of Microbiology, Kunming 650091
  • Received:2022-06-15 Online:2023-03-26 Published:2023-04-10

Abstract:

Based on healthy tobacco rhizosphere soil, bacterial strains with diverse functions and high activity were isolated and screened to provide efficient and diversified biocontrol resources for the biological control of crop diseases. The plate confrontation method was used to screen the strains with high activity and wide antibacterial spectrum, and the inhibition rate of the strains on Fusarium oxysporum, mycelia growth and spore germination rate were determined. PCR was adapted to detect the antibiotic synthesis genes of the strains, and the control effects of the functional strains on tomato fusarium wilt were detected by indoor pot experiments. The enzyme production, phosphorus and potassium solubilization, nitrogen fixation and siderophorer production abilities of the functional strains were measured in vitro. The functional strains were identified by combining morphological, physiological and biochemical and 16S rDNA universal primers. A total of 127 strains were isolated from the rhizosphere soil of tobacco, and 24 strains presented the inhibitory effects on Fusarium oxysporum sp. of tomato. The inhibitory rates of 3 top-activity strain SH-1471, SH-1464 and SH-1439 against F. oxysporum sp. of tomato were 82.0%, 74.0% and 75.0%, respectively. It caused the mycelia distortion of F. oxysporum sp. of tomato and vesicle structure was formed, and thus inhibited the spore germination of F. oxysporum sp. of tomato by 62.7%, 50.0% and 37.0%, respectively. The three functional strains had genes for antibiotic synthesis, including srfA, fenB, ituA, ituD and bymA. The results of pot experiment showed that SH-1471, SH-1464 and SH-1439 had 83.7%, 60.7% and 59.0% control effect against tomato fusarium wilt. In addition, the three strains all had the ability of producing protease and cellulase, solubilizing phosphorus, fixing nitrogen, and secreting siderophores. The SH-1471 was identified as Bacillus amyloliquefaciens(Gen-bank ON417363), and SH-1464 as Bacillus paramycoides(Gen-bank ON417365)and SH-1439 as Bacillus siamensis(Gen-bank ON417364). Strains SH-1471, SH-1464 and SH-1439 have high-efficiency and broad-spectrum antibacterial ability and diversified functions, and they may be used as efficient biocontrol resources for a variety of diseases and had great development potential.

Key words: tobacco rhizosphere soil, biocontrol strain, tomato fusarium wilt, study on control effect