Control of postharvest soft rot caused by Erwinia carotovora of vegetables by a strain of Bacillus amyloliquefaciens and its potential modes of action
Erwinia carotovora subsp. carotovora (Ecc), the causal agent of bacterial soft rot, is one of the destructive pathogens of postharvest vegetables. In this study, a bacterial isolate (BGP20) from the vegetable farm soil showed strong antagonistic activity against Ecc in vitro, and its twofold cell-free culture filtrate showed excellent biocontrol effect in controlling the postharvest bacterial soft rot of potatoes at 25 °C. The anti-Ecc metabolites produced by the isolate BGP20 had a high resistance to high temperature, UV-light and protease K. Based on the colonial morphology, cellular morphology, sporulation, and partial nucleotide sequences of 16S rRNA and gyrB gene, the isolate BGP20 was identified as Bacillus amyloliquefaciens subsp. plantarum. Further in vivo assays showed that the BGP20 cell culture was more effective in controlling the postharvest bacterial soft rot of green peppers and Chinese cabbages than its twofold cell-free culture filtrate. In contrast, the biocontrol effect and safety of the BGP20 cell culture were very poor on potatoes. In the wounds of potatoes treated with both the antagonist BGP20 and the pathogen Ecc, the viable count of Ecc was 31,746 times that of BGP20 at 48 h of incubation at 25 °C. But in the wounds of green peppers, the viable count of BGP20 increased 182.3 times within 48 h, and that of Ecc increased only 51.3 %. In addition, the treatment with both BGP20 and Ecc induced higher activity of phenylalanine ammonia-lyase (PAL) than others in potatoes. But the same treatment did not induce an increase of PAL activity in green peppers. In conclusion, the present study demonstrated that the isolate BGP20 is a promising candidate in biological control of postharvest bacterial soft rot of vegetables, but its main mode of action is different among various vegetables.
KeywordsPostharvest bacterial diseases Erwinia carotovora subsp. carotovora Bacillus amyloliquefaciens subsp. plantarum Biological control Mode of action
We are very grateful to Jia-Qin Fan (Nanjing Agricultural University) for kindly providing the pathogen Erwinia carotovora subsp. carotovora. This work was supported by the Post-Doctoral Fund of Jiangsu Province, China.
- Food and Drug Administration (1999) Code of Federal Regulations, Title 21: Food and Drugs, Chapter 1: Food and Drug Administration Department of Health and Human Services, Part 184: direct food substances affirmed as generally recognized as safe. US Government Printing Office, Washington, DCGoogle Scholar
- Liao CH (2009) Control of foodborne pathogens and soft-rot bacteria on bell pepper by three strains of bacterial antagonists. J Food Protect 72:85–92Google Scholar
- Liu X, Fang W, Liu L, Yu T, Lou B, Zheng X (2010) Biological control of postharvest sour rot of citrus by two antagonistic yeasts. Lett Appl Microbiol 51:30–35Google Scholar
- Nally MC, Pesce VM, Maturano YP, Muñoz CJ, Combina M, Toro ME, Castellanos de Figureoa LI, Vazquez F (2012) Biocontrol of Botrytis cinerea in table grapes by non-pathogenic indigenous Saccharomyces cerevisiae yeasts isolated from viticultural environments in Argentina. Postharvest Biol Tec 64:40–48CrossRefGoogle Scholar
- Romero D, de Vicente A, Rakotoaly RH, Dufour SE, Veening JW, Arrebola E, Cazorla FM, Kuipers OP, Paquot M, Pérez-García A (2007) The iturin and fengycin families of lipopeptides are key factors in antagonism of Bacillus subtilis toward Podosphaera fusca. Mol Plant Microbe In 20:430–440CrossRefGoogle Scholar
- Shu-Bin L, Mao F, Ren-Chao Z, Juan H, Xiao L (2012) Characterization and evaluation of the endophyte Bacillus B014 as a potential biocontrol agent for the control of Xanthomonas axonopodis pv. dieffenbachiae - induced blight of Anthurium. Biol Control. doi:http://dx.doi.org/10.1016/j.biocontrol.2012.06.002
- Weisburg WG, Barns SM, Pelletier DA, Lane DJ (1991) 16S ribosomal DNA amplification for phylogenetic study. J Bacteriol 173:697–703Google Scholar
- Yamamoto S, Harayama S (1995) PCR amplification and direct sequencing of gyrB genes with universal primers and their application to the detection and taxonomic analysis of Pseudomonas putida strains. Appl Environ Microb 61:1104–1109Google Scholar
- Zhao B, He SJ (2002) Microbiology experiment. Science Press, Beijing. (In Chinese)Google Scholar