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Microb Pathog. 2017 Oct;111:519-526. doi: 10.1016/j.micpath.2017.08.020. Epub 2017 Aug 25.

Isolated Pseudomonas aeruginosa strain VIH2 and antagonistic properties against Ralstonia solanacearum.

Ge X1, Wei W1, Li G1, Sun M1, Li H1, Wu J2, Hu F3.

Author information

1
Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China.
2
Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China. Electronic address: wujun2013@njau.edu.cn.
3
Soil Ecology Lab, College of Resources and Environmental Sciences, Nanjing Agricultural University, No. 6 TongWei Road, Nanjing 210095, Jiangsu Province, People's Republic of China. Electronic address: fenghu@njau.edu.cn.

Abstract

The aim of this study was to isolates with antagonist activity against R. solanacearum. Thirty-two bacterial isolates were obtained from samples, and they were screened for potential antagonistic activity against R. Solanacearum. Using the agar spot method, ten out of the 21 tested bacteria showed antilisterial activity. VIH2 had the highest inhibitory effect on the growth of R. Solanacearum. Based on 16S rDNA and Biolog test analysis, the strain VIH2 was identified as Pseudomonas aeruginosa. Single-factor and Response Surface Methodology experiments were used to optimize the culture medium and conditions. This study was to explore whether the hemolysin-co-regulated protein secretion island I (HSI-I)-encoded type VI secretion system (T6SS) in Pseudomonas can be used as a biological control approach against Ralstonia solanacearum under field conditions. Bacterial competition assay showed that the HSI-I type T6SS of strain VIH2 exhibited dramatic antibacterial killing activity against R. solanacearum. The HSI-I T6SS of P. aeruginosa was regulated by the ppKA gene. We disrupted the gene ppKA in VIH2 by a single crossover to yield the VIH2 (ΔppKA) mutant. The antagonism of VIH2 was significantly decreased by ppKA gene disruption. In conclusion, our data supported the idea that HSI-I T6SS plays a crucial role in the antagonistic action of strain VIH2 against R. solanacearum. This alternative approach for antagonism against R. solanacearum might help develop attenuated strains of engineered bacteria for biological control.

KEYWORDS:

Antagonist activity; Pseudomonas aeruginosa; Ralstonia solanacearum; ppKA

PMID:
28847494
DOI:
10.1016/j.micpath.2017.08.020
[Indexed for MEDLINE]

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