Potential of a Quorum Quenching Bacteria Isolate Ochrobactrum intermedium D-2 Against Soft Rot Pathogen Pectobacterium carotovorum subsp. carotovorum

Abstract

Quorum quenching (QQ) is a promising strategy for preventing and controlling quorum sensing (QS)-mediated bacterial infections. It interferes with QS by the inhibition of signal synthesis, the detection of enzyme-catalyzed degradation, and the modification of signals. N-Acyl homoserine lactones (AHLs) represent a family of widely conserved QS signals involved in the regulation of virulence factor production in many Gram-negative bacterial pathogens. In this study, AHL-degrading bacterial strains were isolated, and the most efficient one was evaluated for its potential against QS-mediated pathogens. Results showed that an AHL-degrading bacteria Ochrobactrum intermedium D-2 effectively attenuated maceration produced by the pathogen Pectobacterium carotovorum subsp. carotovorum (Pcc) on radish and potato slices. Strain D-2 exhibited a superior AHL degradation activity and efficiently degraded various AHLs, including N-hexanoyl-L-homoserine lactone (C6HSL), N-(3-oxohexanoyl)-L-homoserine lactone (3OC6HSL), N-(3-oxooctanoyl)-L-homoserine lactone (3OC8HSL), and N-(3-oxododecanoyl)-L-homoserine lactone (3OC12HSL). Analysis of the degradation products of AHL by gas chromatography-mass spectrometry led to the identification of N-cyclohexyl-propanamide and propanamide as the main intermediate products, suggesting that AHL was degraded by hydrolysis. Annotation and analysis of the whole genome sequence of strain D-2 revealed the presence of an AHL-lactonase, termed AidF. Moreover, the application of strain D-2 was able to substantially reduce the disease severity caused by Pcc on host plants. These results reveal the biochemical basis of a highly efficient AHL-degrading bacterial isolate and present the potential to attenuate Pcc virulence through QQ.

Characterization of a Novel Quorum-Quenching Bacterial Strain, Burkholderia anthina HN-8, and Its Biocontrol Potential against Black Rot Disease Caused by Xanthomonas campestris pv. campestris

“…The prevention and control of black rot disease have become important concerns, due to the hugely destructive impacts of block rot disease on the productivity and quality of cruciferous plants [ 11 ]. In recent years, QQ has been increasingly interested in the development of a biocontrol method based on QS of microorganisms as an alternative and effective way to control plant diseases [ 16 , 17 , 47 , 48 ]. Among all of the methods of QQ, biocontrol bacteria with degrading signal molecule activity have appeared as efficient tools in plant disease management [ 49 ].…”

“…Each treatment was repeated three times. The treated plants were observed daily, and disease incidence and disease severity were recorded from the inoculation [ 16 ]. The details of the tests was described as follows.…”

“…QS plays an important role in bacterial adaptation in harsh environments. In addition, QS can also regulate functions related to pathogenicity [ 16 , 17 ]. Through the QS system, microorganisms evaluate their cell density, above a threshold level, and trigger collective developmental changes through synthesis, detection, and response to chemical signals known as autoinducers (AIs) [ 18 , 19 ].…”

Improving the production of AHL lactonase AiiO-AIO6 from Ochrobactrum sp. M231 in intracellular protease-deficient Bacillus subtilis

“…The HPLC method is an e cient method for quantifying AHLs, but QQ enzymes show low sensitivity to most metal ions and chemicals, and AHLs are sensitive to pH and temperature (Yates et al 2002). Most enzymes such as AiiA (Yates et al 2002), AiiK (Dong et al 2018), AidF (Fan et al 2020) and AiiO-AIO6 can be inhibited by sodium dodecyl sulfate (SDS) (Zhang et al 2011), so SDS is usually used as an inhibitor to stop the enzyme reaction (Wang et al 2004). The strongly acidic group of SDS can bind to the reversed-phase column where it will serve as an ion exchanger and can interfere with RPLC separation (Kawasaki and Suzuki 1990), which seriously affects the HPLC detection.…”

Improving the production of AHL lactonase AiiO-AIO6 from Ochrobactrum sp. M231 in intracellular protease-deficientBacillus subtilis

“…The HPLC method is an e cient method for quantifying AHLs, but QQ enzymes show low sensitivity to most metal ions and chemicals, and AHLs are sensitive to pH and temperature (Yates et al 2002). Most enzymes such as AiiA (Yates et al 2002), AiiK (Dong et al 2018), AidF (Fan et al 2020) and AiiO-AIO6 can be inhibited by sodium dodecyl sulfate (SDS)(Zhang et al 2011), so SDS is usually used as an inhibitor to stop the enzyme reaction (Wang et al 2004). The strongly acidic group of SDS can bind to the reversed-phase column where it will serve as an ion exchanger and can interfere with RPLC separation (Kawasaki and Suzuki 1990), which seriously affects the HPLC detection.…”