Screening of quorum quenching activity of the bacteria isolated from dairy industry waste activated sludge
Intercellular bacterial communication process via exchange of signalling molecules acyl homoserine lactone results in various group activities like bioluminescence, antibiotic production, biofilm formation, sporulation, and virulence. The signalling molecules are targeted, and the communication is interrupted by a group of bacteria termed quorum quenching bacteria. The present study aims to isolate the quorum quenching bacteria from the waste activated sludge collected from the dairy industry effluent treatment plant and explore for its quorum quenching potential. The bacteria were cultured in the KG medium containing n-hexanoyl homoserine lactone as a sole source of carbon and nitrogen. The isolates were identified by the 16S ribosomal deoxyribonucleic acid analysis and subsequently were evaluated for its quorum quenching activity through Chromobacterium violaceum CV026 biosensor assay. The n-hexanoyl homoserine lactone degradation was quantified by GC–MS analysis. The 16S ribosomal deoxyribonucleic acid analysis revealed the isolated bacteria as Klebsiella pneumoniae (JYQ1 and JYQ5), Acinetobacter baumannii JYQ2, Pseudomonas nitroreducens JYQ3, and Pseudomonas JYQ4. The biosensor strain assay and GC–MS analysis indicated that all the isolates possessed an inherent ability to degrade N-hexanoyl homoserine lactone. The strain Pseudomonas JYQ4 exhibited the highest quorum quenching activity of 84 ± 3.3% within 6 h of incubation. The strain A. baumannii JYQ2 acted both as quorum sensing and as quorum quenching bacteria as evidenced by the decrease in quorum quenching from 79 ± 3.1 to 76.8 ± 2.5%.
KeywordsAcinetobacter baumannii Intercellular communication Klebsiella pneumoniae N-hexanoyl homoserine lactone Pseudomonas nitroreducens Quorum quenching
The authors gratefully acknowledge University Grant Commission, India, for providing Maulana Azad Senior Research Fellowship (F1-17.1/2010/MANF-SIK-PUN-5668) under the scheme of Maulana Azad National Fellowship for Minority Students. We also thank Verka Milk Plant, Bathinda, Punjab, for the waste activated sludge sample.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest.
This article does not contain any studies with human participants or animals performed by any of the authors.
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