Fohad Mabood Husain1,2*, Iqbal Ahmad2, Nasser Abdulatif Al-Shabib1, Riyazuddin1, Mohd Shahnawaz Khan3, Yahya Ahmed Mohammed4 and Abdullah Althubiani5

1 Department of Food Science and Nutrition, College of Food and Agricultural Sciences, King Saud University, Riyadh-11541, Kingdom of Saudi Arabia.
2 Department of Agricultural Microbiology, Aligarh Muslim University, Aligarh – 202 002, India.
3 Department of Biochemistry, College of Science, King Saud University, Riyadh-11541, Kingdom of Saudi Arabia.
4 College of Engineering, King Saud University, Riyadh-11541, Kingdom of Saudi Arabia. 5Faculty of Applied Science, Umm Al-Qura University, Makkah-21955, Kingdom of Saudi Arabia.

Received on 13 January 2016 and accepted on 19 April 2016

 

ABSTRACT

Indiscriminate use of antibiotics as led to development of drug resistance among infection causing bacteria rendering the current antibiotic therapy ineffective. This has compelled the scientific community across the globe to look for new drug targets. Since quorum sensing plays a key in the expression of virulence genes and biofilm formation it can be a potential target for curing infections caused by pathogens. Therefore, keeping in mind the ubiquitous an diverse nature of quorum quenching bacteria, date palm rhizospheric soil of Saudi Arabia was selected to screen for quorum quenching bacteria. In ther present study, SBF1 strain demonstrated promising inhibition of violacein Chromobacterium violaceum 12472 biosensor strain and was selected for anti-virulence assay. Using 16S rDNA analysis the strain SBF1 was identified as Bacillus amyloliquefaciens (GenBank Accession Number: KC494392). Culture extract of SBF1 demonstrated dose-dependent (0.75–6 mg/ml) reduction against the QS regulated violacein production in C. violaceum (45–79%) and LasB elastase (4.9-63.8%), total protease (34.3–84.4%) and pyocyanin (32.7-63.7%) in PAO1. The extract also decreased the swarming migration of CV12472 and PAO1 significantly. Biofilm forming ability of PAO1 was also significantly impaired after treatment with SBF1 extract. Ring opening assay suggests that the anti-QS activity is due the production of lactonase enzyme. Findings of the present study demonstrate the anti-QS and antibiofilm potential of SBF 1 extract. Quorum quenching ability of SBF1 can be exploited to treat bacterial infections, to prevent food spoilage and in bioremediation.

Keywords

Bacillus amyloliquefaciens, biofilm, date palm, lactonase, quorum sensing, virulence.