Diversity and Polymorphism in AHL-Lactonase Gene (aiiA) of Bacillus

Abstract

To explore bacterial diversity for elucidating genetic variability in acylhomoserine lactone (AHL) lactonase structure, we screened 800 bacterial strains. It revealed the presence of a quorum quenching (QQ) AHL-lactonase gene (aiiA) in 42 strains. These 42 strains were identified using rrs (16S rDNA) sequencing as Bacillus strains, predominantly B. cereus. An in silico restriction endonuclease (RE) digestion of 22 AHL lactonase gene (aiiA) sequences (from NCBI database) belonging to 9 different genera, along with 42 aiiA gene sequences from different Bacillus spp. (isolated here) with 14 type II REs, revealed distinct patterns of fragments (nucleotide length and order) with four REs; AluI, DpnII, RsaI, and Tru9I. Our study reflects on the biodiversity of aiiA among Bacillus species. Bacillus sp. strain MBG11 with polymorphism (115Alanine > Valine) may confer increased stability to AHL lactonase, and can be a potential candidate for heterologous expression and mass production. Microbes with ability to produce AHL-lactonases degrade quorum sensing signals such as AHL by opening of the lactone ring. The naturally occurring diversity of QQ molecules provides opportunities to use them for preventing bacterial infections, spoilage of food, and bioremediation.

Microbes, Antimicrobials and Resistance: The Battle Goes On

“…QSIs have been primarily targeting biosynthesis and degradation of signal molecules and their receptors. QSI from prokaryotes, animal and plant origin, have been widely reported [2][3][4][5][6]. Synthetic QSIs have more variety, efficacy and efficiency in comparison to naturally occurring ones [3].…”

Detection of Quorum Sensing Signal Molecules in Edwardsiella ictaluri Ei-151

“…3) AHL-based QS in some pathogenic species are well studied and have been shown to relate to their virulence [6]. It has been reported that some prokaryotes and a few eukaryotic organisms, especially Bacillus spp., can produce AHL-degrading enzymes such as AHL-lactonases and AHL-acylases to degrade these signals, which is called quorum quenching (QQ) [23,24]. QQ can be exploited as potentially novel antibiotic-free therapeutics to protect from bacterial infections [25].…”

Cross-Species Induction and Enhancement of Antimicrobial Properties in Response to Gamma Irradiation in Exiguobacterium sp. HKG 126

“…There are several reports which have shown the production of such type of communication molecules from bacterial organisms such as Edwardsiella ictaluri [17]. Besides to these QS molecules, production of some other molecules which can degrades these QS signals by inhibiting the production of QS signal molecules or degradation of the AHLs, also has been reported from bacterial organisms, called quorum quenching (QQ) [18][19][20][21]. Natural genetic transformation is also believed to be the essential mechanism for exploiting innate microbial capacity in bacterial populations, during mixed culture fermentation via horizontal gene transfer.…”