Identification of Potential Antitubulin Agents with Anticancer Assets from a Series of Imidazo[1,2-a]quinoxaline Derivatives: In Silico and In Vitro Approaches.

Computer-aided drug design is a powerful and promising tool for drug design and development, with a reduced cost and time. In the current study, we rationally selected a library of 34 fused imidazo[1,2-a]quinoxaline derivatives and performed virtual screening, molecular docking, and molecular mechanics for a lead identification against tubulin as an anticancer molecule. The computational analysis and pharmacophoric features were represented as 1A2; this was a potential lead against tubulin, with a maximized affinity and binding score at the colchicine-binding site of tubulin. The efficiency of this lead molecule was further identified using an in vitro assay on a tubulin enzyme and the anticancer potential was established using an MTT assay. Compound 1A2 (IC50 = 4.33-6.11 µM against MCF-7, MDA-MB-231, HCT-116, and A549 cell lines) displayed encouraging results similar to the standard drug colchicine in these in vitro studies, which further confirmed the effectiveness of CADD in new drug developments. Thus, we successfully applied the utility of in silico techniques to identify the best plausible leads from the fused azaheterocycles.

Structural insight into substrate binding of Acinetobacter baumannii polyphosphate-AMP phosphotransferase (PPK2), a novel drug target.

Acinetobacter baumannii is an opportunistic pathogen known for high morbidity and mortality. It causes life-threatening infections, such as ventilator-associated pneumonia (VAP), bacteremia, meningitis, wound and urinary tract infections (UTI). Increase in carbapenem resistance exhibited by A. baumannii has accentuated the need for novel targets for effective treatment. Despite the pronounced relevance of PPK2 as a pathogenicity determinant in several pathogens, it has not been explored as a drug target in A. baumannii. The present study was piloted to investigate the substrate binding by A. baumannii PPK2 (AbPPK2), a two-domain Class II polyphosphate kinase 2. A homology model of AbPPK2 was developed and validated for molecular docking of ATP and ADP in the predicted binding pocket. Further analysis of AbPPK2 revealed a set of common residues in the catalytic cleft interacting with ATP and ADP which would be useful for the screening of inhibitors against A. baumannii.

Microaerobic conditions enhance laccase production from Rheinheimera sp. in an economical medium.

Statistical optimization of aeration conditions viz. aerobic, microaerobic and anaerobic, was performed using response surface methodology (RSM) utilizing soybean meal as medium to enhance the production of laccase from Rheinheimera sp. Maximum laccase yield (18.48 × 105 U/L) was obtained under microaerobic (static) conditions sustained for 12 h in tandem with 26 h aerobically (150 rpm) grown culture, which was 17.03-fold higher than laccase production in the starting M162 medium under aerobic conditions (150 rpm). The reduction in incubation time from 72 to 38 h and utilization of cost-effective soybean meal as medium, which is easily available from local market, have provided a promising, eco-friendly method of laccase enzyme production. Enhanced expression of laccase gene under microaerobic conditions corresponded to the increased expression of fnr (fumarate nitrate reductase) gene, the oxygen sensing global regulator. The putative FNR-binding site upstream of laccase transcription initiation site was predicted to play an imperative role in Rheinheimera sp. adaptation from aerobic to microaerobic conditions and for enhanced laccase production.

Tobramycin Stress Induced Differential Gene Expression in Acinetobacter baumannii.

Acinetobacter baumannii is a multidrug-resistant bacteria responsible for nosocomial infections with significant fatality rates globally. Therapeutic failure and relapse of infection has been associated with persister cells formation which can also lead to resistance in A. baumannii. In the present study, we observed that A. baumannii ATCC 17978 in exponential phase survived lethal concentrations of amikacin, rifampicin and ciprofloxacin by generating persister cells but was unable to survive tobramycin treatment. The transcriptome of A. baumannii ATCC 17978 was analyzed following exposure to a high concentration of tobramycin (10 × MIC) for a short period of time to study the possible mechanisms responsible for lethality. Tobramycin reduced the expression of genes involved in energy production (nuoH, nuoN, nuoM, cydA, sucC), oxidative stress protection (tauD, cysD), and nutrition uptake (ompW) significantly. In addition, hemerythrin (non-heme di-iron oxygen-binding protein) was found to be the most downregulated gene in response to tobramycin which needs to be further studied for its role in susceptibility to antibiotics. Tobramycin upregulated the expression of genes that are mainly involved in stress response (leucine catabolism, DNA repair and HicAB toxin-antitoxin system). The differentially expressed genes highlighted in the study provided insight into the probable molecular mechanism of tobramycin-induced cell death and revealed some novel targets that can be explored further for their potential to control A. baumannii.

Multicopper oxidase of Acinetobacter baumannii: Assessing its role in metal homeostasis, stress management and virulence.

A putative multicopper oxidase, encoded as CopA in the proteome of Acinetobacter baumannii 19606, and designated as AbMCO, was expressed heterologously in E. coli (pET-28a) and purified by Ni-NTA affinity chromatography. The purified AbMCO exhibited in vitro oxidase activities upon exogenous addition of ≥1 µM copper ions. Kinetic studies revealed its phenol oxidase activity as it could catalyze the oxidation of substrates viz. 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), guaiacol, pyrogallol and catechol. Additionally, AbMCO displayed siderophore oxidase activity which depicted its role in metal homeostasis and protection from the toxic redox states of copper and iron. Importantly, expression of abMCO increased manifold upon challenge with high concentrations of copper sulphate (CuSO4, 1.5 mM) and sodium chloride (NaCl, 700 mM) which suggested its protective role in stress adaptation and management. Intra-macrophage assay of abMCO-expressing and abMCO-non expressing cells depicted no significant change in the survival rate of A. baumannii inside the macrophages. These findings indicate that A. baumannii encodes a multicopper oxidase, conferring copper tolerance and survival under stress conditions but had no role in virulence of this pathogen.

Expression of Meiothermus ruber luxS in E. coli alters the antibiotic susceptibility and biofilm formation.

Quorum sensing (QS) and signal molecules used for interspecies communication are well defined in mesophiles, but there is still a plethora of microorganisms in which existence and mechanisms of QS need to be explored, thermophiles being among them. In silico analysis has revealed the presence of autoinducer-2 (AI-2) class of QS signaling molecules in thermophiles, synthesized by LuxS (AI-2 synthase), though the functions of this system are not known. In this study, LuxS of Meiothermus ruber was used for understanding the mechanism and functions of AI-2 based QS among thermophilic bacteria. The luxS gene of M. ruber was expressed in luxS- deletion mutant of Escherichia coli. Complementation of luxS resulted in significant AI-2 activity, enhanced biofilm formation, and antibiotic susceptibility. Transcriptome analysis showed significant differential expression of 204 genes between the luxS-complemented and luxS- deletion mutant of E. coli. Majority of the genes regulated by luxS belonged to efflux pumps. This elucidation may contribute towards finding novel alternatives against incessant antibiotic resistance in bacteria.Key Points• Expression of luxS in luxS-E. coli resulted in increase in biofilm index. • Reduction in the MIC of antibiotics was observed after complementation of luxS. • Downregulation of efflux pump genes was observed after complementation of luxS. • Transcriptome analysis showed that 204 genes were differentially regulated significantly.

Nucleases of bacterial pathogens as virulence factors, therapeutic targets and diagnostic markers.

New frontiers of therapy are being explored against the upcoming bacterial diseases rendered untreatable due to multiple, extreme and pan- antibiotic resistance. Nucleases are ubiquitous in bacterial pathogens performing various functions like acquiring nucleotide nutrients, allowing or preventing uptake of foreign DNA, controlling biofilm formation/dispersal/architecture, invading host by tissue damage, evading immune defence by degrading DNA matrix of neutrophil extracellular traps (NETs) and immunomodulating the host immune response. Secretory nucleases also provide means of survival to other bacteria like iron-reducing Shewanella and such functions help them adapt and survive proficiently. Other than their pro-pathogen roles in survival, nucleases can be used directly as therapeutics. One of the powerful armours of pathogens is the formation of biofilms, thus helping them resist and persist in the harshest of environments. As eDNA forms the structural and binding component of biofilm, nucleases can be used against the adhering component, thus increasing the permeability of antimicrobial agents. Nucleases have recently become a model system of intense study for their biological functions and medical applications in diagnosis, immunoprophylaxis and therapy. Rational implications of these enzymes can impact human medicine positively in future by opening new ways for therapeutics which have otherwise reached saturation due to multi drug resistance.

Contraceptive efficacy of sperm agglutinating factor from Staphylococcus warneri, isolated from the cervix of a woman with inexplicable infertility.

BACKGROUND: Voluntary control of fertility is of paramount importance to the modern society. But since the contraceptive methods available for women have their limitations such as urinary tract infections, allergies, cervical erosion and discomfort, a desperate need exists to develop safe methods. Vaginal contraceptives may be the answer to this problem, as these are the oldest ways of fertility regulation, practiced over the centuries. With minimal systemic involvement, these are also the safest. Natural substances blocking or impairing the sperm motility offer as valuable non-cytotoxic vaginal contraceptives. Antimicrobial peptides (AMPs) isolated from plants, animals and microorganisms are known to possess sperm immobilizing and spermicidal properties. Following this, in the quest for alternative means, we have cloned, over expressed and purified the recombinant sperm agglutinating factor (SAF) from Staphylococcus warneri, isolated from the cervix of a woman with unexplained infertility. METHODS: Genomic library of Staphylococcus warneri was generated in Escherichia coli using pSMART vector and screened for sperm agglutinating factor (SAF). The insert in sperm agglutinating transformant was sequenced and was found to express ribonucleotide-diphosphate reductase-α sub unit. The ORF was sub-cloned in pET28a vector, expressed and purified. The effect of rSAF on motility, viability, morphology, Mg++-dependent ATPase activity and acrosome status of human sperms was analyzed in vitro and contraceptive efficacy was evaluated in vivo in female BALB/c mice. RESULTS: The 80 kDa rSAF showed complete sperm agglutination, inhibited its Mg2+-ATPase activity, caused premature sperm acrosomal loss in vitro and mimicked the pattern in vivo showing 100% contraception in BALB/c mice resulting in prevention of pregnancy. The FITC labeled SAF was found to bind the entire surface of spermatozoa. Vaginal application and oral administration of rSAF to mice for 14 successive days did not demonstrate any significant change in vaginal cell morphology, organ weight and tissue histology of reproductive and non-reproductive organs and had no negative impact in the dermal and penile irritation tests. CONCLUSION: The Sperm Agglutinating Factor from Staphylococcus warneri, natural microflora of human cervix, showed extensive potential to be employed as a safe vaginal contraceptive.

Tetrabromobisphenol A induced oxidative stress and genotoxicity in fish Channa punctatus.

Tetrabromobisphenol A (TBBPA) is the most widely used brominated flame retardant and its increased use in common products such as plastics, electronic equipment, etc., has raised concern about its ecotoxicity. The present study was conducted to investigate the oxidative stress and genotoxic potential of TBBPA on fresh water fish Channa punctatus by measuring malondialdehyde level and DNA damage, respectively. Fish were exposed to 5.09 mg/l (1/2 of LC50) of TBBPA along with positive (acetone) and negative controls (water) for 96 h. The blood samples were collected at 24, 48, 72 and 96 h post exposure. The results of the study showed significantly increased oxidative stress and DNA damage in the exposed groups as compared to controls. The effect of duration is also found to be significant. The findings of the study would be helpful in risk assessment of TBBPA-induced oxidative stress and genotoxicity among aquatic organisms.

Contraceptive Sperm Agglutinating Proteins Identified in Staphylococcus warneri, Natural Microflora of an Infertile Woman.

Staphylococcus warneri, isolated from the cervix of an adult female with unexplained infertility, was found to agglutinate human spermatozoa in vitro leading to their death. A genomic library of S. warneri was generated using pSMART-Escherichia coli vector-host system. Approximately 3500 transformants were screened and four showed sperm agglutinating activity. Sperm agglutinating proteins (SAPs) were partially purified from the positive transformants and were found to agglutinate sperms in vitro. Cloned ORFs in positive transformants were sequenced and ORF finder identified them as endonuclease, accessory secretory protein-Asp1, accessory secretory protein-Asp2 and signal transduction protein. Mannose was found to competitively inhibit sperm agglutination, indicating that SAPs in S. warneri bind to mannose in glycoprotein receptors on the surface of sperms for agglutination. This is the first report on identification of SAPs which may be responsible for unexplained infertility in women and may be used as contraceptive agents.

Quorum sensing in thermophiles: prevalence of autoinducer-2 system.

BACKGROUND: Quorum sensing is a mechanism of cell to cell communication that requires the production and detection of signaling molecules called autoinducers. Although mesophilic bacteria is known to utilize this for synchronization of physiological processes such as bioluminescence, virulence, biofilm formation, motility and cell competency through signaling molecules (acyl homoserine lactones, AI-1; oligopeptides, peptide based system and furanosyl borate diester, AI-2), the phenomenon of quorum sensing in thermophiles is largely unknown. RESULTS: In this study, proteomes of 106 thermophilic eubacteria and 21 thermophilic archaea have been investigated for the above three major quorum sensing systems to find the existence of quorum sensing in these thermophiles as there are evidences for the formation of biofilms in hot environments. Our investigation demonstrated that AI-1 system is absent in thermophiles. Further, complete peptide based two component systems for quorum sensing was also not found in any thermophile however the traces for the presence of response regulators for peptide based system were found in some of them. BLASTp search using LuxS (AI-2 synthase) protein sequence of Escherichia coli str. K-12 substr. MG1655 and autoinducer-2 receptors (LuxP of Vibrio harveyi, LsrB of E. coli str. K-12 substr. MG1655 and RbsB of Aggregatibacter actinomycetemcomitans) as queries revealed that 17 thermophilic bacteria from phyla Deinococcus- Thermus and Firmicutes possess complete AI-2 system (LuxS and LsrB and/or RbsB). Out of 106 thermophilic eubacteria 18 from phyla Deinococcus- Thermus, Proteobacteria and Firmicutes have only LuxS that might function as AI-2 synthesizing protein whereas, 16 are having only LsrB and/or RbsB which may function as AI-2 receptor in biofilms. CONCLUSIONS: We anticipate that thermophilic bacteria may use elements of LsrB and RbsB operon for AI-2 signal transduction and they may use quorum sensing for purposes like biofilm formation. Nevertheless, thermophiles in which no known quorum sensing system was found may use some unknown mechanisms as the mode of communication. Further information regarding quorum sensing will be explored to develop strategies to disrupt the biofilms of thermophiles.

Bio-prospecting Bacterial Diversity of Hot Springs in Northern Himalayan Region of India for Laccases.

Bacterial diversity of hot springs of northern Himalayan region of India was studied and explored for laccases, the multicopper enzymes applicable in a large number of industries due to their ability to utilize a wide range of substrates. 220 operational taxonomic units (OTUs) out of 5551 sequence reads for bacterial diversity and 3 OTUs out of 19 sequence reads for Laccase like multicopper oxidases (LMCOs) diversity were generated. Bacteroidetes (74.28%) was the most abundant phylum including genus Paludibacter (66.96%), followed by phylum Proteobacteria (24.53%) including genera Chitinilyticum (7.55%) and Cellvibrio (6.14%). In case of laccase diversity, three LMCO sequences showed affiliation with proteobacteria and one with two domain laccase from uncultivable bacteroidetes. LMCO sequences belonged to H and N families.

Bio-Prospecting Laccases in the Bacterial Diversity of Activated Sludge From Pulp and Paper Industry.

Activated sludge is an artificial ecosystem known to harbor complex microbial communities. Bacterial diversity in activated sludge from pulp and paper industry was studied to bioprospect for laccase, the multicopper oxidase applicable in a large number of industries due to its ability to utilize a wide range of substrates. Bacterial diversity using 454 pyrosequencing and laccase diversity using degenerate primers specific to conserved copper binding domain of laccase like multicopper oxidase (LMCO) genes were investigated. 1231 OTUs out of 11,425 sequence reads for bacterial diversity and 11 OTUs out of 15 reads for LMCO diversity were formed. Phylum Proteobacteria (64.95 %) with genus Thauera (13.65 %) was most abundant followed by phylum Bacteriodetes (11.46 %) that included the dominant genera Paludibacter (1.93 %) and Lacibacter (1.32 %). In case of LMCOs, 40 % sequences showed affiliation with Proteobacteria and 46.6 % with unculturable bacteria, indicating considerable novelty, and 13.3 % with Bacteroidetes. LMCOs belonged to H and J families.

Immunoprotective potential of in silico predicted Acinetobacter baumannii outer membrane nuclease, NucAb.

Acinetobacter baumannii is an emerging multi-drug resistant pathogen causing significant mortality in hospitalized ICU patients which demands developing new methods for prevention and treatment. A. baumannii 19606 proteome was analysed in silico through the online tool Vaxign for finding potential vaccine candidates. The selected nuclease (NucAb) was predicted to possess all the attributes of a promising vaccine candidate like outer membrane localization, high adhesin probability (0.53), one transmembrane helix only, non-homology to human proteins and presence of B-cell and T-cell epitopes binding with high affinity (percentile rank≤1) to HLA alleles prevalent at high frequency in North Indian populations. nucAb gene was highly prevalent (100%) among the clinical isolates (40/40) and conserved (>98%) among NCBI sequenced Acinetobacter strains. It was cloned in pET28a, purified and its immunoprotective potential was validated in murine pneumonia model. Immunization of BALB/c mice with recombinant NucAb (25µg) elicited high antibody titre (1-5×10(5)) which reduced bacterial load by 5 log cycles in lungs of mice challenged with optimized lethal dose (10(8)CFU). Lung histopathology revealed marked suppression of inflammation. Pro-inflammatory cytokines (TNF-α and IL-6) levels were reduced significantly and anti-inflammatory (IL-10) cytokine increased in lungs and serum leading to decreased severity and slow progression of disease. Though active immunization showed low survival rate (20%), passive immunization improved the survival (40%). This is the first study reporting an outer membrane nuclease as a vaccine candidate in Gram negative bacterium, A. baumannii through reverse vaccinology approach.

Critical factors affecting laccase-mediated biobleaching of pulp in paper industry.

Next to xylanases, laccases from fungi and alkali-tolerant bacteria are the most important biocatalysts that can be employed for eco-friendly biobleaching of hard and soft wood pulps in the paper industry. Laccases offer a potential alternative to conventional, environmental-polluting chlorine and chlorine-based bleaching and has no reductive effect on the final yield of pulp as compared to hemicellulases (xylanases and mannanases). In the last decade, reports on biobleaching with laccases are based on laboratory observations only. There are several critical challenges before this enzyme can be implemented for pulp bleaching at the industrial scale. This review discusses significant factors like redox potential, laccase mediator system (LMS)-synthetic or natural, pH, temperature, stability of enzyme, unwanted grafting reactions of laccase, and cost-intensive production at large scale which constitute a great hitch for the successful implementation of laccases at industrial level.

Cloning, molecular modeling, and docking analysis of alkali-thermostable ß-mannanase from Bacillus nealsonii PN-11.

An alkali-thermostable ß-mannanase gene from Bacillus nealsonii PN-11 was cloned by functional screening of E. coli cells transformed with pSMART/HaeIII genomic library. The ORF encoding mannanase consisted of 1100 bp, corresponding to protein of 369 amino acids and has a catalytic domain belonging to glycoside hydrolase family 5. Cloned mannanase was smaller in size than the native mannanase by 10 kDa. This change in molecular mass could be because of difference in the glycosylation. The tertiary structure of the ß-mannanase (MANPN11) was designed and it showed a classical (α/ß) TIM-like barrel motif. Active site of MANPN11 was represented by 8 amino acid residues viz., Glu152, Trp189, His217, Tyr219, Glu247, Trp276, Trp285, and Tyr287. Model surface charge of MANPN11 predicted that surface near active site was mostly negative, and the opposite side was positive which might be responsible for the stability of the enzymes at high pH. Stability of MANPN11 at alkaline pH was further supported by the formation of a hydrophobic pocket near active site of the enzyme. To understand the ability of MANPN11 to bind with different substrates, docking studies were performed and found that mannopentose fitted properly into active site and form stable enzyme substrate complex.

Production of thermo-alkali-stable laccase and xylanase by co-culturing of Bacillus sp. and B. halodurans for biobleaching of kraft pulp and deinking of waste paper.

To reduce pollution and cost of treatment for fresh and recycled paper, co-production of xylanase and laccase was carried out in the same production medium using two compatible species of Bacillus. These co-produced enzymes were used for deinking of old newsprint (ONP) and biobleaching of eucalyptus Kraft pulp. Solid-state co-cultivation of Bacillus sp. and B. halodurans FNP135 was optimized statistically by response surface methodology for the co-production of xylanase (X) and laccase (L). A significant increase in production of xylanase (2.1-fold, 1,685 IU/g) and laccase (2.04-fold, 2,270 nkat/g) was observed under optimized conditions viz. pH (10.5), inoculum size (10 + 10 %) and moisture:substrate ratio (0.8:1). Both the enzymes showed identical temperature and pH optima of 70 °C and 9, respectively, and were used for deinking of ONP pulp and biobleaching of kraft pulp. In case of ONP pulp deinking, the XL treatment increased brightness (11.8 %), freeness (17.8 %), breaking length (34.8 %), burst factor (2.77 %) and tear factor (2.4 %). In case of kraft pulp biobleaching, XL treatment showed a significant increase in brightness (13 %), whiteness (106.15 %) breaking length (49 %), burst factor (6.9 %), tear factor (23 %), and viscosity (11.68 %) and reduction in kappa number (15 %) after alkali extraction and peroxide stage. This enhancement of pulp properties revealed a synergistic effect of xylanase and laccase produced in one setup.

Pyocyanin stimulates quorum sensing-mediated tolerance to oxidative stress and increases persister cell populations in Acinetobacter baumannii.

Acinetobacter baumannii and Pseudomonas aeruginosa are nosocomial pathogens with overlapping sites of infection. This work reports that the two can coexist stably in mixed-culture biofilms. In a study intended to improve our understanding of the mechanism of their coexistence, it was found that pyocyanin, produced by P. aeruginosa that generally eliminates competition from other pathogens, led to the generation of reactive oxygen species (ROS) in A. baumannii cells, which in response showed a significant (P ≤ 0.05) increase in production of enzymes, specifically, catalase and superoxide dismutase (SOD). This work shows for the first time that the expression of catalase and SOD is under the control of a quorum-sensing system in A. baumannii. In support of this observation, a quorum-sensing mutant of A. baumannii (abaI::Km) was found to be sensitive to pyocyanin compared to its wild type and showed significantly (P ≤ 0.001) lower levels of the antioxidant enzymes, which increased on addition of 5 µM N-(3-hydroxydodecanoyl)-l-homoserine lactone. Likewise, in wild-type A. baumannii, there was a significant (P < 0.01) decrease in the level of anti-oxidant enzymes in the presence of salicylic acid, a known quencher of quorum sensing. In the presence of amikacin and carbenicillin, A. baumannii formed 0.07 and 0.02% persister cells, which increased 4- and 3-fold, respectively, in the presence of pyocyanin. These findings show that pyocyanin induces a protective mechanism in A. baumannii against oxidative stress and also increases its persistence against antibiotics which could be of clinical significance in the case of coinfections with A. baumannii and P. aeruginosa.

A process for reduction in viscosity of coffee extract by enzymatic hydrolysis of mannan.

Mannan is the main polysaccharide component of coffee extract and is responsible for its high viscosity, which in turn negatively affects the technological processing involved in making instant coffee. In our study, we isolated mannan from coffee beans and extract of commercial coffee and it was enzymatically hydrolyzed using alkali-thermostable mannanase obtained from Bacillus nealsonii PN-11. As mannan is found to be more soluble under alkaline conditions, an alkali-thermostable mannanase is well suited for its hydrolysis. The process of enzymatic hydrolysis was optimized by response surface methodology. Under the following optimized conditions viz enzyme dose of 11.50 U mannanase g(-1) coffee extract, temperature of 44.50 °C and time of 35.80 min, significant twofold decrease in viscosity (50 mPas to 26.00 ± 1.56 mPas) was achieved. The application of this process in large-scale industrial production of coffee will help in reduction of energy consumption used during freeze-drying. It will also make technological processing involved in making coffee more economical.

Lactonase-expressing Lactobacillus plantarum NC8 attenuates the virulence factors of multiple drug resistant Pseudomonas aeruginosa in co-culturing environment.

Pseudomonas aeruginosa possesses an arcade of both cell-associated and extracellular cytotoxic virulence factors which are regulated by a multi-component quorum sensing system. Many research studies report success of lactonase in combating the pathogenicity of P. aeruginosa but delivery of lactonase remains a challenge. The present study aims at developing a delivery vehicle for lactonase. Lactobacillus plantarum NC8 was used as host for aiiA (Bacillus thuringiensis 4A3 lactonase gene) using pSIP409 expression vector. pSIP409: aiiA construct was stably maintained in L. plantarum NC8. Co-culturing of multi-drug resistant (MDR) clinical isolates of P. aeruginosa and PAO1 with recombinant L. plantarum NC8 led to significant reduction (p < 0.001) in extracellular virulence factors like pyocyanin, protease, elastase and rhamnolipids in P. aeruginosa and also showed significant reduction in adhesion of P. aeruginosa strains to uroepithelial cells in vitro. This study shows the heterologous expression of AiiA lactonase in L. plantarum NC8. Co-culturing of lactonase expressing L. plantarum NC8 with MDR P. aeruginosa strains led to attenuation of their virulence significantly. These results underscore the potential application of recombinant L. plantarum NC8 with anti-quorum sensing properties to control infections caused by multidrug resistant P. aeruginosa.