In-vitro antimicrobial susceptibility pattern of lipopeptide against drug resistant Vibrio species

BACKGROUND

The unrestricted application of antibiotics increased antimicrobial resistance in bacteria through horizontal gene transfer of resistant genes from the pathogenic sources and the evolution of multi-drug resistance organisms. The application of antibiotics caused severe risk to human health because animals may transmit diseases to humans. Hence, the search of novel antimicrobial agents from microbial sources is an urgent need.

METHODS

A lipopeptide producing stain SU05 was isolated from the pond water by serial dilution method. The lipopeptide yield was improved after optimization method and the yield was analyzed using High Performance Liquid chromatography. The influence of wheat bran (0.5%-2.5%) and rice bran (0.5%-2.5%), pH (5.5-8.5), temperature (25-40 °C) were screened to improve the production of lipopeptides by stain SU05 in submerged fermentation. Antibacterial activity of crude lipopeptide was tested against Vibrio anguillarum, Vibrio harveyi, Vibrio vulnificus, Vibrio salmonicida, Vibrio septicus, Vibrio fischeri, and Vibrio splendidus. The influence of lipopeptide on enzymes and antimicrobial property was analyzed.

RESULTS

Lipopeptide production was improved after nutrient supplements and optimization of physical factors. Lipopeptide showed potent activity against multi-drug resistant bacterial strains such as, V. anguillarum, V. harveyi, V. vulnificus, V. salmonicida, V. septicus, V. fischeri, and V. splendidus. Lipopeptide shows stability on various enzymes and this clearly revealed that the purified lipopeptide was highly stable in the presence of proteolytic enzymes. The findings suggest that lipopeptide SU05 characterized from the bacteria can survive at acidic environment in the intestine, and could be used to formulate fish feed.

CONCLUSIONS

The finding showed that the characterized lipopepties synthesized by B. amyloliquefaciens SU05 had a broad spectrum antibiotic potential against multidrug resistant Vibriosis causing bacterial pathogens. They were highly stable at broad temperature and pH ranges. These results demonstrated stability of lipopeptide at extreme conditions. The stability and activity of lipopeptide at extreme climatic condition is also useful for the application in pharmaceutical and food processing industries.

Impact and fungitoxic spectrum of Trachyspermum ammi against Candida albicans, an opportunistic pathogenic fungus commonly found in human gut that causes Candidiasis infection

BACKGROUND

Trachyspermum ammi (commonly known as Ajwain), a medicinal plant of the Apiaceae family is scientifically acknowledged to harbor potential bioactive compounds for the treatment of gastrointestinal issues, loss of appetite, bronchial difficulties, cough, inflammation, diarrhoea, headache, hypertension, stomach discomfort, bronchitis and influenza. Candida albicans is generally a commensal fungus found in the gastrointestinal and genitourinary systems.

OBJECTIVE

This study was focused on secondary metabolites of T. ammi and its effects towards candidiasis infection as caused by C. albicans.

METHODS

Phytochemical components of T. ammi as a crude extract were extracted through maceration method using three polar (ethanol, methanol and water) and two non-polar (chloroform and diethyl ether) solvents and subjected to 14 phytochemical tests. Further, the crude extract of T. ammi was analyzed over gas chromatography-mass spectroscopy (GC-MS) and Fourier transform infrared spectroscopy (FTIR). Evaluation of antimicrobial property of the extract was carried out by minimum fungal concentration (MFC) and minimal inhibitory concentration (MIC). In addition, cell reduction assay was performed using flowcytometry to confirm the antifungal effect of Ajwain crude extract.

RESULTS

The aqueous extract showed high presence of phytochemicals including alkaloids, carbohydrates, flavonoids, resins, steroids, tannins, inorganic acids, organic acids, phenolic compounds, amino acids, protein and coumarins. GCMS analysis revealed seven bioactive compounds, in which thymol was detected in significant amount in the chromatogram. FTIR performance showed the presence of various stretching vibration including OH, CH, CC, CO, CN and COC. However, the MFC and MIC of Ajwain extracts using different solvent showed that the methanolic extract possesses maximum antifungal efficacy at 250 μg/ml and 15.6 μg/ml, respectively. In addition, cell reduction assay exhibited significant cell reduction in Ajwain methanolic extract compared to the other crude extracts used in the study.

CONCLUSION

Overall, the findings revealed that Ajwain methanolic crude extract has antifungal activity against C. albicans; however, that further needs to be established at molecular level.