ABSTRACT
Tuberculosis (TB) is a communicable disease caused by Mycobacterium tuberculosis (M. tuberculosis). WHO estimated that 10.4 million new (incident) TB cases worldwide in year 2016. The increased prevalence of drug resistant strains and side effects associated with the current anti-tubercular drugs make the treatment options more complicated. Hence, there are necessities to identify new drug candidates to fight against various sub-populations of M. tuberculosis with less or no toxicity/side effects and shorter treatment duration. Bacteriocins produced by lactic acid bacteria (LAB) attract attention of researchers because of its 'Generally recognized as safe' status. LAB and its bacteriocins possess an effective antimicrobial activity against various bacteria and fungi. Interestingly bacteriocins such as nisin and lacticin 3147 have shown antimycobacterial activity in vitro. As probiotics, LAB plays a vital role in promoting various health benefits including ability to modulate immune response against various infectious diseases. LAB and its metabolic products activate immune system and thereby limiting the M. tuberculosis pathogenesis. The protein and peptide engineering techniques paved the ways to obtain hybrid bacteriocin derivatives from the known peptide sequence of existing bacteriocin. In this review, we focus on the antimycobacterial property and immunomodulatory role of LAB and its metabolic products. Techniques for large scale synthesis of potential bacteriocin with multifunctional activity and enhanced stability are also discussed.
ABSTRACT
The present study reports the bioactive potential of actinobacteria isolated from certain under-studied regions in India. Soil and sediment samples and mangrove leaves were collected from 16 different under-studied regions in India. Actinobacteria was isolated by adopting selective isolation methods. Totally 158 actinobaterial cultures were selected from the collected terrestrial, marine and plant samples. More number of colonies was isolated from magnesite area, Kolli Hills and forest area in Himachal Pradesh. Majority of the isolates produced powdery (40%) and leathery (25%) colonies with white (38%) or Gray (37%) colour aerial mycelium. Bioactive compound from all the isolates were produced by agar surface fermentation and its activity was tested by agar plug method against S. aureus, E. coli and C. albicans. About 64 out of 158 cultures showed antibacterial activity in which 62 cultures was active against S. aureus whereas 26 were active against E. coli. Twenty three actinobacterial cultures were exhibited antifungal activity. About 11 actinobacterial cultures were active against both S. aureus and E. coli. In antifungal testing whereas fourteen actinobacterial cultures were found to be active against S. aureus, E. coli and C. albicans. Maximum of 21 antibacterial cultures and antifungal cultures were obtained from Magnesite soil followed by 12 antibacterial and 7 antifungal cultures were obtained from the soil sample collected from Himachal Pradesh. This evidenced that the under-studied ecosystems in India are the promising source for bioactive actinobacteria with broad spectrum antibacterial and antifungal activity. Further studies on the potential actinobacterial strains result in the isolation of broad spectrum antimicrobial metabolites.
ABSTRACT
Streptomyces from rare ecosystems is the promising source for secondary metabolites exhibiting diverse biological activities. The present study reports the antioxidant activity and antimicrobial activity against biofilm forming bacteria by the pigment produced from Desert soil Streptomyces sp. D25. Crude pigment from the Streptomyces sp D25 was produced by agar surface fermentation using yeast extract malt extract agar and extracted using ethyl acetate. Antioxidant activity of pigment was tested at 100-500μg/ml concentration by DPPH and nitric acid scavenging assay. Antimicrobial activity against the biofilm forming bacteria was tested by disc diffusion method. The Streptomyces pigment showed 35.63% and 96.19% free radical scavenging activity in DPPH assay and nitric oxide assay, respectively. The results of radical scavenging activity of pigment in DPPH and nitric oxide assay showed its antioxidant potential. In antimicrobial assay, the pigment showed 10-20 mm inhibition against biofilm forming bacteria at 25μg/ml. Further in vivo studies on this Streptomyces pigment pave the way for its biomedical applications.
ABSTRACT
An attempt was made for the isolation of colicinogenic E. coli from cow and sheep dung samples. Total of 112 E. coli isolates were collected from sheep and cow dung samples in which 63 isolates are from cow dung and 49 isolates are from sheep dung samples. In the screening for colicin production, two E. coli isolates C22 and C51 from cow dung sample and one isolate S39 from sheep dung sample showed activity against the pathogenic strain E. coli O157:H7. Colicin production by all the three E. coli isolates was found to be enhanced by 0.25mg/l of mitomycin-c and three hours of incubation at 370C. Plasmid DNA was isolated from colicinogenic E. coli strains by alkali lysis method and their molecular weight was found to be 6.5 kb. The transformation experiment carried out with the standard strain E. coli DH5 confirmed that the plasmids were col-plasmids. The three colicinogenic E. coli strains isolated in this study will be a candidate to develop as probiotic for veterinary applications.