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R. Ilayaraja ¹, Radhamadhavan ²

Affiliations
1 Department of Microbiology, S.R.M. Medical College Hospital and Research Centre, S.R.M. University, Kattankulathur (T.N.), IN
2 Department of Microbiology, SRM Medical College Hospital and Research Centre, SRM University, Kattankulathur (T.N.), IN

Abstract

Breast milk is the primary food for an infant. Chief ingredients of breast milk include lactobacillus strains. Lactobacillus strains isolated from breast milk were investigated for their antimicrobial activity against pathogenic microorganisms. The antibacterial activity is attributed to bacteriocin secreted by Lactobacillus. Bacteriocin present in cell free supernatants of Lactobacillus reuteri exhibited inhibitory activity against microorganisms such as Escherichia coli, Shigella dysentriae, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Proteus spp. and Vibrio cholera by agar well diffusion method. Optimization of bacteriocin production and characterization of extra cellular bacteriocin were studied. The bacteriocin produced by Lactobacillus reuteri was stable at 600C for 10 minutes, but inactivated by heating at 80°C for 10 minutes. It was stable at pH 4.0 to 7.0 but sensitive to pH 9.0. 1% and 2% sodium chloride enhanced the production of bacteriocin from 25% to 75% in MRS broth. Molecular weight of bacteriocin purified by ammonium sulphate precipitation method was 2.5 kDa. Thus, bacteriocin of Lactobacillus reuteri strains isolated from human milk exhibited antibacterial activity against common clinical pathogens. It also exhibited properties of a good probiotic.

Keywords

Bacteriocin, Antimicrobial Activity, Lactobacillus reuteri, Human Health.

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T. Murugan ¹, Radhamadhavan ²

Affiliations
1 SRM Medical College Hospital and Research Institute, SRM University, Kattankulathur (T.N.), IN
2 Department of Microbiology, SRM Medical College Hospital and Research Institute, SRM University, Kattankulathur (T.N.), IN

Abstract

The cyanobacterium Spirulina platensis, a photoautotroph, is a good food supplement because of its high protein content. It is also an excellent source of pigments like phycocyanin, vitamins and lipids. The present study was carried out to obtain enhanced yield of Spirulina biomass and the pigment C-phycocyanin. Modified Zarrouk's medium was used as the basal medium (it also served as control), in which four different supplements(Multivitamin tablets, Tender coconut water, Cow dung extract and Cow urine) at 4 different concentration i.e., 250mg, 500mg, 750mg and 1000mg/l for multivitamin tablets and 1ml, 10ml, 50ml and 100ml for tender coconut water, cow dung extract and cow urine were added. The cultivation was carried out in a 1000ml Erlenmeyer flask's for a period of 20 days at room temperature with artificial aeration and lighting. The growth was monitored by direct microscopic count (DMC), optical density (OD) and dry biomass on daily basis till 20^th day. It was observed that, the first two concentrations of all the four media promoted the growth whereas the last two did not favour the growth. Multivitamin at 250mg/l was found to be very good enhancer for biomass (2.84g/l) whereas, the cow urine at the concentration 10ml/l was the least enhancer (1.40g/l) when compared to control (2.46g/l). In terms of C-phycocyanin yield, the multivitamin at the concentration of 500mg/l showed the highest concentration (0.524mg/g (5.24%) of biomass mass).

Keywords

Spirulina platensis, Zarrouk’s Medium, C-Phycocyanin, DMC, OD, Biomass.

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R. Ilayaraja ¹, Radhamadhavan ¹

Affiliations
1 Department of Microbiology, S.R.M. Medical College Hospital and Research Centre, SRM University, Kattankulathur, Kancheepuram (T.N.), IN

Abstract

The present study was conducted to determine the probiotic properties of Lactobacillus fermentum and Lactobacillus reuteri isolated from human breast milk. The samples were inoculated with MRS medium and incubated for 48 hrs at 37°C under anaerobic incubation. The identification of the culture was based on characteristic of Lactobacilli as presented in the Bersey’s Mannual of Determinative Bacteriology, carrying out morphology, gram stain, catalase, oxidase and other biochemical tests, growth at 150, 37°C and 45°C and fermentation of different carbon sources. Selection of the strain included various criteria such as agreement with biosafety aspects, antibiotic susceptibility test, tolerance to low pH, bile and NaCl concentration, temperature, Hemolytic activity and antimicrobial activity. This result suggests that these two strains are favorable for use as probiotics. It should be suitable strains for probiotic use of human being and animals. L. fermentum had high probiotic activity when compared to L.reuteri.

Keywords

MRS Medium, Probiotic, Antimicrobial Therapy, Lactobacillus.

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T. Murugan ¹, Radhamadhavan ¹

Affiliations
1 Department of Microbiology, S.R.M. Medical College Hospital and Research Institute, S.R.M. University, Kattankulathur, Kancheepuram (T.N.), IN

Abstract

C-phycocyanin was extracted from laboratory grown Spirulina platensis, and the identity was confirmed using standard Cphycocyanin, by HPTLC and SDS-PAGE. It was then partially purified and screened for antibacterial activity. The results were compared with standard C-phycocyanin (Sigma-Aldrich) and standard antibiotics. There were 6 bacterial isolates (Clinical isolates) assayed for antimicrobial activity. The study proved that the C-phycocyanin possessed antibacterial activity which was more potent than standard C-phycocyanin.

Keywords

C-Phycocyanin, Antimicrobial Activity, Partial Purification, Screening, Minimum Inhibitory Concentrations.

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