Enhancement of Growth and Bioactivities of Probiotic Bacterium Streptococcus thermophilus as Influenced by Lactalbumin Hydrolysate and Inulin Supplementation in Skimmed Milk Medium
A. R. Shyam Sundar
Department of Biomedical Sciences, Sri Ramachandra University, Chennai, India
Lalitha Vaidyanathan *
Department of Biomedical Sciences, Sri Ramachandra University, Chennai, India
*Author to whom correspondence should be addressed.
Abstract
Aims: To determine the probiotic potential of Streptococcus thermophilus and effects of lactalbumin hydrolysate (whey protein) and inulin (prebiotics) supplementation in the production medium on the growth and bioactivity profile of S. thermophilus under different pH and temperature conditions.
Place and Duration of Study: The research work was carried out in Microbiology laboratory, Department of Biomedical Sciences, Sri Ramachandra University, India between May 2015 and August 2015.
Methodology: S. thermophilus NCDC 74 was initially screened for better growth in three production media. The parameters examined in the study were specific growth rate and yield coefficient, anti-oxidant, anti-adhesive and anti-pathogenic activities, antibiotic and drug resistance and acidic pH tolerance. The collected data were analysed with IBM.SPSS statistics software 23.0 Version.
Results: The skimmed milk medium showed maximum growth of 8.56 x1010 CFU/ml compared to two synthetic media with lactose and sucrose as carbon sources which contained 2.34 ×1010 CFU/ml and 1.19 ×1010 CFU/ml respectively. The initial pH of 6.5 and temperature of 42°C have been found to be optimum for the bacterial activities. The specific growth rate and yield coefficient were positively influenced in a significant manner by the experimental groups, except that inulin addition increased only the microbial load and specific growth rate was 0.26 hr-1 which was the same as that of control. The experimental conditions also enhanced the anti-oxidant, anti-adhesive, acidic pH tolerance abilities of S. thermophilus. S. thermophilus exhibited maximum anti-adhesive activity of 56.5% against Candida albicans at 42°C compared to its activity of 26.1% and 33.9% against Salmonella typhi and staphylococcus aureus respectively. S. thermophilus was resistant to amphotericin and omeprazole, but sensitive to amoxicillin, ampicillin and ciprofloxacin. The experimental conditions influenced the anti-pathogenic activity of S. thermophilus against Salmonella typhi positively.
Conclusion: Scale up of the production conditions would result in large scale production of highly efficient probiotic strain, to exert increased beneficial actions in human and applications in food and pharmaceutical industries.
Keywords: Probiotics, gut microbiota, Streptococcus thermophilus, skimmed milk medium, inulin, lactalbumin hydrolysate