Probiotic Characterization of Cholesterol-Lowering Saccharomyces cerevisiae Isolated from Frass of Pyrrharctia isabella Caterpillars

Cholesterol hyper-accumulation is an increasing risk factor causing cardiovascular diseases. Cardiovascular diseases are leading causes of death worldwide, accounting for 16.7 million deaths annually. An increase from 25.7 to 54.7 million cases of cardiovascular diseases is reported in India. Since 1990, changes in dietary patterns have been the major causes of this condition. However, current treatments such as statins and β-blockers are inadequate and include systemic toxicity such as stent thrombosis and chronic inflammation. Probiotics with cholesterol-lowering ability are ideal safe choices for the prevention of cardiovascular diseases. Material and Methods: The present study involved culture-dependent method for the enumeration of microorganisms from Pyrrharctia isabella. Microorganisms were isolated and purified and their morphology was studied microscopically. Strains that showed yeast morphology were selected for further probiotic characterization. These isolates were further characterized for probiotic potential based on guidelines from World Health Organization, Indian Council of Medical Research and World Gastroenterology Organisation. The present study assessed cholesterol-lowering potential of the best characterized isolate. Results and Conclusion: Culture-dependent approach resulted in the isolation of four yeast cultures from the frass of Pyrrharctia isabella caterpillars. Cultures showed antimicrobial activity and other probiotic characteristics such as resisted pH, bile and temperature, similar to the reports by Khisti et al., 2019. However, the novel strain isolated from Pyrrhactia isabella could survive high concentrations of NaCl (1.02M) with an 80.32% survival rate, showing 40.23% hydrophobicity. CP-I culture showed bile salt hydrolase activity as well as susceptibility to sulphatried, penicillin-G, tetracycline and chloramphenicol. This isolate showed the potential to decrease cholesterol levels by 9.16% under in-vitro conditions. Molecular identification of the novel isolate demonstrated that it belonged to Saccharomyces cerevisiae with 97% genetic similarity. Thus, this study demonstrated for the first-time isolation of cholesterol-lowering probiotic yeast Saccharomyces cerevisiae from caterpillar frass under in-vitro conditions.