Probiotic characterization and cholesterol assimilation ability of Pichia kudriavzevii isolated from the gut of the edible freshwater snail “Pila globosa”.

Abstract

Excess cholesterol is one of the main causes of various metabolic diseases. Currently available therapeutic measures, lifestyle, and dietary interventions, as well as pharmaceutical agents, are inadequate for the regulation of cholesterol levels. Probiotic microorganisms have demonstrated the potential to lower cholesterol levels through various mechanisms, including the activity of bile salt hydrolase, production of enzyme-inhibiting compounds such as 3-hydroxy-3-methylglutaryl coenzyme A, and assimilation of cholesterol. In the present investigation a yeast culture designated as S-I, isolated from freshwater snail’s gut (Pila globosa), fulfilled probiotic attributes. The culture was found to be non-hemolytic and could tolerate a bile concentration up to 1.2%, pH 1.5–10; and temperature 42oC respectively. Additionally, 73.57% and 36.24% of S-I culture survived when exposed to the gastric environment for 90 and 180 min respectively, while 53% survived after 240 min incubation under the intestinal environment. The S-I culture could auto-aggregate (93.01%), as well as co-aggregate (77.89%) with gastrointestinal pathogens, an important property required for the probiotics to control the pathogens. The culture also inhibited C. albicans NCIM3557, E. coli NCIM3099, E. faecalis NCIM3040, S. aureus NCIM2408and P. aeruginosa NCIM2036 in-vitro. Other probiotic properties such as hydrophobicity (81%), bile salt hydrolase activity (86.30%), and tolerance to 8% NaCl (27.38%), as well as antibiotics, were found to be in favor of the S-I culture. Most importantly, S-I culture was found to assimilate 20.29% of cholesterol. Molecular characterization of this culture performed by 18S rRNA sequencing revealed that the S-I culture was Pichia kudriavzevii species with 97% similarity.