Dear Ifra Ghori,

The hydrophobicity (for a probiotic strian) is an index that defines the adhesion ability of a probiotic strain in the gut mucosa. Higher the percentage of hydrophobicity, higher will be the adhesion ability of the strain to the gut epithelial mucosa.

A probiotic strain has to travel through gut and therefore must resist the physiological conditions of gut (such as acidic pH and bile). The strains must resist  0.3% of bile (the normal percentage of bile in human gut). If it resists higher percentage of bile then it is much better.

My this paper may help you,

https://www.researchgate.net/publication/287207987_Probiotic_Screening_of_Lactobacilli_Isolates_from_Uttapam_Batter_Fermented_Supplementing_with_Piper_betle_L_Leaves

Regards,

A K Dubey

Article Probiotic Screening of Lactobacilli Isolates from Uttapam Ba...

While I agree with Ashwini for the hydrophobicity of probiotics, bile tolerance of probiotics is controversial. During dysbiosis in gut microbiota, level of bile tolerating microbes increased drastically while bile sensitive short chain fatty acid producing microbes like morella and lachnospira level decreases. Increase in bile tolerating bacteria induces inflammation in the patients suffering from IBD, IBS, CD while supplementing them with probioticcs and prebiotics increased the number of SCFA producing bacteria which in turn brings back gut homeostasis with respect to immunity.

Probiotics by itself acting on host mucosa and signaling through immunological and metabolic pathways is not feasible. Rather probiotics modulate gut microbiota symbiosis positively which in turn maintains gut homeostasis. Probiotics is not expected to colonize gut mucosa for long, rather its temporary stay (mostly 48 hour) brings back the distorted microbiota to normalcy which itself is self sustainable. So excess bile tolerance for longer period is not expected from probiotics.