Lactic acid bacteria (LAB) species were widely applied in various fields and exhibited unique functions due to their metabolic properties. The motivation of this review was to systematically reveal the diversities of LAB based on their specific physiological functions during food fermentation. In detail, the potential mechanisms for LAB to improve the food flavor quality involved in carbohydrate metabolism, proteolysis and amino acid catabolism, lipolysis and fatty acid metabolism were discussed. Meanwhile, LAB species exhibited a prerequisite of food safety due to their functional roles of anti-bacterial, anti-fungal, and degradation of hazardous compounds. Besides, abiotic and biotic factors encountered during food fermentation were also summarized and discussed, and the potential adaptation mechanisms of LAB to cope with these factors were revealed. Taken together, the authors hope the findings showed in this review could provide scholars with a comprehensive understanding on diversities, physiological functions and adaptation mechanisms of LAB, and further extend the industrial functionalities of LAB species.