Functional development and performance enhancement of probiotics

Abstract

Several new kinds of diseases posing serious threat to human life have developed owing to the drastic changes in living environment, eating habits, and lifestyle. Concomitantly, there has been a gradual increase in health awareness among people, and probiotics have gained much attention for its excellent health benefits. Probiotics are live microorganisms, mainly bacteria such as Lactobacillus , Lactococcus , Bifidobacterium , Leuconostoc , and Streptococcus , which benefit human health, especially the digestive system. Probiotics have been reported to improve constipation, reduce diarrhea, decrease the content of cholesterol, enhance immunity, and protect oral health. Moreover, they have been associated with anti-tumor effects and positive effects towards prevention and treatment of autism and depression. Currently, probiotics dietary supplements and non-prescription drugs are widely used in the field of medicine. With the gradual improvement in research tools, newer functions of probiotics and insights into its relationship with diseases continue to emerge. Thus, it is important to further engage in the basic research of probiotics and explore new functions in the field of disease prevention. Meanwhile, inevitably, probiotics production faces a variety of stresses from the external environment, such as acid stress caused by lactic acid accumulation in the fermentation process, freezing stress during formulation, and osmotic stresses at various production stages. These adverse conditions affect the normal metabolism and survival of strains, thus inhibiting their probiotic effects. Therefore, it is essential to improve the stress tolerance of strains and strengthen the performance of probiotics. Recent developments in biotechnology, including microbial community analysis and high throughput screening, and evolutionary techniques can improve the efficiency of strain screening. Evolutionary engineering, including mutagenesis techniques, adaptive laboratory evolution, and genome evolution, is a valuable method to promote the phenotype or physiological characteristics of strains. Moreover, using systems biology, we can examine the effects of mutant strains as probiotics and even apply inverse metabolic engineering approaches to improve microbial characteristics and get the desired phenotype. This comprehensive review describes the main methods and principles used in functional development and performance enhancement of probiotics, and summarizes their effects in the prevention and treatment of various diseases. The aim of this review is to provide an understanding of the multiple functions of probiotics and provide a perspective on the challenges faced in the probiotics industry so as to trigger development of better industrial processes for probiotics production.