Lactic acid bacteria are a kind of microorganisms that can ferment carbohydrates to produce lactic acid, and are currently widely used in the fermented food industry. In recent years, with the excellent role of lactic acid bacteria in the food industry and probiotic functions, their microbial metabolic characteristics have also attracted more attention. Lactic acid bacteria can decompose macromolecular substances in food, including degradation of indigestible polysaccharides and transformation of undesirable flavor substances. Meanwhile, they can also produce a variety of products including short-chain fatty acids, amines, bacteriocins, vitamins and exopolysaccharides during metabolism. Based on the above-mentioned metabolic characteristics, lactic acid bacteria have shown a variety of expanded applications in the food industry. On the one hand, they are used to improve the flavor of fermented foods, increase the nutrition of foods, reduce harmful substances, increase shelf life, and so on. On the other hand, they can be used as probiotics to promote health in the body. This article reviews and prospects the important metabolites in the expanded application of lactic acid bacteria from the perspective of bioengineering and biotechnology.

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By density functional theory calculations, we demonstrate that the high selectivity for H 2 permeability relative to CH 4 , CO, and CO 2 could be fine adjusted by B or N doping in porous graphene (PG), which is very useful for separation of H 2 from the mixed gases. Also, the atomically dispersed Li and Ca bindings to the polyphenylene structure are significantly enhanced by B doping. The average binding energies for fully adsorbed Li and Ca atoms on 2B-PG of 1.62 and 1.75 eV are greatly larger than 0.68 and 1.05 eV for pure PG, respectively. It is beneficial to experimental metal decoration since these values exceed the cohesive energies per atom of bulk Li and Ca. Grand canonical Monte Carlo simulations show that the high H 2 storage capacities with 6.4 wt % for Li-decorated 2B-PG and 6.8 wt % for Ca-decorated 2B-PG can be obtained at 298 K and 100 bar. Thus, PG through successful controlled synthesis and available doping technology will be expected to achieve the coming hydrogen economy.