TABLE 1.

The degradation of macromolecular substances in food by lactic acid bacteria.

Substance	Metabolic Engineering works	Expanding applications in the food industry	Lactic acid bacteria strains (References)
Polysaccharides	Hydrolyze polysaccharides with α-(1→4) glycosidic bonds	Hydrolyze starch or fructan in sourdough	Weissella (Falasconi et al., 2020) Lactiplantibacillus plantarum (Oguntoyinbo and Narbad, 2012)
Proteins and related Amino acids	Heterologous expression of prtB gene encoding the protease	Effectively hydrolyze protein in milk	Enterococcus faecium (Biscola et al., 2018; Kordesedehi et al., 2018; Worsztynowicz et al., 2019)
	Different bioactive peptides and the bioactivity diversity can be increased by editing the proteolytic system of Lactococcus lactis	Improve the in vitro digestibility of protein of cereal products	Lactiplantibacillus plantarum VTT E-133328 (Coda et al., 2015)
Other non-nutritive and harmful substances		Produce urethanase-promoted EC degradation in alcohol fermentation	Oenococcus oeni, Levilactobacillus brevis, and Lactiplantibacillus plantarum (Fang et al., 2019)
		Decompose phytic acid in the fermentation process of yam-based foods	Leuconostoc lactis CCMA 0415, Lactiplantibacillus plantarum CCMA 0744 (Batista et al., 2019)
		Hydrolyze bitter peptides in cheese production	Lactobacillus helveticus (Komprda et al., 2008)