The present invention provides a method of controlling growth of unwanted microorganisms by limiting their access to manganese. More specifically, the present invention provides a method of inhibiting or delaying growth of yeast and mold by reducing the manganese concentration in a product which is preferably a food product. The invention also provides manganese scavengers and uses thereof to inhibit or delay fungal growth.

A method of fixating and stabilizing nitric oxide metabolites within fermented natural substance according to an embodiment of the present disclosure includes adding a fermentative strain to nitrogen-containing natural substance and carrying out fermentation. The fermentation efficiency is maximized by optimizing the fermentation conditions so that the productivity of nitric oxide metabolites is significantly improved. Thus, eating a fermented natural substance in which nitric oxide metabolites are fixated and stabilized by the method of the present invention would be helpful for maintaining the homeostasis of human body, in which nitric oxide synthase is either absent or insufficient, based on vasodilation and activation of a neurotransmitter and immune function as medical efficacy of nitric oxide.