Compositions and methods for mucosal delivery of agents are provided. The emulsion compositions are intended for administration to a mucosal surface, such as oral, gastrointestinal and nasal mucosa. The emulsion compositions provided contain one or more mucoadhesive proteins and an agent to be delivered. Methods for delivery of agents using the compositions provided herein are also provided.

A composition for promoting development of the intestinal tract, a composition for improving lung function or a composition for improving immune function containing a bacterium belonging to Bifidobacterium longum subsp. infantis is provided. The bacterium is preferably Bifidobacterium longum subsp. infantis M-63 (NITE BP-02623).

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.