I Clostridium autoethanogenum i protein (CAP) is a new type of microbial protein produced by the fermentation of I Clostridium autoethanogenum i with carbon monoxide from steel-making waste gas [[2]]. The content of free glutamate in muscle is significant to the flavor of fish meat, and glutamine is one of the most abundant amino acids in fish muscle. Fish account for 20% of the global population's animal protein intake.