Microbial pathways of fish spoilage and nucleotide catabolism:

• Streptococcus cremoris (Lactococcus lactis subsp. cremoris) is a dairy lactic starter culture.
• Shewanella putrefaciens is a dominant psychrotrophic marine spoilage bacterium. It degrades post-mortem nucleotides (ATP $\to$ ADP $\to$ AMP $\to$ IMP $\to$ inosine $\to$ hypoxanthine), leading to progressive accumulation of hypoxanthine which imparts a pronounced bitter off-flavor, while also reducing TMAO to fishy TMA.
• Paraburkholderia fungorum is an environmental soil bacterium.
• While S. frigidimarina is cold-adapted, S. putrefaciens is the primary recognized spoilage agent responsible for intense hypoxanthine off-flavor.