We know there are lots of biological mechanisms that retain state at the cellular level to put it in CS-ish terms. A fraction of these mechanisms could plausibly be transmitted outside the cell (e.g., miRNA).
These mechanisms may or may not encode memories as we typically understand them, i.e., the ability to remember an event or fact, but could very plausibly shift personality, preferences, etc.
Not to mention that most neurotransmitters are produced / collected from the gut. Many seem to be produced / used as signalling molecules by gut microbiota.
These mechanisms may or may not encode memories as we typically understand them, i.e., the ability to remember an event or fact, but could very plausibly shift personality, preferences, etc.