Effects of microcystin-LR on bacterial and fungal functional genes profile in rat gut.

The short-term exposure to microcystin-LR (MC-LR, one of the most common and toxic variants generated by toxigenic cyanobacteria) induced gut dysfunction such as generation of reactive oxygen species, cell erosion and deficient intestinal absorption of nutrients. However, till now, little is known about its impact on gut microbial community, which has been considered as necessary metabolic assistant and stresses resistant entities for the host. This study was designed to reveal the shift of microbial functional genes in the gut of rat orally gavaged with MC-LR. GeoChip detected a high diversity of bacterial and fungal genes involved in basic metabolic processes and stress resistance. The results showed that the composition of functional genes was significantly changed in rat gut after one week of exposure to MC-LR, and we found some relatively enriched genes that are involved in carbon degradation including chitin, starch and limonene metabolism, and these genes were mainly derived from fungal and bacterial pathogens. In addition, we found large amounts of significantly enriched genes relevant to degradation of the specific carbon compounds, aromatics. The dysbiosis of bacterial and fungal flora gave an implication of pathogens invasion. The enriched gene functions could be linked to acute gastroenteritis induced by MC-LR.