Effect of short- medium- and long-term feeding of genetically modified maize to pigs on intestinal microbiota

High throughput sequence-based analysis of the intestinal microbiota of weanling pigs fed genetically modified Bt MON810 maize for 31 days. Abstract: The objective of this study was to investigate if feeding genetically modified (GM) Bt maize had any effects on the porcine intestinal microbiota. Eighteen pigs were weaned at ~28 days, and following a 6 day acclimatization period, were assigned to diets containing either GM (Bt MON810) or non-GM isogenic parent line maize for 31 days. Effects on the porcine intestinal microbiota were assessed through culture-dependent and -independent approaches. Fecal, cecal and ileal counts of total anaerobes, Enterobacteriaceae and Lactobacillus were not significantly different between pigs fed the isogenic or Bt maize-based diets. Furthermore, high-throughput 16S rRNA gene sequencing revealed few differences in the composition of the cecal microbiota. The only differences that were observed were that pigs fed the Bt maize-based diet had higher abundance of cecal Enterobacteriaceae (0.007 vs 0.001; P <0.05), Helicobacteraceae (0.002 vs 0.0004; P gt;0.05), Helicobacter (0.002 vs 0.0004; P <0.05) and Bacteroides (0.001 vs 0.0005; P <0.05) compared to pigs fed the isogenic maize-based diet. Bt maize-fed pigs also had lower abundance of fibre-fermenting bacteria (Prevotella, Ruminococcus, Eubacterium, Faecalibacterium, Fibrobacter, Clostridium, Bacteroides and Butyrivibrio) when these were analyzed as a group (0.13 vs 0.22; P <0.05). A lower concentration of enzyme resistant starch in the Bt maize may account for some of the differences in taxonomic distribution observed within the cecal microbiota. Overall, these results indicate that Bt maize is well tolerated at the level of the porcine intestinal microbiota and provide additional data for safety assessment of Bt maize. 680.