Anaerobic digestion of cotton biomass fractions: additive effects of synthetic baccillus thuringiensis (bt)-cotton derived cry 1ac protein

Rumen microorganisms may be exposed to Cry proteins (Cry 1Ac protein) from transgenic crops through animal feed, derived from Baccillus thuringiensis (Bt) crops after harvest or after post harvest processes. The methanogenic activity test and anaerobic digestion were used to investigate the effect of different concentration of Cry 1Ac on ruminants. Methanogenic activity was investigated in the presence of Cry 1Ac protein at the concentrations of 5µg, 10µg and 15 µg in 125 ml serum bottles using acetate as a substrate for three inocula. The highest cumulative methane production was 88.50 ml at 10µg Cry concentration, 67.75 ml at 5µg and 84.60 ml at 15 µg for goat, sheep and cow inoculum respectively.Anaerobic digestion was conducted at an ambient temperature range of 30±2oC using rumen fluid from the cow as inoculum in 0.5 l BA with a range of Cry 1Ac protein concentration. Methane yield ranged between 0.353 CH4m3/kgVS to 0.484 CH4m3/kgVS was obtained from cotton seed cake using the cow inoculums while the methane yield ranged between 0.325 -0.392 CH4m3/kgVS from cotton leaves using the cow inoculum. In conclusion, the present findings emphasize that, methane yield did not significantly differ between the Cry 1Ac protein and non-Cry 1Ac protein treated cotton biomass fractions and cotton seed cake (p≤0.05). This could be attributed to a biodegradation of the Cry1Ac protein during the anaerobic digestion process.