Optimization of methane production rate can potentially decrease the operational lifetime of the landfill site and assist with better management of methane harvesting from the landfill cells. Increased moisture content in landfill cells is known to increase the rate of methane production. Several natural biopolymers can sustain moisture content in a solid matrix while providing a scaffolding for microbial communities to grow. This research examined the effect of the biopolymer, produced by Rhizobium tropici, on bench-scale methane generation from municipal solid waste. The addition of the R. tropici biopolymer increased the rate of methane production from 27% to 78% when compared to the control study for low and high concentrations of biopolymer amendment, respectively. R. tropici biopolymer shortened the lag phase by up to six days over the control, depending on the level of biopolymer amendment added to the solid waste. The mechanism appears to be facilitating biofilm formation through the combination of increased moisture retention and surface modification of the solid waste. Incorporation of biopolymer amendment in the alternative daily cover activities at commercial landfills could provide a viable approach for full scale application. Published by Elsevier B.V.