Response of methanotrophic activity to extracellular polymeric substance production and its influencing factors.

The accumulation of extracellular polymeric substance (EPS) is speculated to be related with the decrease of CH oxidation rate after a peak in long-term laboratory landfill covers and biofilters. However, few data have been reported about EPS production of methanotrophs and its feedback effects on methanotrophic activity. In this study, Methylosinus sporium was used asa model methanotroph to investigate EPS production and its influencing factors during CH oxidation. The results showed that methanotrophs could secret EPS into the habits during CH oxidation and had a negative feedback effect on CH oxidation. The EPS amount fitted well with the CH oxidation activity with the exponential model. The environmental factors such as pH, temperature, CH, O, NO-N and NH-N could affect the EPS production of methanotrophs. When pH, temperature, CH, O and N concentrations (including NO-N and NH-N) were 6.5-7.5, 30-40°C, 10-15%, 10% and 20-140mgL, respectively, the high cell growth rate and CH oxidation activity of Methylosinus sporium occurred in the media with the low EPS production, which was beneficial to sustainable and efficient CH oxidation. In practice, O-limited condition such as the O concentration of 10% might be a good way to control EPS production and enhance CH oxidation to mitigate CH emission from landfills.