Correlation of methane production with physiological traits in IMS 101 grown with methylphosphonate at different temperatures.

The diazotrophic cyanobacterium has been recognized as a potentially significant contributor to aerobic methane generation via several mechanisms including the utilization of methylphophonate (MPn) as a source of phosphorus. Currently, there is no information about how environmental factors regulate methane production by . Here, we grew IMS101 at five temperatures ranging from 16 to 31°C, and found that its methane production rates increased with rising temperatures to peak (1.028 ± 0.040 nmol CH μmol POC day) at 27°C, and then declined. Its specific growth rate changed from 0.03 ± 0.01 d to 0.34 ± 0.02 d, with the optimal growth temperature identified between 27 and 31°C. Within the tested temperature range the Q for the methane production rate was 4.6 ± 0.7, indicating a high sensitivity to thermal changes. In parallel, the methane production rates showed robust positive correlations with the assimilation rates of carbon, nitrogen, and phosphorus, resulting in the methane production quotients (molar ratio of carbon, nitrogen, or phosphorus assimilated to methane produced) of 227-494 for carbon, 40-128 for nitrogen, and 1.8-3.4 for phosphorus within the tested temperature range. Based on the experimental data, we estimated that the methane released from can offset about 1% of its CO mitigation effects.