The growing global demand for nutritional protein means that a sustainable source such as Single Cell Protein from Methylococcus capsulatus (Bath) can become a potential replacement for fishmeal and other animal feeds. Improving biomass concentrations using statistical optimization during synergistic fermentations with a mixed consortium of the three heterotrophic bacteria Alcaligenes acidovorans, Aneurinibacillus danicus, and Brevibacillus sp. can increase the feasibility of the industrial process. The medium components Mg2+, Ca2+, Fe3+, Cu2+, PO42-, NO3-, MoO42-, trace metals, and process temperature were screened using a two-level Plackett-Burman Design in shake flasks which resulted in Cu2+ being the only significant factor. The optimum level of CuSO4.5H2O was found to be 40 μM using One Factor Response Surface Methodology, which was three times higher than the typical values of Cu2+ used previously. These combined strategies led to a 265% increase in biomass, with final cell concentration of 10.3 g/L, up from 2.8 g/L in fed batch fermentations over 48 hours. The heterotrophic bacteria did not grow on NMS or methane but increased biomass concentration when added to M. capsulatus (Bath) cultures.