The aim of this review was to elucidate the role of copper and iron in regulating methane (CH4) oxidation and subsequent biopolymer (i.e. polyhydroxyalkanoate [PHA]) accumulation in methanotrophic bacteria. Specifically, the review emphasizes the "copper switch mechanism" that alters CH4 oxidizing enzyme activities, that is soluble- and particulate methane monooxygenases, in type II methanotrophic bacteria. Both copper and iron are essential nutrients and reports demonstrate that addition of either can improve PHA accumulation. However, based on analyses of available data, a major knowledge gap regarding a clear understanding of the interactive effects in regulating methane monooxygenase enzyme activities/gene expressions was identified in this review.