Characteristic Type 1 Type 2
Cell morphology Short rods, usually occur singly; some cocci or ellipsoids Crescent-shaped rods, rods, pear-shaped cells, sometimes occur in rosettes
G+C content of DNA (mol%) 49-60 62-67
Nitrogen fixation No Yes
RuMP pathway present Yes No
Serine pathway No Yes
Table 1: Differential biochemical and physiological characteristics of type I and II methanotrophic bacteria [51].