The Prediction of Growth Yields in Methylotrophs

Abstract

Equations have been developed for assimilation of methane, methanol, methylamine, dimethylamine, trimethylamine, formaldehyde and formate into cell material by bacteria using the ribulose monophosphate pathway, the ribulose bisphosphate pathway and the serine pathway of carbon assimilation. The equations have been used for predicting the effect on cell yields (Y,, Yo2 and Yc0J of various P/O ratios, systems for substrate oxidation and assimilation pathways. The generalizations relating P/O ratios and cell yields, which have been used previously for such calculations, are not always applicable to methylotrophs. In particular, for the majority of methylotrophs the growth yield is determined by NAD(P)H supply as well as ATP supply, and for some methylotrophs growth yields may be exclusively NAD(P)H-limited. Because of this NAD(P)H limitation, the concept of YATP in methylotrophs should be used with extreme caution.

Dissimilation of [13C]methanol by continuous cultures of Bacillus methanolicus MGA3 at 50 °C studied by 13C NMR and isotope-ratio mass spectrometry

“…The next step was to determine whether formate could be further oxidized to CO # by an enzyme such as an NAD-dependent formate dehydrogenase (Anthony, 1978). Dissolved "$CO # or bicarbonate is usually too dilute to be detected in "$C NMR studies of aerated cell suspensions, or may only generate a very low-intensity signal (Cornish et al, 1984).…”

Determination of Growth Parameters of Methylamine-using Bacteria

“…5, and the yield and maintenance coefficients determined are given in Table 1. The yield coefficients (1 5.6 and 21.2 g dry biomass mol-l at 50 % maximum growth rate) are considerably higher than experimentally determined values reported by Goldberg et al (1976) but within the range of theoretical possibilities calculated by Anthony (1978). Goldberg et al (1976) obtained yields of 9.3 to 11.4 g mol-l on methylamine in continuous cultures at unstated relative growth rates for three Pseudomonas species known to use the serine pathway of C,-carbon assimilation.…”

“…They reported higher yields of 15.7 to 17.3 g mol-l on methanol for strains using the more efficient ribulose monophosphate assimilation pathway. The C1 -carbon assimilation pathways used by strains B6/2 and DT26 are not known, but since non-methane-using obligate methylotrophs generally have the ribulose monophosphate pathway (Anthony, 1982) it is likely that strain B6/2, at least, uses this pathway. …”

“…Bacteria able to use methylamines in aerobic environments include specialist, obligately methylotrophic bacteria able to use only Cl-compounds as sole carbon and energy sources, generalist, facultatively methylotrophic bacteria able to use C -compounds or non-C, -compounds as sole carbon and energy sources, and methazotrophic bacteria able to use methylamines as sole nitrogen sources but not as sole carbon and energy sources (Anthony, 1982). In order to study, both by computer simulations and in laboratory mixed continuous cultures, the competition by these three types of bacteria for methylamine it was first necessary to determine the growth parameters of the selected strains.…”

Energy Conservation in the Terminal Region of the Respiratory Chain of the Methylotrophic Bacterium Methylophilus methylotrophus

“…Bell [43] suggested that there may be special features related to energy conservation associated with the oxidation of substrates more highly reduced than cell material. Anthony [44] applied this idea to methanol-utilisers by suggesting that, at least for those organisms using the serine pathway for carbon assimilation, growth might be limited by the supply of NAD(P)H rather than energy; an increase in the ATP yield from methanol oxidase would therefore be of little advantage to these organisms. The same argument, however, cannot be applied to a methylotroph such as M .…”