The Energetics and Kinetics of Extracellular Polysaccharide Production From Methanol by Micro-organisms Possessing Different Pathways of C1 Assimilation
SUMMARY: Product excretion by Methylophilus sp. NCIB 12047, Pseudomonas extorquens NCIB 9399 and Pichia pastoris during growth on methanol was examined. These organisms possess the ribulose monophosphate pathway, the serine pathway and the dihydroxyacetone pathway of C1 assimilation, respectively. Only Methylophilus sp. NCIB 12047 produced significant amounts of extracellular product from methanol under conditions of nitrogen limitation in chemostat culture. This was a low-viscosity extracellular polysaccharide containing glucose and mannose in the ratio 3:1. Maximum polysaccharide production occurred under nitrogen limitation at a methanol/ammonium sulphate ratio > 10. The other two organisms responded to nitrogen limitation by increasing the rate of methanol oxidation to CO2. The maximum yield for polysaccharide production by Methylophilus sp. was 0·34 g (g oxygen)-1 and 0·30 g (g methanol)-1. The maximum specific rate of polysaccharide production was 0·18 g (g protein)-1 h-1. Methylophilus sp. grew readily under oxygen limitation and excreted an extracellular polysaccharide under these conditions. Examination of the biochemical pathways for polysaccharide production via the various C1 fixation routes indicates that the ribulose monophosphate pathway is energetically the most favourable. Polymer production by Methylophilus sp. is energetically neutral in terms of net ATP demand; however, the rate of ATP utilization for polymer production is equivalent to 65 to 80% of that required for cell production at the same growth rate. The results reported suggest that the energetic constraints imposed by the various pathways of C1 assimilation strongly influence both the rate of synthesis and the composition of exopolysaccharides produced by methylotrophs.
ChidaK.,
ShenG.,
KodamaT.,
MinodaY.1983; Acidic polysaccharide production from methane by a new methane-oxidising bacterium H2. Agricultural and Biological Chemistry 47:275–280
CrawfordR. L.,
Hanson, (editors)R. S.1984; Washington, DC: American Society for Microbiology. Microbial Growth on C, Compounds (Proceedings of 4th International Symposium).
DostalekM.,
MolinN.1975; Studies of biomass production of methanol oxidising bacteria. Edited by S R. Tannenbaum & D. I. C. Wang. Cambridge, Muss.: MIT Press. In Single Cell Protein, vol. 2, pp:395–401
DrozdJ. W.,
LintonJ. D.,
DownsJ.,
StephensonR. J.1978; An in situ assessment of the specific lysis rate in continuous cultures of Methylococcus sp; (NCIB 11083) grown on methane. FEMS Microbiology Letters 4:311–314
DrozdJ. W.,
WrenS. J.1980; Growth energetics in the production of bacterial single cell protein from methanol. Biotechnology and Bioengineering 22:353–362
GrinbergT. A.,
KosenkoL. V.,
Malashenko.R. Yu.1984; Formation of exopolysaccharide by methylotrophic microorganisms. (in Russian, English summary). Mikrobiologicheskii Zhurnal 46:22–26
HouC. T.,
LaskinA. L.,
PatelR. N.1978; Growth and polysaccharide production by Methylo-cystis parvus OBBP on methanol. Applied and Environmental Microbiology 37:800–804
HouC. T.1984; Other applied aspects of methylotrophs. Edited by C. T. Hou. Florida: CRC Press,. In Methylotrophs: Microbiology, Biochemistry and Genetics, pp:146–167
HuqM. N.,
RalphB. J.,
RickardP. A. D.1978; The extracellular polysaccharide of a methylotrophic culture. Australian Journal of Biological Science 31:311–316
JonesC. W.,
KingsburyS. A.,
DawsonM. J.1982; The partial resolution and dye-mediated reconstitution of methanol oxidase activity in Methylophilus methylotrophus. FEMS Microbiology Letters 13:195–200
KanamaraK.,
IwamuroY.,
MikamiY.,
ObiY.,
KisakiT.1982; O-2-Methyl-D-mannose in an extracellular polysaccharide from Hyphomicrobium sp. Agricultural and Biological Chemistry 46:2419–2424
LintonJ. D.,
CrippsR. E.1978; The occurrence and identification of intracellular polyglucose storage granules in Methylococcus NCIB 11083 grown in a chemostat on methane. Archives of Microbiology 117:41–48
LintonJ. D.,
AustinR. M.,
HaughD. E.1984; The kinetics and physiology of stipitatic acid and gluconate production by carbon sufficient cultures of Penicillium stipitatum growing in continuous culture. Biotechnology and Bioengineering 26:1455–1464
MeyersA. P.,
WestlakeD. J. C.1977; Fermentation process for the production of microbial biomass and a heteropolysaccharide biopolymer. GB Patent 1580439
MisakiA.,
TsuburayaY.,
KakutaM.,
TakemotaH.,
IgarashiT.,
HashimotaT.1977; Characterization of a polysaccharide produced by the methanol-assimilating bacterium. Tokyo Soda Ken-kya Hokoku 23:89–96
MorinagaY.,
HiroseY.1984; Production of metabolites by methylotrophs. In Methylotrophs: Edited by C. T. Hou. Florida: CRC Press. Microbiology, Biotechnology and Genetics, pp:146–167
The Energetics and Kinetics of Extracellular Polysaccharide Production From Methanol by Micro-organisms Possessing Different Pathways of C1 Assimilation