Catabolism of mannitol in Lactococcus lactis MG1363 and a mutant defective in lactate dehydrogenase.
Mannitol metabolism in Lactococcus lactis MG1363 and in a derivative strain deficient in lactate dehydrogenase (LDH(d)) was characterized. Both strains had the ability to grow on mannitol as an energy source, although this polyol was a poorer substrate for growth than glucose. When compared to glucose, the metabolism of mannitol caused an NADH burden due to formation of an additional NADH molecule at the reaction catalysed by mannitol-1-phosphate dehydrogenase (Mtl1PDH). This resulted in a prominent accumulation of mannitol 1-phosphate (Mtl1P) both in growing and resting cells, suggesting the existence of a severe bottleneck at Mtl1PDH. Growth on mannitol induced the activity of Mtl1PDH in both the LDH(d) and MG1363 strains. The lower accumulation of Mtl1P in mannitol-grown cells when compared to glucose-grown LDH(d) cells, as monitored by in vivo (13)C-NMR, reflects this induction. A clear shift towards the production of ethanol was observed on mannitol, indicating pressure to regenerate NAD(+) when this substrate was used. A strategy to obtain a mannitol-overproducing strain is proposed.
Neves
Ana Rute
AR
Instituto de Tecnologia Quı́mica e Biológica/Universidade Nova de Lisboa, and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal1.
Ramos
Ana
A
Instituto de Tecnologia Quı́mica e Biológica/Universidade Nova de Lisboa, and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal1.
Shearman
Claire
C
Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney, Norwich NR4 7UA, UK2.
Gasson
Michael J
MJ
Institute of Food Research, Norwich Laboratory, Norwich Research Park, Colney, Norwich NR4 7UA, UK2.
Santos
Helena
H
Instituto de Tecnologia Quı́mica e Biológica/Universidade Nova de Lisboa, and Instituto de Biologia Experimental e Tecnológica, Rua da Quinta Grande, 6, Apt 127, 2780-156 Oeiras, Portugal1.
D018533:Biomass; D002247:Carbon Isotopes; D005632:Fructose / Q000378:metabolism; D005947:Glucose / Q000378:metabolism; D005988:Glyceric Acids / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D013294:Lactococcus lactis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008353:Mannitol / Q000378:metabolism*; D009154:Mutation
D002247:Carbon Isotopes; D005988:Glyceric Acids; D005632:Fructose; D008353:Mannitol; C005156:3-phosphoglycerate; D007770:L-Lactate Dehydrogenase; D005947:Glucose