Isolation, characterization, and fermentative pattern of a novel thermotolerant Prototheca zopfii var. hydrocarbonea strain producing ethanol and CO2 from glucose at 40 degrees C.
A novel thermotolerant strain of the achlorophyllous micro-alga Prototheca was isolated from a hot spring. The isolate was found to produce an appreciable amount of ethanol and CO2 from glucose under anoxic conditions at both 25 and 40 degrees C; this type of alcohol fermentation has not yet been reported in the genus Prototheca. Moreover, it also evolved gas from sucrose after a time lag at 40 degrees C. Its taxonomic characteristics coincided with those of Prototheca zopfii var. hydrocarbonea, and phylogenetic analysis, based on a small-subunit (SSU) rDNA sequence, also revealed a close relationship between the two strains. D-lactic acid, ethanol, CO2 and a trace of acetic acid were produced from glucose, but L-lactic acid, formic acid, and H2 were not. At 25 degrees C, D-lactic acid and ethanol were produced in approximately equimolar amounts under N2/H2/CO2, whereas ethanol production was predominant under N2. More ethanol was produced at 40 degrees C than at 25 degrees C irrespective of the gas composition in the atmosphere. This is the first report on gas production from glucose and on the changes in the fermentative patterns as a function of temperature for the genus Prototheca.
Ueno
Ryohei
R
Laboratory of Marine Biochemistry, Tokyo University of Fisheries, Konan, Minato, Tokyo, 108-8477, Japan.
Urano
Naoto
N
Suzuki
Motofumi
M
Kimura
Shigeru
S
D000693:Anaerobiosis; D002245:Carbon Dioxide / Q000378:metabolism*; D004271:DNA, Fungal / Q000235:genetics; D000431:Ethanol / Q000378:metabolism*; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D008969:Molecular Sequence Data; D011525:Prototheca / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D012335:RNA, Ribosomal / Q000235:genetics; D013696:Temperature; D014871:Water Microbiology
D004271:DNA, Fungal; D012335:RNA, Ribosomal; D002245:Carbon Dioxide; D000431:Ethanol; D005947:Glucose