ABSTRACT
Bacillus sp. BC-001 was first reported as a potent thermotolerant and homofermentative strain for an industrial-scale L-lactate production. In a flask culture, this isolate fermented both glucose and sucrose to lactate with high yield (0.96 and 0.87 g/g) and productivity (2.8 and 2.6 g/L h), respectively. The higher lactate production performance was obtained in the simultaneous saccharification and fermentation of liquefied starch (150.1 g/L final titer, 0.98 g/g yield, 3.2 g/L h productivity) and the fed-batch glucose fermentation (139.9 g/L final titer, 0.96 g/g yield, 2.9 g/L h productivity). Significant increase in lactate productivity (5.5-6.1 g/L h) was obtained from the high/heavy-inoculum seed in the stirred tank fermentor. Both calcium bases and monovalent bases were successfully employed for pH control during lactate fermentation by this isolate resulting in a versatile and simple operation. By the two-phase fermentation using the high/heavy-inoculum seed of BC-001, the fermentation reproducibility was acquired toward the pilot-scale fermentors.
Subject(s)
Bacillus/metabolism , Fermentation , Lactic Acid/metabolism , Bacillus/genetics , Bacillus/growth & development , Bioreactors , Glucose/metabolism , Hydrogen-Ion Concentration , Reproducibility of ResultsABSTRACT
A Gram-stain-positive, lactic acid-producing bacterium designed strain MK21-7T, was isolated from tree bark collected from the north east of Thailand. This strain was a facultatively anaerobic spore-forming rod that was catalase-negative. It contained meso-diaminopimelic acid in the cell wall peptidoglycan and had seven isoprene units (MK-7) as the predominant menaquinone. Major fatty acids of MK21-7T were anteiso-C17â:â0, iso-C16â:â0, anteiso-C15â:â0 and C18â:â1ω9c. Polar lipids were phosphatidglycerol, diphosphatidylglycerol, an unknown phospholipid, three unknown glycolipids and an unknown lipid. The results of 16S rRNA gene sequence analysis indicated that it represented a member of the genus Sporolactobacillus. MK21-7T showed the highest 16S rRNA gene sequence similarity to Sporolactobacillus terrae NBRC 101527T with 98.4â% similarity and exhibited 97.6â% similarity with Sporolactobacillus kofuensis NRIC 0334T, 97.5â% with Sporolactobacillus laevolacticus NRIC 0361T, 97.3â% with Sporolactobacillus nakayamaesubsp.nakayamae NRIC 0347T and 97.1â% with Sporolactobacillus nakayamaesubsp.racemicus NBRC 101524T. Analysis of the phylogenetic relationship based on 16S rRNA and gyrB gene sequencing revealed that the position of MK21-7T was clearly separated from all related species of the genus Sporolactobacillus. It had low DNA-DNA relatedness (22.8-57.2â%) with S. terrae NBRC 101527T and related type strains. The DNA G+C content was 43.1 mol%. On the basis of the results of the phenotypic, genotypic and chemotaxonomic studies, MK21-7T should be classified as representing a novel species of the genus Sporolactobacillus for which the name Sporolactobacillus shoreicorticis sp. nov. is proposed. The type strain is MK21-7T (=NBRC 111517T=LMG 29111T=TISTR 2466T).
Subject(s)
Bacillales/classification , Lactic Acid , Phylogeny , Plant Bark/microbiology , Bacillales/genetics , Bacillales/isolation & purification , Bacterial Typing Techniques , Base Composition , Cell Wall/chemistry , DNA, Bacterial/genetics , Diaminopimelic Acid/chemistry , Fatty Acids/chemistry , Glycolipids/chemistry , Nucleic Acid Hybridization , Peptidoglycan/chemistry , Phospholipids/chemistry , RNA, Ribosomal, 16S/genetics , Sequence Analysis, DNA , Thailand , Vitamin K 2/analogs & derivatives , Vitamin K 2/chemistryABSTRACT
A Gram-stain-positive, catalase-positive, facultatively anaerobic, spore-forming, rod-shaped bacterium, strain NK26-11T, was isolated from soil in Thailand. This strain produced d-lactic acid from glucose homofermentatively, and grew at 20-45 °C and pH 5-8.5. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The major respiratory quinone was menaquinone 7 (MK-7), the DNA G+C content was 42.6âmol%, and the major cellular fatty acids were anteiso-C15 : 0 and anteiso-C17 : 0. On the basis of 16S rRNA gene sequences analysis, strain NK26-11T was closely related to Bacillus solimangrovi JCM 18994T (93.89 % 16S rRNA gene sequence similarity), Pullulanibacillus naganoensis LMG 12887T (93.32 %), Sporolactobacillus inulinus NRIC 1133T (92.99 %), Tuberibacillus calidus JCM 13397T (92.98 %) and Thalassobacillus devorans DSM 16966T ( < 90.93 %). Strain NK26-11T could be clearly distinguished from the closely related genera based on phenotypic characteristics and DNA G+C content, and thus represents a novel species of a new genus between the Bacillus and Sporolactobacillus cluster, for which the name Terrilactibacillus laevilacticus gen. nov., sp. nov. is proposed. The type strain of the type species is NK26-11T ( = LMG 27803T = TISTR 2241T = PCU 335T).
