Recent advances in lactic acid production by microbial fermentation processes

Lactic acid production from lignocellulose-derived sugars using lactic acid bacteria: Overview and limits

Polymeric materials prepared from renewable natural resources are now being accepted as “bio-based polymers”, because they are superior to the conventional petroleum-based polymers in reducing the emission of carbon dioxide. Among them, poly(L-lactide) (PLLA) prepared by fermentation and polymerization is paid an immediate attention. Although PLLA exhibits a broad range of physico-chemical properties, its thermal and mechanical properties are somewhat poorer for use as ordinary structural materials. For improving these inferior properties, a stereocomplex form consisting of PLLA and its enantiomer poly(D-lactide) (PDLA) has high potential because of showing high melting nature (230 °C). It can be formed by simple polymer blend of PLLA and PDLA or more easily with stereoblock polylactides (sb-PLA) which are PLLA/PDLA block copolymers. These novel PLA polymers, named “Neo-PLA”, can provide a wide range of properties that have never be attained with single PLLA. Neo-PLA retains sustainability or bio-based nature, because both monomers L- and D-lactic acids are manufactured from starch by fermentation. Copyright © 2006 Society of Chemical Industry

Stereocomplexed polylactides (Neo-PLA) as high-performance bio-based polymers: their formation, properties, and application

In mineral salts medium under oxygen deprivation, Corynebacterium glutamicum exhibits high productivity of l-lactic acid accompanied with succinic and acetic acids. In taking advantage of this elevated productivity, C. glutamicum was genetically modified to produce d-lactic acid. The modification involved expression of fermentative d-lactate dehydrogenase (d-LDH)-encoding genes from Escherichia coli and Lactobacillus delbrueckii in l-lactate dehydrogenase (l-LDH)-encoding ldhA-null C. glutamicum mutants to yield strains C. glutamicum ΔldhA/pCRB201 and C. glutamicum ΔldhA/pCRB204, respectively. The productivity of C. glutamicum ΔldhA/pCRB204 was fivefold higher than that of C. glutamicum ΔldhA/pCRB201. By using C. glutamicum ΔldhA/pCRB204 cells packed to a high density in mineral salts medium, up to 1,336 mM (120 g l−1) of d-lactic acid of greater than 99.9% optical purity was produced within 30 h.

Production of d -lactic acid by Corynebacterium glutamicum under oxygen deprivation

Purification and characterization of cellulase produced by Bacillus amyoliquefaciens DL-3 utilizing rice hull.

Production of D-lactic acid from defatted rice bran by simultaneous saccharification and fermentation.

Production of γ-aminobutyric acid (GABA), which shows an antihypertensive effect, from glutamate was investigated using rice germ or bran as enzyme (glutamate decarboxylase; GAD) sources. GAD activity in the rice germ was dependent on the concentrations of glutamate and pyridoxal phosphate. The maximum activity in the germ was estimated to be 8.8 μmol/min/g. By a pH-controlled batch reaction using the rice germ, we produced 29.0 g of GABA per 100 g of the germ by incubation for 6 h at 40°C, with the conversion rate of 87.9% . The rice bran was also an effective catalyst for GABA production. These results suggested that our methods are efficient for manufacturing GABA, which is useful in the development of functional foods to manage hypertension.

Enzymatic Production of γ-Aminobutyric Acid Using Rice (Oryza sativa) Germ

On the basis of growth rate at low pH, yield of lactic acid from glucose, and optical purity of lactic acid produced, we selected lactic acid bacteria favorable for production of optically pure L-lactic acid from defatted rice bran without sterilization. Of 21 strains tested, strains Nos. 13 and 16 produced 27-29kgm-3 of lactic acid with high optical purity from 100kgm-3 of unsterilized defatted rice bran in simultaneous saccharification and fermentation (SSF) with MRS medium at pH 4.5, a level at which the growth of indigenous lactic acid bacteria in defatted rice bran was suppressed. In a SSF process using strain No. 16 in which McIlvaine buffer (pH 4.5) was used instead of MRS medium, no growth of indigenous lactic acid bacteria was observed in defatted rice bran, and 28kgm-3 of lactic acid with 92% L-type content was produced from 100kgm-3 of unsterilized defatted rice bran. In SSF using McIlvaine buffer (pH 4.5), the protein fraction of defatted rice bran was found to play a significant role as a nitrogen source for the growth of lactic acid bacteria. By increasing the initial cell concentration to OD660=1.0 for SSF using strain No. 16 and McIlvaine buffer (pH 4.5), the proportion of L-lactic acid produced was enhanced to 95%.

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Production of L-Lactic Acid by Simultaneous Saccharification and Fermentation Using Unsterilized Defatted Rice Bran as a Carbon Source and Nutrient Components

On the basis of cDNA sequences, we found that the calli of rice encodes an amino acid sequence that shares 56% and 89% identity, respectively, with oryzacystatin-I and oryzacystatin-II This sequence differs from that of oryzacystatin-II in the N-terminal region (Gln7−Ala19 in the oryzacystatin-III numbering), and this region contained a glycine residue (Gly14), which is evolutionarily conserved in the cystatin superfamily We named this novel protein oryzacystatin-III Nucleotide sequencing of the 5‘-flanking region of the oryzacystatin-III gene showed that it is highly homologous to the oryzacystatin-II gene but distinct from the oryzacystatin-II locus Oryzacystatin-III inhibited papain, ficin, and human cathepsin B The inhibition constants for papain and ficin differ from those of oryzacystatin-I and -II, and cathepsin B activity is affected only by oryzacystatin-III, showing differences in the interaction of these inhibitors with enzymes These data suggest that the above three inhibitors may play u

Molecular cloning and characterization of oryzacystatin-III, a novel member of phytocystatin in rice (Oryza sativa L. japonica).

Porphyromonas gingivalis is known to be a major etiologic agent in the onset and progression of chronic periodontitis. Among various virulence factors that this bacterium produces, Arg- and Lys-spe...

Identification of proteinaceous inhibitors of a cysteine proteinase (an Arg-specific gingipain) from Porphyromonas gingivalis in rice grain, using targeted-proteomics approaches.

Sadami Ohtsubo

Papers

Production of D-lactic acid from defatted rice bran by simultaneous saccharification and fermentation.

Enzymatic Production of γ-Aminobutyric Acid Using Rice (Oryza sativa) Germ

Production of L-Lactic Acid by Simultaneous Saccharification and Fermentation Using Unsterilized Defatted Rice Bran as a Carbon Source and Nutrient Components

Molecular cloning and characterization of oryzacystatin-III, a novel member of phytocystatin in rice (Oryza sativa L. japonica).

Identification of proteinaceous inhibitors of a cysteine proteinase (an Arg-specific gingipain) from Porphyromonas gingivalis in rice grain, using targeted-proteomics approaches.