Bacillus stearothermophilus for thermophilic production of l-lactic acid

Abstract

A process for the continuous production of high purity L-lactic acid in a membrane bioreactor at 65 degrees C has been developed. Two different Bacillus stearothermophilus strains have been tested in batch experiments. Lactic acid yields are between 60 and more than 95% of theoretical yields. The amounts of ethanol, acetate, and formate formed varied between 0 and 0.4, 0 and 0.1, and 0 and 0.5, respectively (mol/mol glucose). All byproducts are valuable and may be separated easily by rectification of the fermentation broth. Complete cell retention enables high volumetric productivity (5 g/Lh), and a minimum of growth supplements. The high temperature of 65 degrees C allows the autoselective fermentation without problems with contamination.

A Membrane-Integrated Fermentation Reactor System: Its Effects in Reducing the Amount of Sub-Raw Materials forD-Lactic Acid Continuous Fermentation bySporolactobacillus laevolacticus

“…Comparisons between our results and those of previous studies, 6,9,10,[18][19][20][21][22][23] in which the membrane area and the working volume were described clearly so as to make it possible to calculate the index of industrial process applicability, are shown in Table 3. Our report does not show the maximum production rate or the longest culture time.…”

“…Several studies have been reported in which continuous fermentation procedures were established, 6,9,10,[18][19][20][21][22][23] but there are no report on industrialization of the continuous fermentation process, possibly due to the low performance and high cost of the previously employed separation membrane. In previous studies, performance assessment of continuous fermentation has relied on improvements in the production rate.…”

“…6,9,10,[18][19][20] On the other hand, the filtration velocity was improved by using a large separation membrane area, and a significant improvement in the production rate was reported. [21][22][23] However, in this case, the cost of the separation membrane is greater. It is important to decrease the cost of the separation membrane as much as possible if continuous fermentation technology is to be applied industrially.…”

Lignocelluloses Feedstock Biorefinery as Petrorefinery Substitutes

“…In addition, the main bottleneck during the hydrolysis of lignocellulosic feedstock by cellulases is the inhibition on cellulase by glucose and cellobiose, which remarkably slows down the rate of lignocellulosic feedstock hydrolysis [94]. Economic improvements on the process are mainly focused on increasing the lactic acid tolerance, reducing the requirements for complex and cost intensive growth supplements and products recovery [95].…”

Application of pheB as a Reporter Gene for Geobacillus spp., Enabling Qualitative Colony Screening and Quantitative Analysis of Promoter Strength

“…The activity of catechol 2,3-dioxygenase was recorded by spectrophotometric measurement of the accumulation of HMSA (ε ϭ 33 mM cm Ϫ1 ) at ϭ 375 nm. A saturating substrate concentration was determined by carrying out the assay at 55°C with a reaction mixture containing 2.9 ml of 50 mM sodium phosphate buffer (pH 7.2) and 100 l of catechol (in distilled water [dH 2 O]) in a range of 0.05 to 1 mM and preincubation for 8 min at 55°C. The reaction was initiated by adding 10 l of cleared cell lysate, with absorbance readings taken over a time course of 2 min.…”