Genta Kobayashi

Biodiesel production from crude palm oil and evaluation of butanol extraction and fuel properties

Three principal variables, molar ratio of methanol to oil, amount of catalyst, and reaction temperature, affecting the yield of acid-catalyzed production of methyl ester (biodiesel) from crude palm oil were investigated. The biodiesel was then used as an extractant in batch and continuous acetone–butanol–ethanol fermentation, and its fuel properties and that of the biodiesel–ABE product mix extracted from the batch culture analyzed. The optimized variables, 40:1 methanol/oil (mol/mol) with 5% H2S04 (vol/wt) reacted at 95°C for 9 h, gave a maximum ester yield of 97%. Biodiesel preferentially extracted butanol, and enhanced its production in the batch culture from 10 to 12 g l−1. The fuel properties of biodiesel and the biodiesel–ABE mix were comparable to that of No.2 diesel, but their cetane numbers and the boiling points of the 90% fractions were higher. Therefore, they could serve as efficient No. 2 diesel substitutes. The biodiesel–ABE mixture had the highest cetane number.

High butanol production by Clostridium saccharoperbutylacetonicum N1-4 in fed-batch culture with pH-Stat continuous butyric acid and glucose feeding method.

A pH-stat fed-batch culture by feeding butyric acid and glucose has been studied in an acetone-butanol-ethanol (ABE) fermentation using Clostridium saccharoperbutylacetonicum N1-4. The specific butanol production rate increased from 0.10 g-butanol/g-cells/h with no feeding of butyric acid to 0.42 g-butanol/g-cells/h with 5.0 g/l butyric acid. The pH value in broth decreases with butyric acid production during acidogenesis, and then butyric acid reutilization and butanol production result in a pH increase during solventogensis. The pH-stat fed-batch culture was performed to maintain a constant pH and butyric acid concentration in the culture broth, but feeding only butyric acid could not support butyric acid utilization and butanol production. Subsequently, when a mixture of butyric acid and glucose was fed, butyric acid was utilized and butanol was produced. To investigate the effect of the feeding ratio of butyric acid to glucose (B/G ratio), several B/G ratio solutions were fed. The maximum butanol production was 16 g/l and the residual glucose concentration in broth was very low at a B/G ratio of 1.4. Moreover, yields of butanol in relation to cell mass and glucose utilization were 54% and 72% higher in pH-stat fed-batch culture with butyric acid than that of conventional batch culture, respectively.

Extractive acetone-butanol-ethanol fermentation using methylated crude palm oil as extractant in batch culture of Clostridium saccharoperbutylacetonicum N1-4 (ATCC 13564)

The possibility of employing methylated crude palm oil (CPOE) as an extraction solvent to reduce end-product inhibition and to enhance solvent productivity in acetone-butanol-ethanol (ABE) fermentation was evaluated using oleyl alcohol as the standard butanol extractant. Fermentation was carried out at an initial glucose concentration of 90 g/l. CPOE did not inhibit the growth of the fermentative organism. Without solvent extraction, butanol production ceased after 30 h at a concentration of 15.4 g/l limiting cell growth to 3.98 g/l and glucose consumption to 62%. Applying CPOE as the extraction solvent, about 47% of the total butanol produced was extracted, glucose consumption was increased to 83% and relatively high glucose consumption rates and solvent productivities were obtained. Butanol production increased to 20.9 g/l; total ABE solvents and yield also increased from 21.2 g/l and 38% (in conventional fermentation) to 29.8 g/l and 40.4%, respectively.

Identification and production of a bacteriocin from Enterococcus mundtii QU 2 isolated from soybean.

Aims:  Identification of the bacteriocin produced by Enterococcus mundtii QU 2 newly isolated from soybean and fermentative production of the bacteriocin.

Batch culture growth model for lactate fermentation

Abstract l -Lactate fermentation using Streptococcus sp. IO-1 had a typical end product inhibition. By numerical analysis of fermentation results of the batch culture of this microorganism, it was found that the specific rates for cell growth, substrate consumption, and product formation were clearly expressed by the end product inhibition formulae. All constants for those formulae were calculated from the fermentation results. A mathematical growth model for batch culture of this microorganism was constructed. Computer simulation was done using this mathematical model. By the simulation work, the batch culture growth which expressed by the mathematical model with a ratio of sterile cells formed to total cell population measured by O.D. (α) gave satisfactory approximation to the observed results. Comparisons between computer simulation and fermentation results showed that cell growth at the beginning after lag phase was expressed by the exponential function without α to last for almost the same number of hours in any operation and sterile cell formation started with a constant α. Thus the microorganism growth should be classified into three phases; the lag phase, exponential growth phase without sterile cell formation, and exponential phase with sterile cell formation instead of the conventional classification; lag, exponential growth, linear growth, stationary, and death phases. In all of these phases except lag phase, cell growth is regulated by the end product concentration.

Membrane-assisted extractive butanol fermentation by Clostridium saccharoperbutylacetonicum N1-4 with 1-dodecanol as the extractant

A polytetrafluoroethylene (PTFE) membrane was used in membrane-assisted extractive (MAE) fermentation of acetone-butanol-ethanol (ABE) by Clostridium saccharoperbutylacetonicum N1-4. The growth inhibition effects of 1-dodecanol, which has a high partition coefficient for butanol, can be prevented by employing 1-dodecanol as an extractant when using a PTFE membrane. Compared to conventional fermentation, MAE-ABE fermentation with 1-dodecanol decreased butanol inhibition and increased glucose consumption from 59.4 to 86.0 g/L, and total butanol production increased from 16.0 to 20.1g/L. The maximum butanol production rate increased from 0.817 to 0.979 g/L/h. The butanol productivity per membrane area was remarkably high with this system, i.e., 78.6g/L/h/m(2). Therefore, it is expected that this MAE fermentation system can achieve footprint downsizing.

Breeding of a low pyruvate-producing sake yeast by isolation of a mutant resistant to ethyl α-transcyanocinnamate, an inhibitor of mitochondrial pyruvate transport.

Pyruvate is the key substance controlling the formation of diacetyl, acetaldehyde, and acetate during alcoholic fermentation. Here we report the breeding of a low pyruvate-producing sake yeast by isolation of a mutant resistant to ethyl α-transcyanocinnamate, an inhibitor of mitochondrial pyruvate transport. Mitochondrial function was involved in resistance to this substance and in the production of pyruvate by the mutants.

Computer simulation for l-lactate batch process employing Lactococcus lactis IO-1

Abstract l -lactate production employing Lactococcus lactis IO-1 demonstrated a typical end product inhibition. By numerical analysis results of the batch culture of this microorganism, the specific rates for cell growth, substrate consumption and product formation were clearly expressed by the end product inhibition formulae. All constants for those formulae were determined by process results. A mathematical model for batch culture growth of this microorganism in which the newly defined term α, a ratio of sterile cell formed to total cell population measured by optical absorbance was used, was constructed. By using this model, computer simulation was carried out and the batch culture growth gave satisfactory approximation to the observed results on the viable cell basis. However, the model gave a deviation from the observed results at the end phase of the growth. Further experiments showed that LDH activity in the solution, the key enzyme, decreased with a constant decreasing rate which is smaller than α. Simulation program using enzyme decreasing rate gave perfect results that agreed with the observed results for the whole batch.

Distribution of virulence markers among Vibrio vulnificus isolates of clinical and environmental origin and regional characteristics in Japan.

Background Vibrio vulnificus is an opportunistic human pathogen that is widely distributed in estuarine environments and is capable of causing necrotizing fasciitis and sepsis. In Japan, based on epidemiological research, the incidences of V. vulnificus were concentrated in Kyusyu, mainly in coastal areas of the Ariake Sea. To examine the virulence potential, various genotyping methods have recently been developed. This study aimed to investigate the distribution of virulence markers among V. vulnificus isolates of clinical and environmental origin in three coastal areas with different infection incidences and to determine whether these isolates have the siderophore encoding gene viuB. Methodology/Principal Findings We examined the distribution of genotypes of the 16S ribosomal ribonucleic acid (rRNA) gene, vvhA, vcg, and capsular polysaccharide (CPS), and the presence of viuB in 156 isolates collected from patients and environmental samples in Japan. The environmental samples were collected from three coastal areas: the Ariake Sea, Ise & Mikawa Bay, and Karatsu Bay. The results showed disparity in the ratios of genotypes depending on the sample origins. V. vulnificus isolates obtained from patients were classified into the clinical type for all genotypes. In the environmental isolates, the ratios of the clinical type for genotypes of the 16S rRNA gene, vvhA, and vcg were in the order of the Ariake Sea>Ise & Mikawa Bay>Karatsu Bay. Meanwhile, CPS analysis showed no significant difference. Most isolates possessed viuB. Conclusions Many V. vulnificus belonging to the clinical type existed in the Ariake Sea. Three coastal areas with different infection incidences showed distinct ratios of genotypes. This may indicate that the distribution of clinical isolates correlates with the incidence of V. vulnificus infection.

Computer simulation of l-lactate batch fermentation applying the enzyme inactivation scheme

Abstract In our previous work, a batch culture growth model for Lactococcus lactis IO-1 was introduced, but this model gave a deviation from the observed results at the end phase of the fermentation. In this experiment, we found that LDH activity in broth, the key enzyme of this fermentation, decreased with a constant decreasing rate smaller than α, the rate of sterile cell formation. Simulation program using this decreasing rate gave perfect results that agreed with the observed results for the whole phase of the fermentation.