Evaluation of Biosurfactant Production by Bacillus Species Using Glucose and Xylose as Carbon Sources.

Lignocellulosic material is one of the raw materials that can be used to reduce the cost of biosurfactant production because it is cheap, abundantly available, and contains cellulose and hemicellulose which can be hydrolyzed to glucose and xylose as carbon sources. This study aimed to evaluate biosurfactant production by Bacillus species using glucose and xylose as carbon sources, which are the most abundant sugar monomers from the hydrolysis of lignocellulosic materials. In this study, biosurfactants were produced by six bacterial isolates belonging to the Bacillus genus. The six bacterial isolates were identified molecularly through 16S rRNA sequencing. The results showed that the six bacterial isolates were identified as B. subtilis ITBCC46, B. subtilis ITBCC40, B. subtilis ITBCC31, B. siamensis ITBCC36, B. xiamenensis ITBCC43, and B. subtilis ITBCC30. All Bacillus species used in this study could be grown on glucose or xylose media. Biosurfactants produced by B. subtilis ITBCC46, B. subtilis ITBCC40, B. subtilis ITBCC31, and B. siamensis ITBCC36 could reduce surface tension below 40 mN/m (32.70 to 39.15 mN/m). All biosurfactants produced by these Bacillus species had more than 50% emulsification stability. These characteristics indicated that the biosurfactants had the desired quality.

The effect of Ca/Mg/Zn mixing ratio on the research octane number of bio-gasoline during basic soap pyrolysis.

Pyrolysis is one of the available technologies to convert oleic basic soap into gasoline-compatible fuel. In this research, the process mentioned was applied using the mixture of Ca, Mg, Zn in the production of oleic basic soap. The reactions were carried out in a batch glass reactor at atmospheric pressure at the temperature of 450 °C. Meanwhile, the basic soaps were made by reacting oleic acid mixed with metal hydroxides. The parameters observed were the Research Octane Number (RON) of bio-gasoline and the hydrocarbon content in the liquid product. The higher the octane number is, the better gasoline resists detonation and the smoother the engine runs. As observed, pyrolysis of oleic basic soap produced gasoline range hydrocarbon. GC-DHA results indicated that the highest RON (89.6) was achieved with Ca/Mg/Zn ratio of 0.15:0.85:1 (Ca-metal ratio of 0.15 mol). The products of the pyrolysis process comprised bio-hydrocarbon, solid residue, water, and gas. The bio-hydrocarbon contents were paraffin (5.9 wt%), iso-paraffin (31.3 wt%), olefin (18.5 wt%), naphthene (25.3 wt%), and aromatic compounds (15.3 wt%).

The promising performance of manganese gluconate as a liquid redox sulfur recovery agent against oxidative degradation.

This work studied the oxidative degradation performance of manganese gluconate as a liquid redox sulfur recovery (LRSR) agent. The degradation of gluconate in an aerated sulfide containing 0.1 M manganese/0.8 M gluconate/pH 13 solution was 11% in 47 h and 20% in 100 h of reaction time. With the total price of chelates being more or less comparable, these were superior to the degradation resistance of EDTA chelate in a solution of 0.1 M iron/0.2 M EDTA/pH 8 which degraded by about 30% in 47 h, and NTA in Fe-NTA (0.1 M metal/0.2 M chelate/pH 6.5), which was degraded by 40% in 100 h of reaction time. At pH of 13, 0.1 M Metal, and 0.8 M gluconate, manganese degraded gluconate more severely than iron and copper. At a lower chelate to metal molar ratio (RCM) of 2 and as well as at a lower pH of 10, the manganese gluconate degradation, expressed as relative concentration to its initial concentration, was faster than at RCM of 8 and pH of 13. All of these observations can be explained among others by the well-known Fenton reaction hydroxyl radicals mechanism as the main cause of the degradation process.

Enzyme feeding strategies for better fed-batch enzymatic hydrolysis of empty fruit bunch.

Lignin inhibitory becomes a major obstacle for enzymatic hydrolysis of empty fruit bunch conducted in high solid loading. Since current technology required high enzyme loading, surfactant application could not effectively used since it is only efficient in low enzyme loading. In addition, it will increase final operation cost. Hence, another method namely "proportional enzyme feeding" was investigated in this paper. In this method, enzyme was added to reactor proportionally to substrate addition, different from conventional method ("whole enzyme feeding") where whole enzyme was added prior to hydrolysis process started. Proportional enzyme feeding could increase enzymatic digestibility and glucose concentration up to 26% and 12% respectively, compared to whole enzyme feeding for hydrolysis duration more than 40h. If enzymatic hydrolysis was run less than 40h (25% solid loading), whole enzyme feeding is preferable.

The performance of serial bioreactors in rapid continuous production of ethanol from dilute-acid hydrolyzates using immobilized cells.

The performance of single, and series of, continuous stirred-tank (CSTBR) and fluidized-bed bioreactor (FBBR) in anaerobic continuous cultivation of glucose in defined media and dilute-acid hydrolyzates at dilution rates 0.22, 0.43, 0.65 and 0.86 h(-1) using immobilized Saccharomyces cerevisiae CBS 8066, was investigated. While the single CSTBR and FBBR could not take up more than 77% and 92% of glucose in a defined medium at dilution rate 0.86 h(-1), addition of the second bioreactor decreased the residual glucose to less than 1.1% of the incoming sugar. A similar trend was obtained in cultivation of dilute-acid hydrolyzates. A CSTBR could take up 75% and 54% of the initial fermentable sugars at dilution rates 0.43 and 0.86 h(-1), while the addition of the FBBR improved the assimilation of the sugars to 100% and 86%, respectively. The ethanol yields from the hydrolyzate were between 0.41 and 0.48 g/g in all the experiments. The specific and volumetric ethanol productivities were 1.13 g/gh and 5.98 g/Lh for the single bioreactor and 0.98 g/gh and 5.49 g/Lh for the serial bioreactor at the highest dilution rate, respectively. Glycerol was the only important by-product in terms of concentration, and yielded 0.05-0.07 g/g from the hydrolyzate. From the initial 3.98 g/L acetic acid present in the hydrolyzate, 0.1-0.8 g/L was assimilated by the cells. The yeast cells were accumulated close to the surface of the beads. While the cells had a dry-weight concentration of 129 g/L close to the surface of the beads, the concentration in the core was only 13 g/L.

Kinetic study of detoxification of dilute-acid hydrolyzates by Ca(OH)2.

Detoxification of dilute-acid hydrolyzates by addition of Ca(OH)(2) (overliming) and cultivation of the detoxified hydrolyzates by Saccharomyces cerevisiae were examined. The examined overliming involves increasing the pH of the hydrolyzates to 9, 10, 11 or 12, keeping up to 90 min at different temperatures of 30, 45 and 60 degrees C, followed by readjustment of the pH to 5. Increasing the pH, time and/or temperature resulted in more effective degradation of furans and resulted in better fermentability for both of the tested hydrolyzates, but higher loss of the sugars was observed as well. Overliming of glucose and furfural solution at pH 12 showed a rapid decrease in concentration of these chemicals followed by a slow degradation process. Therefore, a kinetic model was proposed for the detoxification, where the sugars or furans make transient complexes with calcium ions and this complex will then be converted to the degradation product. The ANOVA analysis of the model resulted in an average R(2) of 0.99 for the model fitted to all the experimental data points.