Evaluation of solvent system for the enzymatic synthesis of ethanol-based biodiesel from sludge palm oil (SPO)

Identification, Characterization, and Computer-Aided Rational Design of a Novel Thermophilic Esterase from Geobacillus subterraneus, and Application in the Synthesis of Cinnamyl Acetate

Investigation of a novel thermophilic esterase gene from Geobacillus subterraneus DSMZ 13552 indicated a high amino acid sequence similarity of 25.9% to a reported esterase from Geobacillus sp. A strategy that integrated computer-aided rational design tools was developed to select mutation sites. Six mutants were selected from four criteria based on the simulated saturation mutation (including 19 amino acid residues) results. Of these, the mutants Q78Y and G119A were found to retain 87% and 27% activity after incubation at 70 °C for 20 min, compared with the 19% activity for the wild type. Subsequently, a double-point mutant (Q78Y/G119A) was obtained and identified with optimal temperature increase from 65 to 70 °C and a 41.51% decrease in Km. The obtained T1/2 values of 42.2 min (70 °C) and 16.9 min (75 °C) for Q78Y/G119A showed increases of 340% and 412% compared with that in the wild type. Q78Y/G119A was then employed as a biocatalyst to synthesize cinnamyl acetate, for which the conversion rate reached 99.40% with 0.3 M cinnamyl alcohol at 60 °C. The results validated the enhanced enzymatic properties of the mutant and indicated better prospects for industrial application as compared to that in the wild type. This study reported a method by which an enzyme could evolve to achieve enhanced thermostability, thereby increasing its potential for industrial applications, which could also be expanded to other esterases.

Reduction in Free Fatty Acid Concentration in Sludge Palm Oil Using Heterogeneous and Homogeneous Catalysis: Process Optimization, and Reusable Heterogeneous Catalysts

Acid catalysts including Amberlyst 15 and sulfuric acid were used for heterogeneous and homogeneous catalyst reactions respectively, to reduce high free fatty acid (FFA) in sludge palm oil (SPO) using an esterification process. The goal of this research was to reduce high FFA content in SPO to less than 1 wt.% FFA so that it can be employed as a raw material in a transesterification process to produce biodiesel. Amberlyst 15 is an eco-friendly catalyst with many benefits, such as being reusable and generating non-toxic waste after reactions, compared to homogeneous catalysts, although the reaction time of the homogeneous catalyst was faster than the heterogeneous catalytic reaction. Therefore, esterification reactions with a heterogeneous and homogeneous catalytic reaction were carried out to examine conversion of FFA. The heterogeneous catalytic reaction decreased the FFA content from 89.16 wt.% to 1.26 wt.% under the recommended conditions of 44.7 wt.% methanol, 38.6 wt.% Amberlyst 15 catalyst loading, and 360 min reaction time. For homogeneous catalytic reaction, the FFA content of 1.03 wt.% was achieved under the recommended conditions of 58.4 wt.% methanol, 16.8 wt.% sulfuric acid, and 79.7 min reaction time. Furthermore, the results of the reusability research demonstrate that the heterogeneous catalyst may be reused for at least nine cycles. This research showed the promising potential of using SPO non-edible oil for biodiesel production by employing an eco-friendly heterogeneous catalyst for cost-effective environmental remediation.

Immobilization of Lipozyme TL 100L for methyl esterification of soybean oil deodorizer distillate

An immobilization method for binding cross-linked enzyme aggregates of Lipozyme TL 100L on macroporous resin NKA (CLEA-TLL@NKA) was developed in this study. The esterification activity of CLEA-TLL@NKA reached 6.4 U/mg. The surface structure of immobilized lipase was characterized by scanning electron microscopy. Methyl esterification reaction of soybean oil deodorizer distillate (SODD) was catalyzed by CLEA-TLL@NKA, which the conversion rate reached 98% and its activity retained over 90% after 20 batches of reaction. Compared with the commercial enzyme Lipozyme TLIM, half-life (t _1/2) of CLEA-TLL@NKA increased by 25 times and the catalytic activity increased by approximate 10 times. Thus, CLEA-TLL@NKA had high catalytic activity, good operational stability, and potential industrial application in the field of oil processing.

A novel process for biodiesel production from sludge palm oil

Typically, sludge palm oil (SPO) which discharged from the palm oil refining process, is a low cost material of potential value, due to its high free fatty acid content. Accordingly, there is potential for upgrading low grade oil into valuable biofuel. In this work, we present a novel method for biodiesel production from SPO. The process consists of two steps (i) free fatty acid (FFA) extraction (ii) enzymatic esterification. Firstly, SPO was saponified by hydroalcoholic solution into soap and glycerol. Secondly, the FFAs obtained were further converted into biodiesel via enzymatic esterification catalyzed by immobilised alginate-PVA lipase beads.

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Biodiesel production from sludge palm oil could be completed.

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A modified fatty acid extraction was used for SPO fatty acid preparation.

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Immobilised alginate-PVA lipase beads were used as biocatalyst for esterification reaction.

Biochemical profiles of two thermostable and organic solvent-tolerant esterases derived from a compost metagenome

Owing to the functional versatility and potential applications in industry, interest in lipolytic enzymes tolerant to organic solvents is increasing. In this study, functional screening of a compost soil metagenome resulted in identification of two lipolytic genes, est1 and est2, encoding 270 and 389 amino acids, respectively. The two genes were heterologously expressed and characterized. Est1 and Est2 are thermostable enzymes with optimal enzyme activities at 80 and 70 °C, respectively. A second-order rotatable design, which allows establishing the relationship between multiple variables with the obtained responses, was used to explore the combined effects of temperature and pH on esterase stability. The response curve indicated that Est1, and particularly Est2, retained high stability within a broad range of temperature and pH values. Furthermore, the effects of organic solvents on Est1 and Est2 activities and stabilities were assessed. Notably, Est2 activity was significantly enhanced (two- to tenfold) in the presence of ethanol, methanol, isopropanol, and 1-propanol over a concentration range between 6 and 30% (v/v). For the short-term stability (2 h of incubation), Est2 exhibited high tolerance against 60% (v/v) of ethanol, methanol, isopropanol, DMSO, and acetone, while Est1 activity resisted these solvents only at lower concentrations (below 30%, v/v). Est2 also displayed high stability towards some water-immiscible organic solvents, such as ethyl acetate, diethyl ether, and toluene. With respect to long-term stability, Est2 retained most of its activity after 26 days of incubation in the presence of 30% (v/v) ethanol, methanol, isopropanol, DMSO, or acetone. All of these features indicate that Est1 and Est2 possess application potential.

Whole-Cell Biocatalytic Synthesis of Cinnamyl Acetate with a Novel Esterase from the DNA Library of Acinetobacter hemolyticus

Cinnamyl acetate has a wide application in the flavor and fragrance industry because of its sweet, balsamic, and floral odor. Up to now, lipases have been mainly used in enzyme-mediated synthesis of cinnamyl acetate, whereas esterases are used in only a few cases. Moreover, the use of purified enzymes is often a disadvantage, which leads to increases of the production costs. In this paper, a genomic DNA library of Acinetobacter hemolyticus was constructed, and a novel esterase (EstK1) was identified. After expression in Escherichia coli, the whole-cell catalyst of EstK1 displayed high transesterification activity to produce cinnamyl acetate in nonaqueous systems. Furthermore, under optimal conditions (vinyl acetate as acyl donor, isooctane as solvent, molar ratio 1:4, temperature 40 °C), the conversion ratio of cinnamyl alcohol could be up to 94.1% at 1 h, and it reached an even higher level (97.1%) at 2 h.

Enzymatic transesterification for biodiesel production: a comprehensive review

Biodiesel catalyzed by enzyme is affected by many factors. This review will critically discuss the three major components of enzymatic production of biodiesel and the methods used to improve the reaction.

Synthesis of benzyl cinnamate by enzymatic esterification of cinnamic acid

In this study, lipase catalysis was successfully applied in synthesis of benzyl cinnamate through esterification of cinnamic acid with benzyl alcohol. Lipozyme TLIM was found to be more efficient for catalyzing this reaction than Novozym 435. In order to increase the yield of benzyl cinnamate, several media, including acetone, trichloromethane, methylbenzene, and isooctane, were used in this reaction. The reaction showed a high yield using isooctane as medium. Furthermore, the effects of several parameters such as water activity, reaction temperature, etc, on this reaction were analyzed. It was pointed out that too much benzyl alcohol would inhibit lipase activity. Under the optimum conditions, lipase-catalyzed synthesis of benzyl cinnamate gave a maximum yield of 97.3%. Besides, reusable experiment of enzyme demonstrated that Lipozyme TLIM retained 63% of its initial activity after three cycles. These results were of general interest for developing industrial processes for the preparation of benzyl cinnamate.

Enzymatic biodiesel synthesis from yeast oil using immobilized recombinant Rhizopus oryzae lipase

The recombinant Rhizopus oryzae lipase (1-3 positional selective), immobilized on Relizyme OD403, has been applied to the production of biodiesel using single cell oil from Candida sp. LEB-M3 growing on glycerol from biodiesel process. The composition of microbial oil is quite similar in terms of saponifiable lipids than olive oil, although with a higher amount of saturated fatty acids. The reaction was carried out in a solvent system, and n-hexane showed the best performance in terms of yield and easy recovery. The strategy selected for acyl acceptor addition was a stepwise methanol addition using crude and neutralized single cell oil, olive oil and oleic acid as substrates. A FAMEs yield of 40.6% was obtained with microbial oils lower than olive oil 54.3%. Finally in terms of stability, only a lost about 30% after 6 reutilizations were achieved.