Effect of process parameters on lipase production by Candida cylindracea in stirred tank bioreactor using renewable palm oil mill effluent based medium

Scale-up Lipase Production and Development of Methanol Tolerant Whole-Cell Biocatalyst from Magnusiomyces spicifer SPB2 in Stirred-Tank Bioreactor and Its Application for Biodiesel Production

This study aimed to economically develop the yeast whole-cell biocatalyst from the lipase-secreting Magnusiomyces spicifer SPB2 to serve green biodiesel production. The scaled-up productions of lipases were optimized using a 5-L stirred-tank bioreactor. The maximum extracellular lipase and cell-bound lipase (CBL) yields of 1189.65 U/L and 5603.74 U/L were achieved at 24 h and 60 h, respectively, in the modified IMY medium (pH 5.0) containing 2% of soybean oil as a carbon source and 0.2% Gum Arabic as an emulsifying agent. The optimized cultivation was initiated with an inoculum size of 1 × 107 cells/mL and conducted under an aeration rate of 0.75 vvm with an agitation speed of 400 rpm. The obtained whole-cell biocatalyst of M. spicifer SPB2 was applied to catalyze the transesterification reaction using palm oil and methanol as substrates. The greatest yield of 97.93% fatty acid methyl ester (FAME) was reached at 72 h using a palm oil/methanol ratio of 1:7, indicating high methanol stability of the biocatalyst. Moreover, substrate homogenization accelerated the reaction to achieve FAME production of 97.01% at 48 h and remained stable afterwards. Without homogenization, the highest FAME of 98.20% was obtained at 60 h. The whole-cell biocatalyst prepared from lipase-secreting M. spicifer SPB2 at an up-scaled level greatly enhanced efficiency and feasibility for commercial biodiesel production through a green conversion process.

Holistic process evaluation of non-conventional palm oil mill effluent (POME) treatment technologies: A conceptual and comparative review

Thriving oil palm agroindustry comes at a price of voluminous waste generation, with palm oil mill effluent (POME) as the most cumbersome waste due to its liquid state, high strength, and great discharge volume. In view of incompetent conventional ponding treatment, a voluminous number of publications on non-conventional POME treatments is filed in the Scopus database, mainly working on alternative or polishing POME treatments. In dearth of such comprehensive review, all the non-conventional POME treatments are rigorously reviewed in a conceptual and comparative manner. Herein, non-conventional POME treatments are sorted into the five major routes, viz. biological (bioconversions - aerobic/anaerobic biodegradation), physical (flotation & membrane filtration), chemical (Fenton oxidation), physicochemical (photooxidation, steam reforming, coagulation-flocculation, adsorption, & ultrasonication), and bioelectrochemical (microbial fuel cell) pathways. For aforementioned treatments, the constraints, pros, and cons are qualitatively and quantitatively (with compiled performance data) detailed to indicate their process maturity. Authors recommended (i) bioconversions, adsorption, and steam reforming as primary treatments, (ii) flotation and ultrasonication as pretreatments, (iii) Fenton oxidation, photooxidation, and membrane filtration as polishing treatments, and (iv) microbial fuel cell and coagulation-flocculation as pretreatment or polishing treatment. Life cycle assessments are required to evaluate the environmental, economic, and energy aspects of each process.

Immobilisation of lipase enzyme onto bacterial magnetosomes for stain removal

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Lipase was immobilized on magnetosome via glutaraldehyde, confirmed in FTIR and SEM.

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Release of p-nitro phenol confirmed the enzyme activity of immobilize lipase (88 %).

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The optimal pH (7) and temperature (40 °C) was standardised for activity.

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The immobilized lipase stored at 4 °C retained higher activity (87 %) than free lipase after 30 days.

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Immobilized lipase removed vegetable oil stain, better cleaning efficiency than free lipase.

Lipase was immobilized onto bacterial magnetosomes using glutaraldehyde cross-linking and confirmed by Fourier transform infrared spectrometry (FT-IR) and Scanning electron microscopy (SEM). Enzyme activity of immobilised lipase as well as free lipase was estimated by the release of p-nitro phenol due to the hydrolysis of p-nitro phenyl acetate (pNPA). The immobilisation yield of lipase onto magnetosome was found to be 88 %. The optimal pH (7) and temperature (40 °C) for activity was standardised and found to be similar to free lipase. The stored immobilized lipase maintained higher activity even after 30 days at a temperature of 4 °C whereas compared to free lipase. Immobilized lipase found to have removed vegetable oil stain and showed higher cleaning efficiency when compared to free lipase. The results suggest that bacterial magnetosome displays great potential as a support material for the immobilization of industrial enzymes such as lipase.

Δ12 fatty acid desaturase gene from Geotrichum candidum in cheese: molecular cloning and functional characterization

Soft cheese with white rind lacks essential fatty acids (EFAs), and as a result its long-term consumption may lead to various kinds of cardiovascular and cerebrovascular diseases, such as hyperlipidemia, hypertension, and atherosclerosis. Geotrichum candidum is a dimorphic yeast that plays an important role in the ripening of mold cheese. A gene coding for Δ12 fatty acid desaturase, a critical bifunctional enzyme desaturating oleic acid (OA) and linoleic acid (LA) to produce LA and α-linolenic acid (ALA), respectively, was isolated from G. candidum, and then cloned and heterologously expressed in Saccharomyces cerevisiae. This gene, named GcFADS12, had an open reading frame of 1257 bp and codes for a protein of 419 amino acids with a predicted molecular mass of 47.5 kDa. Characterization showed that GcFADS12 had the ability to convert OA to LA and LA to ALA, and the conversion rates for OA and LA were 20.40 ± 0.66% and 6.40 ± 0.57%, respectively. We also found that the protein product of GcFADS12 catalyzes the conversion of the intermediate product (LA) to ALA by addition of OA as the sole substrate. The catalytic activity of GcFADS12 on OA and LA was unaffected by fatty acid concentrations. Kinetic analysis revealed that GcFADS12 had stronger affinity for the OA than for the LA substrate. This study offers a solid basis for improving the production of EFAs by G. candidum in cheese.

Silk-Cocoon Matrix Immobilized Lipase Catalyzed Transesterification of Sunflower Oil for Production of Biodiesel

Biodiesel from sunflower oil using lipase chemically immobilized on silk-cocoon matrix in a packed-bed bioreactor was investigated. The immobilization was demonstrated by field-emission scanning electron microscopy and activity study. The lipase loading was 738.74 U (~0.01 g lipase powder)/g-lipase-immobilized matrix. The Km (Michaelis-Menten constant) of the free and the immobilized lipase was 451.26 μM and 257.26 μM, respectively. Low Km value of the immobilized lipase is attributed to the hydrophobic nature of the matrix that facilitated the substrate diffusion to the enzyme surface. The biodiesel yield of 81.62% was obtained at 48 hours reaction time, 6 : 1 methanol : oil ratio (v/v), and 30°C. The immobilized lipase showed high operational stability at 30°C. The substrate conversion was only marginally decreased till third cycle (each of 48 hours duration) of the reaction since less than even 5% of the original activity was decreased in each of the second and third cycle. The findings demonstrated the potential of the silk-cocoon as lipase immobilization matrix for industrial production of biodiesel.

Acid lipase from Candida viswanathii: production, biochemical properties, and potential application

Influences of environmental variables and emulsifiers on lipase production of a Candida viswanathii strain were investigated. The highest lipase activity (101.1 U) was observed at 210 rpm, pH 6.0, and 27.5°C. Other fermentation parameters analyzed showed considerable rates of biomass yield (Y L/S = 1.381 g/g), lipase yield (Y L/S = 6.892 U/g), and biomass productivity (P X = 0.282 g/h). Addition of soybean lecithin increased lipase production in 1.45-fold, presenting lipase yield (Y L/S ) of 10.061 U/g. Crude lipase presented optimal activity at acid pH of 3.5, suggesting a new lipolytic enzyme for this genus and yeast in general. In addition, crude lipase presented high stability in acid conditions and temperature between 40 and 45°C, after 24 h of incubation in these temperatures. Lipase remained active in the presence of organic solvents maintaining above 80% activity in DMSO, methanol, acetonitrile, ethanol, acetone, 1-propanol, isopropanol, and 2-propanol. Effectiveness for the hydrolysis of a wide range of natural triglycerides suggests that this new acid lipase has high potential application in the oleochemical and food industries for hydrolysis and/or modification of triacylglycerols to improve the nutritional properties.