Effects of methanol on lipases: Molecular, kinetic and process issues in the production of biodiesel

Abstract

The biotechnological production of biodiesel is based on transesterification/esterification reactions between a source of fatty acids and a short-chain alcohol, usually methanol, catalysed by enzymes belonging to the class known as lipases. Several lipases used in industrial processes, although stable in the presence of other organic solvents, are inactivated by methanol at or below the concentration optimal for biodiesel production, making it necessary to use stepwise methanol feeding or pre-treatment of the enzyme. In this review article we focus on what is currently know about methanol inactivation of lipases, a phenomenon which is not common to all lipase enzymes, with the goal of improving the biocatalytic process. We suggest that different mechanisms can lead to inactivation of different lipases, in particular substrate inhibition and protein unfolding. Attempts to improve the performances of methanol sensitive lipases by mutagenesis as well as process engineering approaches are also summarized.

Structural insights into methanol-stable variants of lipase T6 from Geobacillus stearothermophilus

“…Biodiesel comprises mono alkyl esters of long-chain fatty acids which is mainly produced by transesterification of triglycerides derived from renewable sources (e.g., plant oil or animal fat) and short-chain alcohol in a nonaqueous reaction system. Methanol is frequently used for biodiesel production due to its reactivity and low cost, and the reaction is termed as methanolysis (Al-Zuhair 2007;Lotti et al 2014;Meher et al 2006;Tan et al 2010).…”

“…facilitate the hydrolysis of the carboxyl ester bonds present in triglycerides. However, in micro-aqueous environment, they possess the ability to catalyze esterification and transesterification reactions (Gupta et al 2004;Jaeger et al 1994Jaeger et al , 1999Lotti et al 2014). The enzymatic reaction system enables the use of lowgrade and low-cost feedstock with high free fatty acids or water content (e.g., waste cooking oil or tallow).…”

“…In addition, the biocatalyst is biodegradable and when immobilized can be reused for many production cycles and can lower the operational cost of the process. However, the major drawbacks of the enzymatic system are the biocatalyst cost and its limited stability in the presence of high methanol concentrations (Al-Zuhair 2007;Bajaj et al 2010;Lotti et al 2014;Tan et al 2010). In order to achieve complete conversion of one oil molar equivalent to fatty acid methyl ester (FAME), three molar equivalents of methanol are necessary.…”

Avaliação do potencial do fungo filamentoso <i>Mucor circinelloides</i> como fonte de lipase e lipídios para a produção de biodiesel dentro do conceito de biorrefinaria

“…Lipases solúveis, imobilizadas, preparação enzimática em estado sólido (SEP) e lipases ligadas ao micélio (células íntegras) (ALGUIEIRAS; OLIVEIRA; FREIRE, 2015;LOTTI et al, 2015;ZHAO et al, 2015;TAMALAMPUDI, 2009). …”

Impact of polybasic alcohols on biocompatibility and selectivity of Penicillin G Acylase for kinetically controlled synthesis

“…Polybasic alcohols have desired biocompatibility when employed in the PGA catalyzed kinetically controlled synthesis of CEX. As monobasic alcohols have only one hydroxyl group on one end of the molecule to form hydrogen bonds with water, whereas the hydrophobic end of monobasic alcohols are exposed, which is believed to lead to deactivation of enzymes [37]. Recent studies using both FTIR and UV-V's spectroscopies suggest that a likely complex of three ethylene glycol molecules to four water molecules are formed at the maximal excess molar volume in an ethylene glycol-water mixture (EGW) [38].…”