<b>Lipase from <i>Aspergillus niger</i> obtained from mangaba residue fermentation: biochemical characterization of free and immobilized enzymes on a sol-gel matrix

Abstract

ABSTRACT. In this study, mangaba residue (seeds) was used as a substrate for Aspergillus niger lipase production by solid-state fermentation. The partially purified enzyme was efficiently immobilized in a sol-gel matrix by covalent bonding with an immobilization yield of 91.2%. The immobilized biocatalyst and free lipase had an optimum pH of 2.0 and 5.0, respectively. However, greater stability was obtained at pH 4.0 and 7.0, respectively. The biocatalysts showed stability at the optimum temperature of 55°C, where the residual activity was above 87% after 240 min., of incubation. The lower deactivation constant (k d ) and higher half-life of the immobilized biocatalyst indicated greater thermal stability than those obtained with the free enzyme. The Michaelis Constant (K m ) (77 and 115 mM for free and immobilized lipase, respectively) and maximum reaction rate (V max ) (1250 and 714 U mg -1 for free and immobilized lipase, respectively) indicated that the immobilization process reduced enzyme-substrate affinity. Regarding the operational stability, the biocatalyst showed relative activity above 50% until seven cycles of reuse in olive oil hydrolysis. This novel biocatalyst obtained from a tropical fruit residue showed biochemical characteristics that support its application in future biocatalysis studies.Keywords: fruit residue, sol-gel, biotechnology, enzyme.Lipase de Aspergillus niger obtida a partir da fermentação do resíduo de mangaba: caracterização bioquímica das enzimas livre e imobilizada em matriz de sol-gel RESUMO. Neste estudo, o resíduo de mangaba (sementes) foi utilizado como substrato para a produção de lipase de Aspergillus niger por fermentação em estado sólido. A enzima parcialmente purificada foi eficientemente imobilizada em matriz de sol-gel por ligação covalente visto que o rendimento de imobilização foi de 91,2%. O biocatalisador imobilizado e a lipase livre mostraram pH ótimo de 2,0 e 5,0, respectivamente. Entretanto, a maior estabilidade foi obtida nos pHs 4,0 e 7,0, respectivamente. Os biocatalisadores mostraram estabilidade na temperatura ótima de 55°C em que a atividade residual foi superior a 87% após 240 min., de incubação. A menor constante de desativação (k d ) e o maior tempo de meia-vida do biocatalisador imobilizados demonstraram maior estabilidade térmica do que a obtida pela enzima livre. Os parâmetros constantes de Michaelis (K m ) (77 e 115 mm, para as enzimas livre e imobilizada, respectivamente) e velocidade máxima de reação (V máx ) (1250 e 714 U mg -1 , para as enzimas livre e imobilizada, respectivamente) indicaram que o processo de imobilização reduziu a afinidade enzima-substrato. Em relação à estabilidade operacional, o biocatalisador demonstrou atividade relativa acima de 50% até sete ciclos de reutilização na hidrólise do azeite. Este novo biocatalisador, obtido a partir de um resíduo de fruta tropical, apresentou características bioquímicas que justificam sua aplicação em estudos futuros de biocatálise.Palavras-chave: resíduo de fruta, sol-gel, biotecnologia, enz...

The engineering and immobilization of penicillin G acylase onto thermo‐sensitive tri‐block copolymer system

“…PGA could be immobilized by adsorption method, cross‐linking method, and covalent bonding method . Among them, covalent binding method was favored by researchers due to strong binding force between PGA and target, abundant types of functional groups available for design, high utilization ratio, and so on …”

“…[11][12][13][14][15] Among them, covalent binding method was favored by researchers due to strong binding force between PGA and target, abundant types of functional groups available for design, high utilization ratio, and so on. [15][16][17][18][19][20] At present, the loading capacity (L), activity retention ratio (Ar), enzyme activity (Ea), response rate (Rr), and reusable stability (Rs) are main problems of immobilized PGA, because they directly affect the economic efficiency of enterprises in actual production. 21 According to reports, the structure and composition of the carrier play an important role in above performances, 22,23 so exploring and synthesizing carrier with the best suitable composition and structure have become a long-standing goal.…”

Characterisation of a “green” lipase from Aspergillus niger immobilised on polyethersulfone membranes

“…The meal, which contained 26% lipids as determined by the Soxhlet method (Instituto Adolfo Lutz, 2008), was sterilised by autoclaving at 121°C for 15 min. (Santos, Soares, Lima, & Santana, 2017).…”

“…The enzyme was obtained through solid-state fermentation of H. speciosa seeds according to Santos et al (2017) with some modifications. The fermentations were conducted in Petri dishes containing 10 g of residue (50% moisture content) and a spore suspension of A. niger of 10 5 spores g -1 at a temperature of 37°C (in triplicate).…”

“…The kinetic parameters K m and V max of the Michaelis-Menten equation (Equation 4) were determined by varying the olive oil concentration from 1 to 70% in the enzymatic hydrolysis reaction (Santos et al, 2017).…”