Studies On Fermentation Conditions And Properties Of Rhizopus Sp ZM-10 Lipase

Ethyl hexanoate is known as flavour and fragrance compound, and it is widely used in distilled spirit, table vinegar and sugar industries. It is the main fragrance of luzhou-flavour liquor, and the contents of ethyl hexanoat effect the quality and flavour of luzhou-flavour liquor. Lipase(Lipase EC 3.1.1.3)is a kind of triglyceride hydrolases, and it takes part in different hydrolysis and synthesis reactions as biocatalyst. Recently, lipase is widely used in abstergent, organic sythesis and food industries, and the use in flavour and fragrance industries promotes the development of lipase.In the paper, we studied the conditions of synthesis of ethyl henanoate in non-aqueous media, the fermentation contions and properties of the lipase from Rhizopus ZM-10. Primarily study results as follows:1,The conditions of synthesis of ethyl hexanoate in non-aqueous media The lipase was stable below 40℃in solvents. When the concentration of ethanol was higher than 0.2mol/L, it would inhibite the process of esterification. The activity of lipase in cyclohexane was higher than in hexane and heptane. The methods of absorbing water had no significant effect on conversion rate. So the esterification reaction was carried out in cyclohexane solvent at 35℃, with 0.2 mol/L of hexanoic acid concentration and 1︰1.3 of acid-alcohol molar ratio . Under this condition, esterification conversion rate reached 91% after incubation for14 hours.2,The studies on the components of fermentation culture and conditions for producing lipase : sucrose 3%, peptone 1%, bean powder 3%, initial pH 8.0, temperature 30℃, fermentation period 72h. Under this condition, esterification conversion rate of ethyl hexanoate was enhanced remarkably in non-aqueous media.3,The properties of lipase from Rhizopus The optimum temperature of the lipase was 25℃, and was stabe below 30℃. The lipase optimal pH was 7.0 and 8.0 .When metal ion concentration was 2mmol/L , its activity was increased with amendment of Na+,Cu2+,Fe3+,EDTA, and when metal ion concentration was 5mmol/L, all metal ion inhibited its activity in different degree except Cu2+ . The concentration of surfactants affected lipase activity, and the type of surfactants had no significant effect on lipase activity . The values of Km and Vmax were 18.2mmol/L and 625(u/L) in optimum reaction conditions.