Biotransesterification capabilities of Mucorales whole-cell lipase isolates and mutants

Abstract

In this study, enzymatic production of biodiesel (fatty acid methyl esters, FAME) from waste frying oil (WFO) was investigated using fungal whole-cell lipase as a sustainable technique. Seven Mucorales whole-cell isolates and 6 mutants were tested for WFO transesterification to produce biodiesel. All tested isolates showed positive respond to qualitative lipase and esterase activity tests. A relatively strong positive correlation was detected between quantitative lipase activity that ranged between 15.91 and 25.42 U/g and transesterification capabilities in terms of FAME that reached up to 46.35%. Two isolates that showed potent transesterification capability were identified molecularly using rRNA ITS sequences as Rhizopus americanus 2aNRC11 and Rhizopus stolonifer 1aNRC11. Mutagenic effect of ethyl methanesulfonate (EMS) improved transesterification capabilities of R. americanus 2aNRC11 mutant B and R. stolonifer 1aNRC11 mutant G by 7.89 and 11.54%, respectively, compared to their corresponding wild types. Random amplified polymorphic DNA (RAPD) analysis supported the probability of genetic mutations as the total polymorphism reached to 70.59 and 91.3% among R. stolonifer 1aNRC11 and R. americanus 2aNRC11 mutants and their corresponding wild types, respectively.