PJB-2017-298
Isolation, identification of an axenic fungal isolate of Aspergillus sp. (MBL-1511) and its subsequent improvement for enhanced extracellular lipolytic potential through monoculture fermentation
Tehreema Iftikhar, Sidra, Muhammad Ali, Muhammad Ibrahim Rajoka, Hammad Majeed and Roheena Abdullah
Abstract
The present investigation was conducted for extracellular lipases production. One hundred and forty samples of fungi were isolated from different environment and food samples. Among all the isolated cultures, an isolate obtained from chicken roasted in oil (MBL-1511) gave the highest extracellular lipase through SSF. Hyper producer strain (MBL-1511) was morphologically identified. A morphologically identified isolate of Aspergillus niger (MBL 1511) was verified by DNA barcoding marker like 18S rRNA gene sequence. The sequence of Aspergillus niger (MBL 1511) was registered with accession no. [GenBank: KP172477] in the public nucleotide library (genbank) of NCBI. The selected hyper producer of Aspergillus niger (MBL-1511) strain was subjected to physical and chemical mutagenic treatments to improve its lipolytic potential. Proximate analysis confirmed brassica meal as the best basal substrate with the lipases potential of 10.67±0.01 IU/mL (wild) and 19.58±0.04 IU/mL (mutant). The optimum conditions for the maximized extracellular lipases production were 1.0 mL inoculum at 30oC after 72 h at pH of 6.2. Finally, a potent mutant of A. niger [MBL-1511SA-4(150 min)] with an increased activity of 161 % over the wild strain was obtained when olive oil was used at 1% (v/v) concentration.
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