Isolation and Screening of Amylase from Moulds Associated with the Spoilage of Some Fermented Cereal Foods

Abstract

Aims: The aim of the study is to isolate molds from spoilt samples of three fermented cereal foods (ogi, eko, pap) and screen the mold for amylase prodn. Study Design: Primary screening for amylase prodn. by the mold isolates was detd. on starch agar. Isolates having the widest zones of hydrolysis were further screened by Solid state fermn. [SSF] Methodol.: Molds were isolated on Sabouraud Dextrose Agar [SDA] incubated at 28 ± 2° for 72h and identified by std. microbiol. methods. Screening of molds for amylase activity was detd. on starch agar medium and flooed with gram's iodine. The isolates were screened quant. for the prodn. of α-amylase and glucoamylase using Solid state fermn. [SSF] while the enzyme activities were detd. spectrophotometrically. Results: Mean mold population obsd. on the spoilt food samples ranged from 5.06 log cfu/g for ogi to 5.80 log cfu/g for eko wrapped in leaves. Twenty seven molds isolated from the samples were identified as Aspergillus flavus, Aspergillus niger, Aspergillus fumigatus, Penicillium citrinum and Rhizopus stolonifer. Majority (70.4%) of the isolated mold produced amylase on starch agar indicated by clear zones around the colonies. Diam. of the zone of hydrolysis ranged from 3.0 mm for Aspergillus niger EL4 to 22.0 mm for Aspergillus flavus OG1. The highest amylase activity was 30.8% from A. flavus OGI while the least was 21.2% from A. flavus EN4. Glucoamylase activities obsd. were between 100 U/mL and 240 U/mL., resp. Conclusion: This study contributes to cataloged local fungal isolates that can be used for amylase prodn. and provides addnl. information to support future research about the industrial enzymes potential of these microorganisms. More work is however needed to det. the optimal prodn. conditions of the enzymes. [on SciFinder(R)]