title: Development of a solid-state fermentation process for production of an alpha amylase with potentially interesting properties.
abstract: Ca-independency with potential activity and stability at low pH are among the most interesting characteristics of alpha-amylase in starch industry. In this attempt the synergetic effect of low pH on activity of crude Ca-independent alpha-amylase isolated from a native Bacillus sp. KR-8104 in solid-state fermentation (SSF) was studied using wheat bran (WB) as a substrate. The effects of different parameters including moisturizing agents, solid substrate to moisture ratio, particle size, incubation temperature and period, inoculum (v/w) and supplementation with 1% (w/w) different carbon and nitrogen sources on enzyme production were investigated. Maximum enzyme production of 140U/g dry fermented substrate was obtained from wheat bran moistened with tap water at a ratio of 1:1.5 and supplemented with 1% (w/w) NH(4)NO(3) and 1% (w/w) lactose after 48h incubation at 37 degrees C. Even though the production of alpha-amylase was lower at 40 and 45 degrees C, the viable cell count was higher. In addition response surface methodology (RSM) was applied to find optimum conditions of temperature and pH on crude amylase activity. Using central composite design (CCD) a quadratic mathematical model equation was derived for the prediction of enzyme activity. The results showed that the model was in good agreement with experimental results, with R(2)=0.90 (p<0.0001) and the low pH has a synergetic effect on enzyme activity at higher temperature.
authors.affiliation: Department of Food Science and Engineering, Faculty of Engineering and Technology of Agriculture, University of Tehran, Karaj, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Hashemi
authors.forename: Seyed Hadi
authors.initials: SH
authors.lastname: Razavi
authors.forename: Seyed Abbas
authors.initials: SA
authors.lastname: Shojaosadati
authors.forename: Seyyed Mohammad
authors.initials: SM
authors.lastname: Mousavi
authors.forename: Khosro
authors.initials: K
authors.lastname: Khajeh
authors.forename: Mohammad
authors.initials: M
authors.lastname: Safari
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D019149:Bioreactors / Q000382:microbiology*; D004789:Enzyme Activation; D004795:Enzyme Stability; D005240:Feasibility Studies; D005285:Fermentation / Q000502:physiology; D010936:Plant Extracts / Q000737:chemistry*; D012639:Seeds / Q000382:microbiology*; D014908:Triticum / Q000382:microbiology*; D000516:alpha-Amylases / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D010936:Plant Extracts; D000516:alpha-Amylases