Modares Journal of Biotechnology

Abstract  As a starch hydrolyzing enzyme, α-amylase is important in the food industry and ethanol and biofuel production. This research aims to investigate the production of α-amylase enzyme in microorganisms from different regions of Iran and microbial collection centers of Iran. The results showed that 183 out of 331 isolates screened had α-amylase activity. Of these, two strains isolated from agricultural soil, named AGR228 and AGR91, had the maximum halo-to-colony ratio. In addition, all the strains belonging to the microbial collection centers showed amylase activity, of which PTCC-1732 and PTCC-1156 showed the highest activity. The amount of amylase produced in PTCC-1732 and AGR228 was estimated to be 20.5 and 11.18 units/ml, respectively. The maximum activity of the amylase enzyme from PTCC-1732 is at 80°C, and  pH 10. In the case of AGR228, the maximum activity was measured at 60°C, and  pH 8.
 

Abstract The aim of this study was to isolate and identify a-amylase-producing bacteria present in mangrove ecosystems on Qeshm Island, Hormozgan, Iran. Samples of mangrove leaves and roots were screened for a-amylase activity using Lugol’s solution. Crude extracts were prepared of positive samples, and their a-amylase activity was determined by the Bernfeld method. The two strains with the highest activity were identified by molecular analysis of their 16S rRNA genes. a-Amylase production and activity were optimized by varying temperature and pH. 46 bacterial strains were isolated from mangrove tree leaf and root samples. Of these, 28 strains were capable of producing a-amylase. 16S rRNA gene sequence analysis of two strains with the highest enzyme production identified them as Bacillus sp. strain HR10 and Bacillus sp. strain HR11. The optimum temperature for enzyme production was 35 and 30 °C for strains HR10 and HR11, respectively, and the optimum pH was pH 8 for both strains. The highest enzyme activity was observed at 70 °C and 60 °C for the HR10 and HR11 strains, respectively, and the optimum pH was pH 8 for both strains. In conclusion, we have shown that bacteria isolated from mangrove leaf and root samples are potential source of a-amylases, tolerating a wide range of temperature and pH. Such a-amylases may be of interest for use in environmentally friendly industries.

Abstract Aims: Significant amounts of waste, including feathers, bones, blood, etc. are yearly produced by the poultry industry. Feathers are composed of 90% keratin protein, and the rest is composed of lipids and water. Keratinases are one of the most diverse and usable enzymes, which can be produced by bacterial and fungal microorganisms. These enzymes show a wide range of application in various fields.
Materials and Methods: In this study, the keratinolytic activity of the isolated strain from a poultry farm in Mashhad was evaluated and then the medium conditions for keratinase production were optimized. The strains were identified based on the morphological and biochemical methods. 16SrRNA gene of the strain was amplified by PCR and then sequenced. The strain proteolytic activity was examined and compared with its keratinolytic activity. Finally, strain growth ability tested in variety substrate.
Findings: Using 16SrRNA gene sequencing, morphological and biochemical identification, the strain shared 99.9% similarity with Bacillus mojavensis. Optimization of various factors, including temperature, pH, incubation time, carbon and nitrogen sources, aeration and inoculum size showed that the isolated strain has the highest keratinolytic activity at 37°C, 48 hour incubation period, pH=9.5, sucrose 1%, 3% substrate, aeration 75% and 6% (v/v) inoculum amount. None of the nitrogen sources had a positive effect.
Conclusion: The FUM-1 keratinolytic activity was increased approximately 3.38 fold by condition optimization of the medium, indicating the importance of environmental conditions. In the study, the strain with high keratinolytic activity was suggesting its potential use in biotechnological.

Abstract Production and characterization of bacterial thermophilic avicelase Fatemeh Azadian, Arastoo Badoei-dalfard*, Abdolhamid Namaki-Shoushtari, Mehdi Hassanshahian Department of Biology, Faculty of Sciences, Shahid Bahonar University of Kerman, Kerman, Iran Nowadays, developing processes for effectively converting agricultural wastes for production of high value chemicals has gained considerable interest. Avicelases are important industrial enzymes for the most bioconversion processes. In this study, samples were picked up and inoculated in AVI broth for 7 days at 50 ºC. The bacterial strains with the clear halo (represent extracellular avicelase) have been purified. AV8 isolate which showed the highest clear halo was selected for further studies. This strain was identified as Bacillus genus based on biochemical tests and 16S rRNA analysis. Avicelase production was considered under varying environmental parameters. The best carbon and nitrogen sources for maximum avicelase production were 0.5% sucrose and 0.25% yeast extract, respectively. Avicelase from this strain has been partially purified using ammonium sulphate fractionation followed by dialysis and ion exchange Q-Sepharose chromatography. Results showed that enzyme was active and stable between 30-70 ºC and itʼs maximum temperature activity was observed in 70 ºC. The optimum avicelase activity and stability was observed at pH 6.0. These are characteristics indicating that this enzyme could be an acidophilic and thermophilic avicelase. Furthermore, the avicelase activity improved by methanol (138 %) and chloroform (107 %). These results indicated that AV8 avicelase has potential applications in various industries.