Utilization of Agro-industrial Residues for Production of Amino Acids Using Egyptian Bacillus spp. Strains

Abstract

Two amino acids producing strains of Bacillus (R22EG1 and R20EG2) were isolated from soil rhizosphere in Kalubia Governorate, Egypt. Identification of the isolates were carried out using phenotypic characteristics, phylogenetic positions based on 16S rRNA gene sequence analysis and base sequences (submitted to NCBI GenBank). 16S rRNA gene sequence analysis confirmed that these isolates belonged to the genus Bacillus. Strain Bacillus sp. R22EG1 was most closely related to Bacillus sp. B1, Bacillus sp. B3and Bacillus sp. D2.Strain Bacillus sp. R20EG2 was most closely related to Bacillus sp. CRRI-49, B. cereus strain 08001,B. cereus strain TCCC11307, B. cereus strain JY13, B. anthracis strain APT10 and Bacillus sp. 6042 (92 % similarity). For the production of amino acids, some agro-industrial residues were added as carbon and nitrogen sources to the medium. The strains gave the maximum concentration of amino acids on the modified molasses medium as a low price productive medium composed of sugarcane molasses (50 ml.l-1) as carbon source and soybean husk (20 g.l-1) as nitrogen source and a mixture of mineral elements after 72 h at 30°C using shake flasks as a batch culture. Concentrations of amino acids were; 2.28 g.l-1 (R2=0.873) and 2.49 g.l-1 (R2=0.737) for Bacillus sp. R22EG1 and Bacillus sp. R20EG2, respectively. The specific growth rates (μ) were; 0.0851 h-1& 0.0776 h-1. The corresponding figures for doubling times (td) were; 8.14 h & 8.93 h for Bacillus sp. R22EG1 and Bacillus sp. R20EG2, respectively.