Enhancement of biomass production and nutrition utilization by strain Lactobacillus acidophilus DGK derived from serial subculturing in an aerobic environment

Abstract

Successive subculturing under aerobic conditions for 14 days could be used to improve characteristics of a parent strain with a growth defect. Identification of the derived strain was based on the API 50 CHL test kit and partial sequencing of the hsp60 gene. Results show that an aerotolerant strain, Lactobacillus acidophilus DGK, was created with improved nutrition utilization. Characteristics of shorter rod-shape, higher growth rate and higher level of lactic acid concentration were observed in the domesticated strain which produced higher biomass (4.54 g dry cell weight (DCW)/L) and viable counts (9.5 x 10⁹ CFU/mL) compared to the original strain which were 1.06 g DCW/L and 1.61 x 10⁹ CFU/mL, respectively under aerobic conditions. Utilization of carbon and nitrogen sources was significantly improved by the derived strain except the raffinose. These results indicate that serial subculturing is a plausible method for the generation of modified strains with enhancing nutrition utilization or improving various characteristics which were beneficial in industrial processes.

Key words: Biomass; serial subculture; Lactobacillus acidophilus; hsp60 gene