Enriching indigenous ureolytic bacteria in coastal beach sand

Abstract

In this study, a series of enrichment tests were conducted to investigate the effectiveness of two enriching media on the indigenous ureolytic bacteria in Hawaiian coastal beach sand. Sand collected from the intertidal zone of the Kailua Beach was used in the study, which was subjected to the erosion action of wave and tide periodically. Two media applied were YE (yeast extract only) and YEU medium (yeast extract with urea). Shaking incubation test was conducted up to 72 h to stimulate the indigenous ureolytic bacteria. The pH, ammonium concentration, ureolytic activity, and viable bacterial colony number of the enriched bacterial solution were measured at 6 h, 12 h, 24 h, 48 h and 72 h respectively. Results show that the primary stimulation occurred within the first 48 h. The concentration of ammonium ions and ureolytic activity were significantly increased and the viable bacterial colony number was slightly decreased at the end of the enrichment. These observations indicate that the ureolytic bacteria resided in the intertidal zone can be enriched effectively.