Monitoring of heavy metals level in fish using Photobacterium sp. strain MIE

Abstract

Luminescence-based assays for toxicants such as Microtox®, ToxAlert™ and Biotox™ have been used extensively worldwide. However, the use of these assays in near real-time conditions is limited due to nonoptimal assay temperature for the tropical climate. An aerobic isolate that exhibits a high luminescence activity in a broad range of temperatures was successfully isolated from the mackerel, Rastrelliger kanagurta. This isolate was tentatively identified as Photobacterium sp. strain MIE, based on partial 16S rDNA molecular phylogeny. Optimum conditions that support high bioluminescence activity occurred between 24 and 30 oC, pH 5.5 and 7.5, 10 and 20 g/L of sodium chloride, 30 and 50 g/L of tryptone, and 4 g/L of glycerol as the carbon source. Assessment of near real-time capability of this bacterium for heavy metals in a contaminated river running through the Juru River Basin that fed a large agriculture area has shown near real-time capability with assaying time of less than 30 min per samples. Thus, this strain is suitable for near real-time monitoring of toxicants especially in the tropics