Philippine E-Journals

BIOREMEDIATION ACTIVITY OF ISOLATED CHROMIUM-RESISTANT BACTERIA FROM ESTUARY SEDIMENTS IN LA UNION, PHILIPPINES

DIVINE CLAIRE F. LORIDO | OLIVIENNE NOELLE P. GINES | ROSEMARY M. GUTIERREZ

Discipline: microbiology and cell science

 

Abstract:

Chromium contamination in sediments is contributed by industrialization. Elevated levels of Cr(VI) have crucial effects on living organisms' health and are detrimental to the environment. Bioremediation is an innovative and sustainable way of reducing hazardous substances to lesser ones. In this study, Cr-resistant bacteria were isolated from Maragayap Estuary sediments and its bioremediation activity was assessed. Soil samples were collected from the study site and were serially diluted and grown in Luria-Bertani (LB) medium. Soil microcosm was amended with 60 ppm Cr(VI) and its heavy metal levels were evaluated in four weeks through US EPA 3060A and 7196A. Bacterial isolates were characterized and identified by 16s rRNA gene sequencing and their phylogenetic trees were constructed. Based on heavy metal analyses, Maragayap Estuary was found to be polluted with chromium. Isolates, designated as LG-01 and LG-03, were identified as Staphylococcus sciuri and Bacillus cereus, and LG-02 as the novel bacteria, Bacillus aerius. It was observed that all isolates can tolerate up to 300 ppm of chromium. The two Bacillus species produced putative carotenoids due to heavy metal stress. Results revealed that there was a reduction of Cr(VI), as bioremediation time progresses. The bacterial consortium reduced chromium faster than pure cultures at a rate of 0.8931 ppm/week. Individually, S. sciuri had the highest reduction of 1.65 ppm in four weeks. The results of this study may inform the community on possible human pathogens thriving in estuaries and may provide a possible microbial source of bioremediation agent to address environmental concerns in the freshwater ecosystem.