Seleção e isolamento de bactérias resistentes a Cromo Hexavalente Endêmicos do Igarapé do Quarenta

Abstract

The accelerated expansion of the urban center of the city of Manaus has generated important impacts on the water resources of the region. In the middle of this scenario, the present work aims to isolate samples from the bacterial communities associated to the water of the Quarenta stream, evaluating their bioreduction potentials for hexavalent chromium. The methodology used includes the collection of water samples at strategic points along the Forty stream, evaluation of the isolates in culture medium with chromium (VI) concentrations varying from 0.01 mg / L to 320 mg / L, selecting from this the best strains and identifying them by molecular sequencing technique. After the selection of the isolate, the growth of the isolate at the concentration of 300 mg / L was evaluated over 72 hours compared to the control in medium without the metal. At the same time, a simulated environment with a concentration of 10 mg / L Cr (VI) was monitored with pH monitoring every 12 hours until the final time of 72 hours. Twenty-three strains resistant to the concentration of 300 mg / L of chromium (VI) were obtained, where 18 strains were selected to reduce Cr (VI) and later identified by sequencing the 16S region. Ten bacterial genera were identified, among them the genera Acidovorax sp., Acinetobacter sp., Alicycliphilus sp., Bacillus sp., Comamonas sp., Enterobacter sp., Micrococcus sp., Proteus sp., Serratia sp. and Vagococcus sp. The bacterium of the genus Vagococcus sp. reduced 96.8% Cr (VI) to 10 mg / L in only 24 hours. The growth of this strain at the concentration of 300 mg / L, despite being delayed by the amount of metal present, after 48 hours was equal to the control, showing that this genus has potential for remediation of environments impacted by metals.