Endophytic Bacteria Tolerant To High Cadmium Concentrations

Abstract

To assess the in vitro capacity of endophytic bacteria tolerance isolated from different tissues of the rice variety Fedearroz 2000 (F2000), to different concentrations of cadmium in the form of CdCl₂. The bacteria were isolated from root, stem, leaf and panicle F2000. Suspensions each log phase was inoculated into minimal medium tris-MMT with different concentrations of CdCl₂. The experiment was incubated with stirring at 150 rpm at 32 °C for seven days; growth isolated in the assay was determined by turbidimetry at 600 nm every hour for four days. Siderophore production was determined by the growth of bacteria in mediumazurol-S (CAS). There is an inverse relationship between number of bacteria and tissue concentration of cadmium, being more bacteria in those tissues where there is lower concentration of cadmium. isolates were identified as Bacillus thuringiensis H1M3F2000LIM F14 and P1M8 F2000LIM Bacillus cereus LB10, able to tolerate up to 400 ppm of and 500 CdCl₂, respectively. In the middle CAS, H1M3F2000LIM evidenced siderophore production. The information obtained in this study suggests future use of endophytic bacteriaone biological strategy to recover agricultural soils contaminated with cadmium.