Isolation and screening of arsenic resistant rhizobacteria of Ludwigia octovalvis

Abstract

Ludwigia octovalvis was characterized for its potential in arsenic phytoremediation. Epiphyte rhizobacteria from the roots of L. octovalvis were isolated in five different arsenic concentrations (4, 20, 40, 60 and 80 mg kg^-1) and control after single exposure for 35 days. Results show that 109 colonies were isolated which were further grouped into 29 groups of isolated rhizobacteria. After preliminary screening, 17 rhizobacterial isolates were considered to be resistant to arsenic (arsenate or As[V]) and after secondary screening, 12 rhizobacterial isolates showed potential resistance to arsenic. Identification was conducted using biolog GEN III microbial identification system. One of the arsenate potentially resistant rhizobacterial was identified as Arthrobacter globiformis. The k (growth rate constant) value of A. globiformis was 0.112 h^-1 with g (generation time) value of 8.943 h and ì (specific growth rate) value of 0.077 h^-1. Minimal inhibitory concentration (MIC) value of A. globiformis on arsenate exposure was 500 mg L^-1 and has the potential to promote arsenic phytoremediation at contaminated site.

Key words: Phytoremediation, arsenic, isolation, screening, identification, minimal inhibitory concentration (MIC).