Isolation and Characterization of Copper Tolerant Bacterial Species Habituating in Copper Mines and Study of Their Potentiality as a Plant Growth Stimulator

Abstract

Copper (Cu) is a vital micronutrient for all living organisms below its toxicity limit. Various industrial activities, mining deposits, excessive use of harmful chemicals, waste discharges, and drugs are the main reason for the emerging copper concentration. Emphases of the current study were to isolate and characterize highly copper-tolerating bacterial (CTB) species from a copper-contaminated site. In enrichment culture techniques, 24 copper tolerant microbial isolates were evaluated and the maximum tolerable concentration (MTC) was determined using various concentrations of copper sulfate pentahydrate (CuSO4.5H2O) solution. Three bacterial strains named GKSM2, GKSM6, and GKSM11 were tolerant to 350 mg/l of CuSO4.5H2O. The 16S rRNA gene sequencing and phylogeny data revealed that these CTB belong to species Bacillus zanthoxyli, Bacillus stercoris, and Pseudomonas alcaliphila species. CTB showed their optimized growth at moderate salt concentration (0.1-0.5M NaCl), temperature range (20-45˚C) and wide pH range (pH 5.0-11). All the strains can produce various Plant growth stimulating (PGS) traits viz., phytohormones (IAA, GA), proline, nitrogen fixation, ammonification, and antioxidant enzymes in presence and absence of Cu2+ stress. The result displays that adsorption of Cu2+ ions evidenced by TEM, SEM, and SEM-EDX analysis.

Heavy‐metal tolerant bacterial strains isolated from industrial sites and scrap yards in Kashmir, India

“…Out of 20 heavy metal‐resistant bacterial isolates, only 04 isolates were further studied based on their ability to resist high concentrations of FeSO 4 .7H 2 O and CuSO 4 .5H 2 O. The growth capacities of iron and copper tolerant isolates at different temperatures (4°C, 25°C, 37°C, and 45°C) and varying pH (2.0, 4.0, 7.0, 8.0, and 10.0) values were demonstrated in our result, showing that the maximum growth of isolates was found at 37°C and pH 7 after incubation of 24 h. This is consistent with the result of earlier studies where the growth was observed at 37°C and pH 7 [56]. Among all heavy metal‐tolerant bacterial strains, Pantoea sp.…”

“…The bacterial strains SC5, SC8, and SC10 showed high tolerance to Fe (FeSO 4 .7H 2 O) upto 700 μg/mL, followed by bacterial strains GN2 with heavy metal tolerance upto the other hand, some findings demonstrated that P. agglomerans were tolerant to Cu, having a MIC value of 7 mM [55]. Out of 20 heavy metal-resistant bacterial isolates, only 04 isolates were further studied based on their ability to resist high concentrations of FeSO showing that the maximum growth of isolates was found at 37°C and pH 7 after incubation of 24 h. This is consistent with the result of earlier studies where the growth was observed at 37°C and pH 7 [56]. Among all heavy metal-tolerant bacterial strains, Pantoea sp.…”