Deciphering Cadmium (Cd) Tolerance in Newly Isolated Bacterial Strain, Ochrobactrum intermedium BB12, and Its Role in Alleviation of Cd Stress in Spinach Plant (Spinacia oleracea L.)

Abstract

A cadmium (Cd)–tolerant bacterium Ochrobactrum intermedium BB12 was isolated from sewage waste collected from the municipal sewage dumping site of Bhopal, India. The bacterium showed multiple heavy metal tolerance ability and had the highest minimum inhibitory concentration of 150 mg L–1 of Cd. Growth kinetics, biosorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy studies on BB12 in the presence of Cd suggested biosorption as primary mode of interaction. SEM and TEM studies revealed surface deposition of Cd. FTIR spectra indicated nitrogen atom in exopolysaccharides secreted by BB12 to be the main site for Cd attachment. The potential of BB12 to alleviate the impact of Cd toxicity in spinach plants (Spinacia oleracea L.) var. F1-MULAYAM grown in the soil containing Cd at 25, 50, and 75 mg kg–1 was evaluated. Without bacterial inoculation, plants showed delayed germination, decrease in the chlorophyll content, and stunted growth at 50 and 75 mg kg–1 Cd content. Bacterial inoculation, however, resulted in the early germination, increased chlorophyll, and increase in shoot (28.33%) and root fresh weight (72.60%) at 50 mg kg–1 of Cd concentration after 75 days of sowing. Due to bacterial inoculation, elevated proline accumulation and lowered down superoxide dismutase (SOD) enzyme activity was observed in the Cd-stressed plants. The isolate BB12 was capable of alleviating Cd from the soil by biosorption as evident from significant reduction in the uptake/translocation and bioaccumulation of Cd in bacteria itself and in the plant parts of treated spinach. Potential PGP prospects and heavy metal bioremediation capability of BB12 can make the environmental application of the organism a promising approach to reduce Cd toxicity in the crops grown in metal-contaminated soils.

Bioremediation potential of Brevibacillus parabrevis AMB‐CD‐2 in spinach under lead toxicity

“…Parallelly, the work done by Renu et al (2021) concluded that heavy metal tolerant bacterial strains like MB1, RD4, MF7, and MC4 promoted the growth of spinach plants in terms of root and shoot length, fresh and dry root weight, and shoot weight in the presence of heavy metals like arsenic, chromium, nickel, and lead and also reduced the heavy metal toxicity in spinach. Also, the findings of Renu et al (2022) concluded that inoculation of Cd‐tolerant bacterium Ochrobactrum intermedium BB12 in spinach plants under Cd stress conditions, showed increased germination, increased chlorophyll content, and increased shoot (28.33%) and root fresh weight (72.60%) at 50 mg/kg of cadmium concentration after 75 days of sowing.…”

Bacterial Communities Associated with the Roots of Typha spp. and Its Relationship in Phytoremediation Processes

“…Shehzadi et al [106] isolated cultivable endophytic bacteria from the shoots and roots It is known that the versatile Pseudomonas genus can tolerate HMs because of its ability to adapt to various environmental conditions [108,109]. Ochrobactrum strains have been shown to alleviate Cd toxicity in spinach (Spinacia oleracea L.) [110] and rice (Oryza sativa) [111] and adsorb Cd and Cr in their cell wall due to exopolysaccharides content [112][113][114]. Similarly, some Acinetobacter strains have been applied to improve the removal efficiency of heavy metals such as Cr [115][116][117], while Alcaligenes has been reported to be tolerant to Cd, Cu, Ni, Zn, and Cr [118,119].…”

Evaluation of the oxidative stress alleviation in Lupinus albus var. orden Dorado by the inoculation of four plant growth-promoting bacteria and their mixtures in mercury-polluted soils

“…Similarly, Pirzadah et al (2018) investigate the effect of Hg on oxidative stress in plants not inoculated with PGPB, finding similar results to those described in the present work. The effect that PGPB inoculation induces the decrease of ROS is known (Heidari and Golpayegani, 2012;Morcillo and Manzanera, 2021) in substrates contaminated by different heavy metals: Hg (Pirzadah et al, 2018), Pb (Abdelkrim et al, 2018), Cu (Fatnassi et al, 2015), Zn (Islam et al, 2014), and Cd (Azimychetabi et al, 2021;Renu et al, 2022). The PGPB species commonly used are those belonging to the genus Bacillus (Vardharajula et al, 2011;Moreno-Galván et al, 2020) and Pseudomonas (Sandhya et al, 2010).…”