Ochrobactrum pseudintermedium

Abstract: Chromium (VI) is one of the toxic heavy metals causing various human ailments like asthma to severe forms of cancer; hence, its removal from industrial effluents is essential. The present study demonstrates ameliorating techniques for the removal of Cr(VI). A chromium-reducing bacterium (CRB) identified as Ochrobactrum pseudintermedium ADV31 through 16S rRNA gene sequencing, was found to remove concentrations of Cr(VI) up to 600 mg/L in nutrient medium. Calcium alginate (CA) and polyurethane foam (PUF) were the two different materials used for the immobilization of Ochrobactrum pseudintermedium ADV31. The efficiency of the immobilized cells and free form of bacterial cells with inoculum concentrations of 1% and 5% were compared for the removal of Cr(VI). Calcium alginate with 5% inoculum concentrations showed removal of 82% of 600 mg/L in 5 days, while PUF with 5% inoculum size showed removal up to 86% of 600 mg/L in 5 days. Free form of bacterial cell was able to remove 36.7%. The bacterium was able to tolerate a wide range of pH ranging from 6 to 9 and had an optimum temperature of 45 °C. The results confirmed that both forms of immobilization methods are equally effective for the removal of hexavalent chromium and can be used for various biotechnological processes for the metal bioremediation.

Abstract: A new strain of bacterium Ochrobactrum pseudintermedium KF026284 was isolated from a single chambered microbial fuel cell operated with rumen fluid. The bacterium produced maximum power density of 114 mW/m2 (0.7 V, 0.6 mA) when nutrient broth was used as the growth medium. The optimization of electricity generation by O. pseudintermedium KF026284 was carried out using various substrates like cellulose, cellobiose, starch, sucrose, and glucose. The bacterium when fed with cellobiose showed an appreciable and sustainable electricity generation with a power density of 150 mW/m2 from the 5th day and a maximum power density of 247 mW/m2 on the 11th day.

Abstract: Endophytic bacteria (EB) isolated from healthy cucumber plant tissues (e.g., root, stem, leaves) were evaluated as possible biological control of Pseudomonas syringae pv. lachrymans, the causative agent of angular leaf spot disease in cucumber. In this study, 24 endophytic bacteria were selected for tests based on biocontrol traits such as indole-3-acetic acid and siderophore production, solubilization of phosphate, and inhibition growth of P. syringae pv. lachrymans in vitro. Some of the selected endophytes successfully inhibited the pathogen were tested in pots. In the pot experiment, two isolates (CB361-80) and (CC372-83) were selected as the most promising biocontrol agents tested against the pathogen. According to the identification carried out by using 16S rRNA primers and sequence analysis, the two selected endophyte isolates (CB361-80) and (CC372-83) showed 99% similarity to Ochrobactrum pseudintermedium and Pantoea agglomerans, respectively. Two EB isolates colonized seeds at the rate of 3 × 106–7.1 × 107 CFU/g 1 day after seed bacterization. The population of the two EB isolates in cucumber tissues were found to be about 2 × 104–7.5 × 104 CFU/g in roots and 3.8 × 104–2.2 × 105 CFU/g in shoots 45 days after seed bacterization. The populations of the two isolates in the root and shoot tissues did not decrease following the inoculation of the pathogenic bacterium. The endophytic strains CB361-80 (Ochrobactrum sp.) and CC372-83 (Pantoea sp.) successfully colonized the cucumber tissues.