Biodegradation of formaldehyde gas pollutant by a novel immobilized haloalkaliphilic Salipaludibacillus agaradhaerens strain NRC-R isolated from hypersaline soda lakes

Abstract

Indoor formaldehyde (HCHO) exceeding the recommended level, is harmful to human health. The goal of this study was to test the performance of a novel haloalkaliphilic (HAP) Salipaludibacillus agaradhaerens strain NRC-R isolated from hypersaline soda lakes and immobilized in alginate-PVA-chitosan gel composite to biodegrade HCHO gas in a stream of air containing various inlet HCHO concentrations (0.7 ppm and 7 ppm) in laboratory scale. The surface images of the immobilized cells/beads were examined by scanning electron microscopy (SEM). The maximum efficiency of HCHO removal was almost 90% with an inlet loading concentration of 0.7 ppm. Stepwise 10 times augment in the HCHO inlet concentration (7 ppm) showed that the immobilized strain was able to control this very high concentration and removed about 60% over 72 h of the treatment. Although several studies have been reported on the isolation of HAP bacteria from various environments, but to our knowledge, this is the first report on the isolation and immobilization of highly HCHO-controlled HAP bacterial strain from soda lakes of hypersaline in Egypt. This bio-system has a high biodegradation capacity via HCHO gas pollutant even with the higher concentrations (7 ppm). It is assumed that HAP S. agaradhaerens NRC-R strain could be utilized in the remediation and biodegradation of HCHO air pollutants. Furthermore, this novel strategy may be considered in employing such bacteria as a biotechnological treatment technique that reduces the environmental pollution rate and might be useful to control other organic compound pollutants in many industrial fields.