Immobilization of the surfactant-degrading bacterium Pseudomonas C12B in polyacrylamide gel beads: I. Effect of immobilization on the primary and ultimate biodegradation of SDS, and redistribution of bacteria within beads during use

Alcohol ethoxylate degradation of activated sludge is enhanced by bioaugmentation with Pseudomonas sp. LZ-B

An effective bioaugmentation strategy was developed for the removal of alcohol ethoxylates (AEs) from municipal wastewater. An AE-degrading strain, Pseudomonas sp. LZ-B, was isolated from an activated sludge. Strain LZ-B was able to degrade 96.8% of 200 mg/L C₁₂E₄ (Brij 30) within 24 h and showed significant biomass increase and removal of total oxygen concentration (TOC). The optimal degradation temperature and pH value were 37 °C and 6.0, respectively. The strain demonstrated greater potential to degrade five different molecular weight AEs within 5 days. HPLC-MS/MS analysis demonstrated that the major metabolites obtained were polyethylene glycol (PEG) and carboxylated AE chains. Activated sludge has a low ability to remove AEs. After inoculation of strain LZ-B into the activated sludge reactor, Strain LZ-B successfully colonized the activated sludge, and AE removal efficiency increased to more than 95% when the hydraulic retention time (HRT) was 10 h. After strain LZ-B cleaved the AE chains, the sludge microbial communities easily removed PEG fragments to facilitate complete biodegradation of AEs. This is the first report describing bioaugmentation to increase AE degradation in an activated sludge system.

Immobilization of Microbes for Bioremediation of Crude Oil Polluted Environments: A Mini Review

Petroleum hydrocarbons are the most common environmental pollutants in the world and oil spills pose a great hazard to terrestrial and marine ecosystems. Oil pollution may arise either accidentally or operationally whenever oil is produced, transported, stored and processed or used at sea or on land. Oil spills are a major menace to the environment as they severely damage the surrounding ecosystems. To improve the survival and retention of the bioremediation agents in the contaminated sites, bacterial cells must be immobilized. Immobilized cells are widely tested for a variety of applications. There are many types of support and immobilization techniques that can be selected based on the sort of application. In this review article, we have discussed the potential of immobilized microbial cells to degrade petroleum hydrocarbons. In some studies, enhanced degradation with immobilized cells as compared to free living bacterial cells for the treatment of oil contaminated areas have been shown. It was demonstrated that immobilized cell to be effective and is better, faster, and can be occurred for a longer period.

Microbial alkyl- and aryl-sulfatases: mechanism, occurrence, screening and stereoselectivities

This review gives an overview on the occurrence of sulfatases in Prokaryota, Eukaryota and Archaea. The mechanism of enzymes acting with retention or inversion of configuration during sulfate ester hydrolysis is discussed taking two complementary examples. Methods for the discovery of novel alkyl sulfatases are described by way of sequence-based search and enzyme induction. A comprehensive list of organisms with their respective substrate scope regarding prim- and sec-alkyl sulfate esters allows to assess the capabilities and limitations of various biocatalysts employed as whole cell systems or as purified enzymes with respect to their activities and enantioselectivities. Methods for immobilization and selectivity enhancement by addition of metal ions or organic (co)solvents are summarised.

Bioremediation of crystal violet using air bubble bioreactor packed with Pseudomonas aeruginosa

Seven water and sediment samples were collected and tested for decolorizing crystal violet. Pseudomonas aeruginosa was the most effective isolate for dye decolorization. The LC50 of the crystal violet (115 mg/l) was measured using Artemia salina as a biomarker. The effect of different heavy metals on crystal violet decolorization was investigated. Cd2+ and Fe3+ ions showed marginal enhancement of the decolorization process, the rate was 1.35 mg/l/h compared to (1.25 mg/l/h) for the control. Phenol and m-cresol showed no effect on crystal violet decolorization, meanwhile p-cresol and p-nitrophenol reduced the decolorization rate to 1.07 and 0.01 mg/l/h, respectively. P. aeruginosa cells were immobilized by entrapment in agar-alginate beads. The beads were cultivated and reused in Erlenmeyer flask and in an air bubble column bioreactor and they enhanced the crystal violet decolorization rate to 3.33 and 7.5 mg/l/h, respectively.

Bioremediation of crystal violet using air bubble bioreactor packed with Pseudomonas aeruginosa

Seven water and sediment samples were collected and tested for decolorizing crystal violet. Pseudomonas aeruginosa was the most effective isolate for dye decolorization. The LC(50) of the crystal violet (115 mg/l) was measured using Artemia salina as a biomarker. The effect of different heavy metals on crystal violet decolorization was investigated. Cd(2+) and Fe(3+) ions showed marginal enhancement of the decolorization process, the rate was 1.35 mg/l/h compared to 1.25 mg/l/h for the control. Phenol and m-cresol showed no effect on crystal violet decolorization, meanwhile p-cresol and p-nitrophenol reduced the decolorization rate to 1.07 and 0.01 mg/l/h, respectively. P. aeruginosa cells were immobilized by entrapment in agar-alginate beads. The beads were cultivated and reused in Erlenmeyer flask and in an air bubble column bioreactor and they enhanced the crystal violet decolorization rate to 3.33 and 7.5 mg/l/h, respectively.

Biological activity and environmental impact of anionic surfactants

The newest results concerning the biological activity and environmental fate of anionic surfactants are collected and critically evaluated. The chemical and physicochemical parameters related to the biological activity and the field of application are briefly discussed. Examples on the effect of anionic surfactants on the cell membranes, on the activity of enzymes, on the binding to various proteins and to other cell components and on their human toxicity are presented and the possible mode of action is elucidated. The sources of environmental pollution caused by anionic surfactants are listed and the methods developed for their removal from liquid, semiliquid and solid matrices are collected. Both the beneficial and adversary effects of anionic surfactants on the environment are reported and critically discussed. It was concluded that the role of anionic surfactants in the environment is ambiguous: they can cause serous environmental pollution with toxic effect on living organisms; otherwise, they can promote the decomposition and/or removal of other inorganic and organic pollutants from the environment. The relationship between their chemical structure, physicochemical parameters, biological activity and environmental impact is notwell understood. A considerable number of data are needed for the development of new anionic surfactants and for the successful application of the existing ones to reduce the adversary and to promote beneficial effects.