Characterization of an Acrylamide-degrading Bacterium Isolated from Hydrocarbon Sludge

Abstract

A major source of acrylamide in soil comes from herbicide formulation that contained polyacrylamide that slowly decomposes to acrylamide. Research in acrylamide biodegradation by microbe as a tool for its bioremediation is slowly gaining attention globally. In this research, a hydrocarbon-degrading Pseudomonas sp. strain Dr Y Kertih isolated from petroleum sludge was able to grow on acrylamide. The results show that 1% (w/v) glucose supplied with acrylamide (as the only nitrogen source) was the best carbon source for the growth of acrylamide-degrading bacterium. The isolate was also able to use diesel as a carbon source. The bacterium shows an optimal growth at 300 mg/L acrylamide, pH between pH 6.5 and 7.5 and temperature between 25 and 30 °C. The isolate was able to grow on amides such as acetamide and 2-chloroacetamide, but their growth was inhibited by toxic heavy metals such as mercury, cadmium and chromium. Growth kinetic studies using the Haldane model for growth indicated substrate toxicity at higher concentrations on acrylamide. The maximum growth rate (µmax) was 0.267 h-1 while the saturation constant or half velocity constant Ks and inhibition constant Ki, were 0.182 and 0.25 g/L, respectively. Thus, the bacterium holds great potential as a candidate to remediate acrylamide.

Characterization of An Acrylamide-degrading Bacterium Isolated from Volcanic Soil

“…The results of this study show that the bacterium responsible for the degradation of acrylamide was able to make use of basic aliphatic amides, as was previously documented by other research [28,[41][42][43][44][45][46][47]. It is also unable of degrading 2chloroacetamide, an amide molecule that many degraders are unable to use.…”

Characterization of the Growth of Pseudomonas sp. strain DrY135 on Acrylamide

“…Research examining the impact of pH on acrylamide development has yielded consistent results, as seen in the present study. Many microbes that break down acrylamide prefer an environment with a pH of about 7.0 [14][15][16][17][18][19][20][21][22][23]. Soils in tropical regions often have a lower pH because of the high levels of metabolic activity that produce organic acid and carbon dioxide.…”

“…A key factor in how quickly acrylamide is broken down by bacteria is temperature. Researchers have found that several bacteria capable of digesting acrylamide thrive at temperatures close to 30 degrees Celsius [14][15][16][17][18][19][20][21][22][23]. However, thermoactive bacteria, including Pseudonocardia thermophilic and Brevibacillus borstelensis BCS-1, require higher temperatures for optimum growth, with 50(C and 55(C being required, respectively [29,30].…”

“…Based on previous works, heavy metals have a significant impact on the breakdown of acrylamide, with greater inhibition occurring in the presence of mercury, copper and silver than other metals [15][16][17][18][20][21][22][23].In the published study that is available at this time, there is a dearth of knowledge concerning the effect that heavy metals have on the degradation of acrylamide and even other xenobiotics. This lack of information is due to the fact that the research has not yet been sufficiently conducted.…”

“…Although acrylamide is quickly metabolized and eliminated from the body after exposure, it nevertheless poses a concern to workers and consumers [11][12][13] due to its high protein reactivity. Bacteria are still the most common type of microorganism shown to break down acrylamide [14][15][16][17][18][19][20][21][22][23]. Here we describe the isolation and characterization of another Pseudomonas acrylamide-degrading strain with metal-reducing capability.…”