Statistical optimisation of growth conditions and diesel degradation by the Antarctic bacterium, Rhodococcus sp. strain AQ5‒07

Abstract

Petroleum pollution is a major concern in Antarctica due to the persistent nature of its hydrocarbon components coupled with the region's extreme environmental conditions, which means that bioremediation approaches are largely inapplicable at present. The current study assessed the ability of the psychrotolerant phenol-degrader, Rhodococcus sp. strain AQ5-07, to assimilate diesel fuel as the sole carbon source. Factors expected to influence the efficiency of diesel degradation, including the initial hydrocarbon concentration, nitrogen source concentration and type, temperature, pH and salinity were studied. Strain AQ5-07 displayed optimal cell growth and biodegradation activity at 1% v/v initial diesel concentration, 1 g/L NH 4 Cl concentration, pH 7 and 1% NaCl during one-factor-at-a-time (OFAT) analyses. Strain AQ5-07 was psychrotolerant based on its optimum growth temperature being near 20 °C. In conventionally optimised media, strain AQ5-07 showed total petroleum hydrocarbons (TPH) mineralisation of 75.83%. However, the optimised condition for TPH mineralisation predicted through statistical response surface methodology (RSM) enhanced the reduction to 90.39% within a 2 days incubation. Our preliminary data support strain AQ5-07 being a potential candidate for real-field soil bioremediation by specifically adopting sludge-phase bioreactor system in chronically cold environments such as Antarctica. The study also confirmed the utility of RSM in medium optimisation.

Effects of heavy metals on diesel metabolism of psychrotolerant strains of Arthrobacter sp. from Antarctica

“…Thus, the presence of heavy metals in the soil environment creates a challenge for degrading diesel due to their highly toxic effects on petroleum-degrading bacteria. Furthermore, oil spills tend to persist longer in the Antarctic environment owing to the chronically low temperatures, limited nutrient availability and dry conditions, which slow down the rates of microbial processes and abiotic degradation (Aislabie et al, 2006;Ahmad et al, 2013;Roslee et al, 2020). Not with standing this, the use of microorganisms for remediating environmental pollutants such as petroleum hydrocarbons is receiving increasing attention as it causes less damage to the environment, is economically desirable and can completely remove harmful pollutants (Ahmad et al, 2013;Ibrahim et al, 2015;Nawawi et al, 2016;Al-Hadithi et al, 2017).…”

Biosurfactant Production and Growth Kinetics Studies of the Waste Canola Oil-Degrading Bacterium Rhodococcus erythropolis AQ5-07 from Antarctica

“…Antarctica is generally considered among the most pristine areas in the world. However, various areas in Antarctica have been contaminated with pollutants, including hydrocarbons [ 3 , 4 ]. Some Antarctic microorganisms produce biosurfactants, which increase biodegradation and the bioavailability of such contaminants.…”

“…Some Antarctic microorganisms produce biosurfactants, which increase biodegradation and the bioavailability of such contaminants. The application of bioremediation approaches in Antarctica, including oil-polluted soils, requires the use of indigenous microorganisms since, in accordance with Antarctic Treaty regulations, it is prohibited to introduce non-native biota [ 3 , 5 ].…”

“…In this study, Rhodococcus erythropolis strain AQ5-07, a soil bacterium previously isolated from King George Island (South Shetland Islands, maritime Antarctic; [ 18 ]), was tested for its ability to degrade canola oil and produce biosurfactants, and its growth kinetics were studied and modelled. Canola oil is mostly used in research stations and is use in various cooking techniques, besides it degradation, Rhodococcus erythropolis strain AQ5-07 also could degrade phenol and diesel in addition to heavy metals resistance [ 3 , 18 , 19 ].…”

Mini review on phenol biodegradation in Antarctica using native microorganisms

“…The terrestrial activities here are mainly referred to the occurrence of oil spill due to the transport of fuel to powerhouses as well as fuel spill while refilling fuel tanks and vehicles. The fuels usually used in Antarctica are gasoline, lubricant oil as well as diesel, which comprised high content of phenolic compounds (Roslee et al, 2019;Vázquez et al, 2017).…”