DETERMINATION OF DEGRADATION ABILITY AND KINETIC ABILITY OF HYDROCARBONOCLASTIC BACTERIA FROM PETROLEUM CONTAMINATED ENVIRONMENT

1.0 INTRODUCTION Globally, environmental pollution associated with the use of petroleum hydrocarbons (saturates, aromatics, resins, asphaltenes, etc.) and their products is an alarming issue (Xu et al., 2018, Lednev et al., 2021). The release of crude petroleum oil into the atmosphere is a major contributor to environmental degradation and pollution. Crude oil is highly hydrophobic and has a low polarity, which causes it to stick to soil particles. Crude oil can seep into the soil to a depth of more than 10 to 30 cm, which ultimately causes the soil's qualities to deteriorate and affects the plants in the affected areas (Adams et al., 2015). Specific components of crude oil, such as polyaromatic hydrocarbons (PAHs), are known to have mutagenic, teratogenic, carcinogenic, and even immunosuppressive properties (Bekhit et al., 2020). By food chain transfer of such recalcitrant components, humans also become indirect victims of crude petroleum oil pollution. The petroleum industry is one of the largest industries in Nigeria and the country also obtains most of its revenue from the industry. While the petroleum refinery and petrochemical industries are most desirable for national development and improved quality of life, the unwholesome and environmentally unacceptable pollution effects of the waste from these industries are causes for worry (Nwachi and Warigbani, 2013). Pollutants in the refinery wastewater include aromatic hydrocarbons, phenols, polycyclic aromatics hydrocarbons (PAHs) and heavy metals (Bako et al., 2008). Hydrocarbons are compounds whose structures are made up of hydrogen and carbon atoms. PAHs present as natural constituents in fossils fuels are formed during the incomplete combustion of organic material and are therefore presents in relatively high concentrations in products of fossil fuels refining (Wang et al., 1999). The toxicity of hydrocarbon can result in cancer, gastrointestinal infection, heart disease, neurological disorder and respiratory infection (Leachy and Rita, 1990). The treatment methods used for remediation include physical, chemical and biological processes. Physical and chemical approaches are capable of removing a broad spectrum of contaminants but the main disadvantage of these methods lie in the increased energy consumption and the need of additional chemicals (Godheja et al., 2012). Preferably, the biological method is considered because it is environmental friendly. Bioremediation is the use of biological agents such as microorganisms (bacteria, fungi and algae) and plants for the removal or detoxification of toxic substances in the environment. Hydrocabonoclastic bacteria are referred to as bacteria that can biodegrade hydrocarbon. Numerous genera of bacteria are known to be good hydrocarbon degraders and most of them belong to the genera Pseudomonas, Sphingomonas, Aeromonas, Alcaligenes, Staphylococcus, Lacticobacillus, Acinetobacter, Arthrobacter, Brevibacterium, Xanthomonas, Mycobacterium, Micrococcus, Neisseria, Enterobacter, Rhodococcus and Bacillus species (Plaza et al., 2008). Achromobacter, Actinobacter, Alcaligenes, Arthrobacter, Flavobacterium, Nocardia and Corynebacterium species are also hydrocarbon degraders (Leachy et al., 1990). This research is aimed at isolating hydrocarbonoclastic bacteria from petroleum refinery effluent and also assessing their bioremediating potentials in hydrocarbon cleanup programmes. From the aforementioned, there is no doubt that bioremediation option is gaining more acceptability over other treatment options where ever it can be applied. Great deals of literature have reported that bioremediation technologies are alternatives and or supplements to the physicochemical technologies, some of these literatures include; Less and Senior (1995); Vidali (2001); Yerushalmi et al. (2003). In addition, most of the works carried out on bioremediation were basic proof of concepts, practical oriented but not geared towards modeling and simulation or process development. Some of the works done on modeling of bioremediation processes were mainly on in-situ processes (Yaghmaei, 2002). 1.1 STATEMENT OF PROBLEMS Hydrocarbons are the world’s most widely used primary energy and fuel resources, due to the energy they produce. Apparently inevitable spillages, which occur during routine operations of crude oil production, refining, distribution and as a consequence of acute accidents, have generated continuous research interest in this field (Okoh, 2003). There had been a major shortcoming: despite the fact that microbial capability of utilizing metabolites and pollutants is virtually boundless, there are certain compounds that had been observed to be recalcitrant, and those that have not been reported to be degraded before. This leads researchers to pose questions, regarding whether new microbes and microbial capabilities for remediating these recalcitrant compounds can be isolated and identified (Huang et al., 2005). In Nigeria and Katsina state in particular, vehicular mechanical workshops often appear to be situated very close to residential and commercial areas and in some cases, near water bodies. This proximity poses a serious threat of heavy metal pollution to the inhabitants of the area. Moreover, Aboaba et al. (2009) reported that mechanical workshop soil is relatively poor for agricultural purposes, thus many abandoned mechanical workshops are left redundant with black hardened soil. 1.2 JUSTIFICATION Environment-friendly approaches have been proposed to remediate petroleum-contaminated environments. According to Pandey et al. (2009), and Paul et al. (2005), bioremediation is widely used in environmental decontamination due to its relatively lower costs and higher efciency when compared to chemical and physical remediation techniques. Bioremediation is based on the metabolization of pollutants through their complete removal, immobilization or transformation into less toxic products, which consequently mitigate their toxic efects in the environment (Díaz, 2004; Yonto and Tachibana, 2014). In phytoremediation, the interaction between plants and rhizospheric microorganisms is used to degrade, remove or stabilize contaminants in soil and water (Leahy and Colwell, 1990). 1.3 AIM To evaluate the degradation capability and kinetics of hydrocarbonoclastic bacteria found in petroleum-contaminated environments. 1.3.1 OBJECTIVES • To evaluate the degradation capability and kinetics of hydrocarbonoclastic bacteria found in petroleum-contaminated environmentsTo identify hydrocarbonoclastic bacteria from petroleum-contaminated environments. • To determine degradation ability of hydrocarbonoclastic bacteria from petroleum-contaminated environments. • To investigation of kinetic ability of hydrocarbonoclastic bacteria from petroleum-contaminated environments.