## 4 Discussion  
By selectively enriching petroleum-contaminated soil from Tombia and Bori, both in Port Harcourt, Rivers state, Nigeria, a microbial consortium capable of biodegradation solid naphthalene as a sole carbon source and growth energy was isolated. Three different bacterial taxa were discovered in the soil samples, and using a biochemical test method, they were tentatively identified as _Micrococcus_ spp., _Bacillus_ spp. and _Pseudomonas_ spp., respectively. Using lacto phenol blue dye and macroscopic and wet mount microscopy, three different hydrocarbon-using fungi--_Fusarium_ spp., _Aspergillus_ spp. and _Penicillium_ spp.--were identified. Consortium's consisted of the bacteria and fungi combined in twos with degradation rates measured in DCPIP along with the individual isolates. There was a marked increase in the rate of degradation shown by consortium's, with that of Bacillus and Pseudomonas being the most effective (they are well-known degraders of PAHs). In a study by [PERSON] et al. (2016), species of Bacillus and Pseudomonas were found to be hydrocarbon degraders, while using DCPIP as the determinant of the level of degradation, for a number of microorganisms on short- and long-chain hydrocarbons--such as car diesel oil. Naphthalene and anthracene were also found to be degraded by a number of strains discovered in the study, further confirming the usefulness of applying these microbes for biodegradation and reclamation of polluted lands within the region. Other bacteria species found to degrade these hydrocarbons were _Acinetobacter_, _Rhodococcus_ and _Gordonia_, with _Acinetobacter_ being the fastest-growing strain in waste engine oil. Fungi have been found to be more effective degraders of petroleum. A strain of _Aspergillus_ sp. was found to be the best degrader when using DCPIP to determine the degradation rate of some petroleum products (K  
Compared to the 7% in the control sample, there was an average reduction of 38.1% PAH in the soil modified with the consortium. According to the study's observations, there was a reduction of approximately 50% in all consortiums and less than 3% in the control samples. The microbial cells that promoted the development and the consumption of the fuel molecules in the medium may have died when the rate of degradation slowed down. This correlated with the 15% increase in the degradation rate by our consortium. _Microoccus_ and _Pseudomonas_, being naturally capable degraders alone, had a giant leap when combined for synergistic action. This was noted in most consortiums, including fungal isolates. According to [PERSON] [30], soils serve as reservoirs for a significant quantity of PAHs, some of which are mutagenic and/or carcinogenic and may be dangerous to human health. The addition of sewage sludge to soils increased the amount of polycyclic aromatic hydrocarbons present in those soils [31]. In the industrialized world, soil contamination by anthropogenic hydrocarbons is a problem on a worldwide scale [32]. The biological balance of aquatic environments can be severely impacted by oil spills. Exvon Valdez, Amoco Cadiz and the Prestige oil disasters are some of the most notable instances of this being seen, particularly for maritime ecosystems. Algae, invertebrates, sea animals, and birds experienced high rates of mortality in these accidents due to direct physical contact and/or exposure to hazardous chemicals produced by oil [33]. The Niger Delta region of Nigeria's soils and waters have been laid waste by petroleum pollution, with concentrations within tested soil being above regulatory limits. According to the US Environmental Protection Agency, eight of the 16 PAHs have been classified as priority pollutants and possibly carcinogenic to humans [34; 35; 36]. Despite the fact that many PAH compounds may be subject to photolysis, chemical oxidation or volatilization, [PERSON] [37] discovered that some PAH compounds may endure these processes and thereafter survive and accumulate in the environment, having hazardous, mutagenic or carcinogenic consequences.