This study investigated the ability of fungi isolated from highly contaminated soil to biodegrade polycyclic aromatic hydrocarbon (PAH) compounds, as well as the effect of several parameters on the biodegradation ability of these fungi. The isolated fungi were identified using ITS rDNA sequencing and tested using 2,6‐dichlorophinolendophenol to determine their preliminary ability to degrade crude oil. The top‐performing fungi, Aspergillus flavus and Aspergillus fumigatus, were selected to test their ability to biodegrade PAH compounds as single isolates. After 15 days of incubation, A. flavus degraded 82.7% of the total PAH compounds, with the complete degradation of six compounds, whereas A. fumigatus degraded 68.9% of the total PAHs, with four aromatic compounds completely degraded. We also tested whether different temperatures, pH, and nitrogen sources influenced the growth of A. flavus and the degradation rate. The degradation process was optimal at a temperature of 30°C, pH of 5.5, and with nitrogen in the form of yeast extract. Finally, the ability of the fungal candidate, A. flavus, to degrade PAH compounds under these optimum conditions was studied. The results showed that 95.87% of the total PAHs, including 11 aromatic compounds, were completely degraded after 15 days of incubation. This suggests that A. flavus is a potential microorganism for the degradation of PAH compounds in aqueous cultures.

Polycyclic aromatic hydrocarbons (PAHs) are environmental pollutants that are mutagenic, carcinogenic, and toxic to living organisms. Here, the ability and effectiveness of selected bacteria isolated from an oil-contaminated area in biodegrading PAHs were evaluated, and the optimal conditions conducive to bacterial PAH biodegradation were determined. Of six bacterial isolates identified based on their 16S rRNA sequences, Planomicrobium alkanoclasticum could subsist on and consume nearly all hydrocarbons according to the 2,6-dichlorophenolindophenol assay. The efficacy of this isolate at PAH biodegradation was then empirically confirmed. After 30 days of incubation, P. alkanoclasticum degraded 90.8% of the 16 PAH compounds analyzed and fully degraded eight of them. The optimum P. alkanoclasticum growth conditions were 35°C, pH 7.5, and NaNO 3 as the nitrogen source. Under these biostimulant conditions, P. alkanoclasticum degraded 91.4% of the total PAH concentration and completely decomposed seven PAHs after 15 days incubation. Hence, P. alkanoclasticum is an apt candidate for the biodegradation of PAHs and the bioremediation of sites contaminated by them.

Abstract. Al-Dossary MA, Raheem SS, Almyah MK. 2021. Molecular identification of five species of family Chaetomiaceae (Sordariomycetes, Ascomycota) from Iraqi soil. Biodiversitas 22: 1277-1284. Five ascomycetes fungi within the family Chaetomiaceae (Sordariomycetes, Ascomycota) were isolated from Iraqi agricultural soil and identified by phenotypic characteristics and molecular analysis. Chaetomium ascotrichoides and C. subaffine are reported for the first time from the Iraqi mycobiota. Amesia atrobrunnea, Collariella bostrychodes and Ovatospora brasiliensis were previously reported from Iraq as Chaetomium atrobrunneum, C. bostrychodes, and C. brasiliense respectively. All reported species were provided with brief characterizations and photographs

Shatt Al-Arab River in Basrah, Iraq represents an important source of fresh water so the current study aimed to determine the extent of pollution of the Shatt al-Arab River with some heavy metals and hydrocarbons by measuring their concentrations in sediment samples collected from different stations along the river, as well as the adoption of biomarkers represented by bacteria and fungi in determining the extents of such pollution. The results indicate that the river is contaminated with the following metals: : Ni, Cr, Zn, Pb, Cu and Cd. The total mean concentrations of heavy metals in the exchangeable part were high with 55.23, 53.76, 40.52, 33.84, 32.70 and 14.88 µg/g, respectively. The results also indicated a high concentration of hydrocarbons where the total mean was 28.52 µg/g. Bacteria and fungi represent vital indicators of heavy metals and hydrocarbons pollution in the environment. Different types of bacteria (Sphingomonas paucimobilis, Bacillus subtilis, Pseudomonas aeruginosa, Streptococcus thoraltensis, Staphylococcus lentus, Leuconostoc cremoris and Leuconostoc mesenteroides) and fungi (Aspergillus terreus, Aspergillus fumigatus, Aspergillus niger, Curvularia sp., Eurotium cristatus, Talaromyces flavus, Mucor sp., Rhizopus sp., Trichoderma sp., Dichotomomyces cejpii, and Penicillium spp.) have been isolated from the same sediment. Isolated of specific genera from bacteria and fungi like these isolated in the present study from the sediment of all studied stations reinforce the rest of the results recorded during the current study and confirms the pollution of the river with the studied pollutants.