Wheat straw amendment to an oily sludge pretreated with ammonium persulfate and its impact on the indigenous mycobiota

Numerous studies have addressed the dynamics of bacterial communities in response to remediation strategies, while fungal communities, despite their potential as bioremediation agents, remain comparatively understudied. The aim of this work was to evaluate the impact of wheat straw amendment (WSA) on an oily sludge untreated and treated with ammonium persulfate on indigenous mycobiota after 60 days. Culture-independent 18S rRNA amplicon sequencing, microbial enzymatic activity and chemical parameters were analyzed. WSA on a preoxidized oily sludge promoted high total petroleum hydrocarbon (TPH) removal after 60 days, exhibiting the highest laccase activity. Fungal diversity and equitability were also recovered until reaching similar index values to those of the untreated microcosms. However, changes in fungal taxonomical groups were detected, with Eurotiales (93.4%) being replaced by Microascales (57.9%) and Sordariales (32.8%) at the end of the treatment. Our results suggest that inputs of easily assimilable organic matter in oily sludge might accelerate changes and replacement of fungal taxa, also affecting microbial colonization and, consequently, pollutant removal. These findings highlight the relevance of incorporating fungal dynamics into bioremediation strategies as a complementary approach to oily sludge treatment.