Resumo

PEREZ-ARMENDARIZ, Beatriz et al. Filamentous fungi remove weathered hydrocarbons from polluted soil of tropical Mexico. Rev. Int. Contam. Ambient [online]. 2010, vol.26, n.3, pp.193-199. ISSN 0188-4999.

Weathered hydrocarbons from worldwide petrolic activities become more recalcitrant over time. The removal of petroleum hydrocarbons from a polluted soil [65,000 mg total petroleum hydrocarbons (TPH)/kg soil], which had been exposed to tropical environmental conditions for more than 20 years in southeast Mexico, was studied using filamentous fungi. Experiments were carried out in batch reactors (60 mL) containing a substrate consisting of polluted soil and sugar cane bagasse pith as bulk agent (80:20, w/w). Sterile and non-sterile batch reactors were inoculated with spore suspensions from Aspergillus niger, Penicillium glabrum, and Cladosporium cladosporioides. The TPH were determined at the beginning and at the end of the experiments, and the CO₂ production and accumulation were monitored by gas chromatography. All fungal species studied were associated to the removal of TPH, either on sterile or non-sterile treatments. A bioaugmentation process was observed due to the synergistic effect of C. cladosporioides and well-adapted indigenous microbial populations from the contaminated soil, as the highest removal of TPH (78.5%) and CO₂ accumulation (14.3%) were recorded in this non-sterile treatment. By contrast, the lowest TPH removal was recorded in the same species, but in the sterile treatment (62.3%) showing that the absence of adapted indigenous microbiota significantly reduced fungal metabolism (CO₂ accumulation: 9.1%), as well as the removal of TPH. Patterns of CO₂ accumulation and TPH removal in other treatments suggested interspecific competence between fungal species and the adapted indigenous microbiota.

Palavras-chave : Aspergillus; bioaugmentation; Cladosporium; filamentous fungi; Penicillium; total petroleum hydrocarbons (TPH) removal; tropical Mexico.