# Evaluation of _Aspergillus flavus_ Growth on Weathered HDPE Plastics Contaminated with Diesel Fuel
## 5 Conclusions  
The results of this study confirm the potential of _Aspergillus flavus_ as an efficient fungal agent for colonizing and growing on high-density polyethylene (HDPE) surfaces contaminated with diesel fuel. The most notable mycelial development was observed on gray plastic samples with diesel residues that had undergone natural weathering for more than two years under temperate environmental conditions, such as those found in Santiago, Chile. Incubation at 30 \({}^{\circ}\)C resulted in a significant increase in both biomass  
Figure 6: Growth of _Aspergillus flavus_ on uncontaminated gray plastic samples at 20 \({}^{\circ}\)C (**A**), 25 \({}^{\circ}\)C (**B**), and 30 \({}^{\circ}\)C (**C**). and the formation of diffusible metabolites, suggesting a synergistic interaction between contaminant aging and incubation temperature. These findings are consistent with the observations of [PERSON] [10], who highlight the thermal sensitivity of fungal metabolism in bioremediation contexts. Moreover, the presence of weathered diesel-derived contaminants did not inhibit _A. flavus_ growth; rather, it appeared to stimulate metabolic activity, likely due to the increased availability of higher molecular weight oxidized compounds, which are more readily metabolized by the fungus's enzymatic machinery. This behavior aligns with previous reports describing _A. flavus_ as a microorganism with a high capacity for adaptation and degradation of recalcitrant organic pollutants [19; 24]. The methodology employed, based on kinetic analysis of radial growth and quantification of halo formation, proved robust for assessing the dynamics of fungal colonization. As previously noted by [PERSON] [24], these metrics are useful for characterizing fungal metabolic activity and its responses to various environmental conditions or contaminated substrates, providing a replicable framework for future studies. A noteworthy observation from this study was the limited colonization of white plastic samples recently contaminated with diesel (<2 months of exposure). This behavior may be explained by the higher proportion of volatile and toxic compounds, such as BTEX, present in commercial diesel, along with the higher concentration of plastic additives (e.g., antioxidants and inorganic pigments) that have not yet degraded through weathering. These factors appear to exert a stronger inhibitory effect than the contaminant itself, suggesting that the efficiency of bioremediation depends not only on the fungus and the hydrocarbon but also on the properties of the polymer substrate and its degree of environmental aging. Overall, this study provides robust experimental evidence supporting the feasibility of using _Aspergillus flavus_ in fungal-based cleaning strategies for diesel-contaminated plastic waste. The findings lay the groundwork for developing sustainable and scalable technologies that address the urgent need for eco-friendly and cost-effective solutions in managing waste from industrial and agricultural activities. Despite the controlled nature of this study, certain limitations should be considered when interpreting the results. The sample size, while consistent with preliminary biodegradation studies, may limit the statistical resolution of comparisons across treatments. Although temperature and humidity were regulated using an integrated control system within the incubator, minor fluctuations may still occur and should be acknowledged. Moreover, while the use of HDPE samples contaminated under real-world weathering conditions adds ecological realism, extrapolating laboratory outcomes to field environments remains challenging due to the complexity of biotic and abiotic interactions. Future research should explore these dynamics in situ or under semi-controlled outdoor conditions. Conceptualization, J.V., C.S.-N. and X.B. ; methodology, C.S.-N., X.B. and F.M. ; formal analysis, J.V., C.S.-N. and X.B. ; investigation, J.V., F.M. and B.M. ; data curation, J.V., C.S.-N., F.M. and X.B. ; writing--original draft preparation, J.V.