Characterization of the bio-interaction and surface changes of paper cups treated with the fungus Aspergillus terreus using SEM and EDX

Abstract

Background: The waste from disposable paper cups is an environmental problem because it contains materials and polymer layers that interfere greatly with the speed at which it can be broken down naturally. I Bioremediation seeks to utilize metabolic activity of microorganism (fungi) and cause noticeable changes in waste materials composition and increase in waste environmental disintegration. Study Objective: The objective of this study was to assess the potential of biodeterioration by Pe. fluorescens MTCC 9768, a facultative anaerobe, on a pure and active isolate of Aspergillus terreus (a soil isolate) on paper cup pieces. Materials and Methods: Fragments of paper cup of 0.2 g was added to Potato Dextrose broth (PDB) medium and was inoculated with the isolate A. terreus. The samples were incubated for 1 month to provide enough time for the growth of the fungus and its interaction with the paper. After incubation, the samples were analyzed by SEM and EDX, with elemental mapping, to evaluate morphological and elemental modifications on the surface of the material due to the fungal treatment. Results: Scanning electron microscopy (SEM) images showed extensive fungal growth on the material, including hyphae and spore-like structures. The surface also displayed changes in texture, irregularities, and fine cracks, suggesting that fungal activity affected the paper cup. Measurements of 50 surface features in the SEM images averaged 34.11 ± 13.82 nm. The median was 32.25 nm, and measurements ranged from 11.8 to 66.0 nm. A Shapiro–Wilk test found no evidence that the measurements differed from a normal distribution (P = 0.220). Energy-dispersive X-ray (EDX) analysis identified carbon and oxygen as the main elements. Carbon made up 62.77 wt% (70.03 at%), and oxygen accounted for 33.30 wt% (27.89 at%); small amounts of sodium and aluminum were also detected. Elemental maps showed that carbon and oxygen were distributed broadly and consistently across the treated surface. Conclusion: The results reveal that the fungus *Aspergillus terreus* can proliferate over the surface of paper cups and manifest morphological alterations on their surface, along with changing the elemental makeup of the material. These findings may encourage the inclusion of A. terreus in the fungal formulations for the investigation of biopulping and bioremediation of polymeric materials and paper waste. In addition, the work underscores that further comparative studies are needed to assess the real degree of decay and the efficiency of the fungus under different conditions.