# Microbial Depolymerization of Epoxy Resins: A Novel Approach to a Complex Challenge
## 3 Results
### Microbiological Water
#### 3.2.3 New Samples Incubated for Three Months in the Microbiological Water  
Small epoxy cubes were incubated in the microbiological water for three months. Morphological ESEM mapping was performed before and after incubation on the same area to obtain more information on the colonization dynamics of the microbiome present in this aquatic ecosystem. Results revealed that, after three months, two types of microbes were presents on the sample surface. Colonies of quasi-spherical microbial cells with a diameter of roughly 10 \(\upmu\)m similar to the one present in the older samples were identified in several area of the samples after incubation. Some filamentous matrix was also visible between the cells and attached to the epoxy surface (Figure S6). Furthermore, isolated filamentous structures were also detected in other areas of the same sample. These structures were not present on the samples before incubation. Hence, it can be concluded that these are the first colonizer of the epoxy samples and that the microbial community present on this aquatic ecosystem is still active. In fact, filamentous matrices are attached to the surface and between the cells, which rules out the possibility that these microbial structures were present in the water and simply settled on the surface by gravity. In order to test the depolymerization potential of the microbial communities present on the microbiological water, larger epoxy samples were also incubated for 3 months, and several analyses were carried out. Overall, differences between data collected before and after incubation was detected for all the samples including the controls. Therefore, to facilitate data interpretation, the difference between data collected on samples before and after exposure was calculated for the controls and the samples incubated in the microbiological water (microbes). Concerning the carbonyl index, no significant differences were detected (Figure 9a). In contrast, contact angle data show a slight, but significant difference  
Figure 8: Photos of some microbes during the isolation process. (**a**) Fungal green and powdery colony partially growing on epoxy sample; (**b**) with-grey powdery fungal colony partially growing on epoxy sample; (**c**) black fungal condiophores growing from the epoxy sample; (**d**) bacterial colonies growing on the selective medium containing epoxy powder. in the average from the values of control and samples treated with microbiological water. Surprisingly, difference in contact angle data between before and after incubation were higher in controls samples comparing with the treated ones. On the other hand, colorimetric data showed some interesting differences in terms of visual appearance. In Figure 10, all the tested color coordinates (L*, a* and b*) showed significant differences between controls and samples incubated with microbes. This indicated a change in the properties of the epoxy induced by incubation in the microbiological water. Explicitly, difference in brightness values increased from 3.43 for the controls samples to 3.47 for the samples treated with microbiological water. The same trend could be noticed for a* and b* color coordinates. Indeed a higher difference of both these values was detected for samples treated with microbiological water compared with the controls (Figure 10b,c). Comparing these data with the colorimetric plot (Figure S7) it can be clearly seen a general shift of the color coordinates measured on the samples after treatment toward yellow and red (less green and less blue). This change in color coordinates measured on the samples after treatment was more pronounced in samples incubated in microbiological water. However, it is notable that, even though these changes are statistically significant, they are minimal changes, which are not perceivable to the human eye. Together, these results are clearly not sufficient to draw any conclusion about microbial depolymerization of the epoxy surface. To obtain more significant results, samples should be incubated for a longer time.