## 5 Biodegradability of Chitosan Derivatives and Life Cycle Assessment (LCA)
reesei_ IHEM 4122 have shown the best performance for C6-oxidized CS degradation, with final hydrolysis yields ranging from 12.9 to 36.4% (_w/w_) [245]. In summary, the biodegradation of CS and derivatives has been proved efficient, mainly thanks to the availability of a large panel of enzymes. Today, many studies focus on the improvement of these enzymes by genetic engineering, or the use of microorganisms producing chitosanolytic enzymes for degrading in situ CS bio-based products, notably in environmental and medical (CS-based systems used for drugs release) applications. The benefits of CS, including its large availability, low-cost, biocompatibility, and biodegradability, make it attractive for industrial processing in a context of multiple applications (bio-based material and adhesives, tissue engineering,... ) [253]. In the actual initiative of the establishment of the ecological impact in industrial processes development, studies of life cycle assessment (LCA) for CS utilization (from the extraction to the manufacturing product) have emerged for the last year. However, these \begin{table}
\begin{tabular}{l c c c c} \hline \hline
**Enzyme/Microorganism** & \begin{tabular}{c} **Mode of Action on** \\ **Chitosan** \\ \end{tabular} & \
\begin{tabular}{c} **Distribution of** \\ **Reaction Products** \\ \end{tabular} &
\begin{tabular}{c} **Substrate** \\ **Specificity** \\ \end{tabular} & **References** \\ \hline  
**Chitinase** &
\begin{tabular}{c} Ramdom hydrolysis \\ GlcNAc \\ \end{tabular} & Oligomers & CS & [249] \\ \hline
**Lipase** & NA &
\begin{tabular}{c} Mainly (GlcN)2 to \\ (GlcN)6, complete \\ hydrolysis (GlcM) \\ when increasing \\ reaction time \\ \end{tabular} & CS & [237] \\ \hline
**Papain** & GlcN-GlcNAcN, GlcN-GlcNAcN &
\begin{tabular}{c} GlcN, (GlcN)3\({}_{4}\) in soluble \\ fraction, and \\ oligomers in \\ insoluble fraction \\ \end{tabular} & CS & [230] \\ \hline
**Pectinase** & & & & \\ \hline \hline \end{tabular} \
\begin{tabular}{l} _Aspergillus niger_ \\ \end{tabular} & NA &
\begin{tabular}{c} Dimer to hexamer \\ with predominance \\ of dimer, oligomers \\ \end{tabular} & CS & [229,250] \\ \hline
**Lysozyme** & GlcNAc-GlcNAcNAc & NA & CS film & [231,232] \\ \hline \hline \end{tabular}  
NA: Data not available, CMC: Carboxymethylcellulose, CS: Chitosan.  
\end{table} 
Table 4: Non-exhaustive list of enzymes biodegradation chitosan. studies remain restricted to a few applications. As an example, [PERSON] et al. [219; 249] has launched an LCA study to estimate the impact of manufacturing CS from crustacean waste to a bio-based film. A comparative analysis with propylene-based films (PBF) allowed it to be demonstrated that PBF had significant disadvantages associated with the polluting nature, the consumption of higher energy, and the release of carcinogen products. In support of these data, a schematic diagram of the life cycle for the CS-based adhesive was proposed by [PERSON] et al. [1], including the presentation of the main steps leading to the production of CS-based adhesive from crustacean waste. In a different context, after demonstrating the potential of grafting phenol and catechin on a CS polymer to generate a functionalized biopolymer, the relative impact of CS derivatives was compared with other water-soluble polymers using the framework of LCA. In conclusion, LCA constitutes an indispensable approach to generating important data on CS manufacturing environmental impacts and may contribute to strengthening the stimulation/interest of the industrial sector in CS processing development.