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lower molecular mass of the polyamide. Though bio-based materials are composed
mainly or in part of many biological products provided by the biomass, it does not
support the fact that the material is biodegradable. Some of the aliphatic polyamides
are susceptible to biodegradation by microorganisms (fungi or bacteria) [31, 34,
39]. The term biodegradation was assumed to be due to the endogenous enzymatic
hydrolysis of an amide bond of polyamide. Thermophilic bacteria with optimum
growth at 55 °C isolated from soil by enrichment culture technique at 60 °C were
found to degrade PA 66 and PA 12. PA 6 and PA 66 are also degraded by some
marine bacteria such as Brevundimonas vesicularis, Bacillus cereus, Bacillus
sphaericus, and Vibrio furnissii at 35 °C. Many reports have shown the degradation
of PA 66 using white-rot fungi. These strains produce peroxidase, which has found
Fig. 8 PHBHHx production through metabolic engineering
Fig. 9 Types of polymerization depending on the synthetic procedure
M. A. Ali et al.