obtained from the PHA accumulating bacterium Ralstonia eutropha strain H16 – a “model organism” in PHA research. Adding different precursor substrates is a tool for accelerating the polymerization process or for incorporating another monomric forma of PMAs. Polythioester production also includes incorporating monomeric formes of 3-hydroxybutyrate and 3-mercaptobutyrate, poly(3HB-co-3MB). The total polymer yield by R. eutropha, when 3-mercaptobutyric acid was fed as a carbon source in addition to gluconate contributed to up to 31% of the cellular dry weight. Mutants of R. eutropha with defective PHA synthase were not able to synthesize these copolymers. This demonstrated that the PHA synthase is responsible for the incorporation of 3MP and generally for biosynthesis of PTEs. If R. eutropha was cultivated in the presence of either 3-mercaptopropionic acid, 3,3’ -thiodipropionic acid (TDP) or 3,3’ -dithiodipropionic acid (DTDP), the copolymer poly- (3HB-co-3MP) was accumulated comprising molar fractions of 3MP of up to 54 mol-%. None of the sulfur-containing precursor substrates was utilized as sole carbon source for growth, thus, a second carbon source such as sodium gluconate was provided additionally to enable bacterial growth. The copolymer composition and polymer content referring to the cellular dry weight could be influenced by varying cultivation conditions and feeding regimes. When carbon sources, which are metabolized to acetyl coenzymeA(acetyl-CoA) were present in the culture medium of R. eutropha, the molar ratios of 3MP were usually less than 5 mol-%. It was observed that the total polymer yield decreased simultaneously to increasing 3MP content. However, this is not a strict rule, because other factors like the duration of fermentation also influenced the molecular weights of the accumulated polymers. 3-mercaptovalerate (3MV) were identified as constituents of PTE copolymers isolated from R. eutropha, extending the group of PTE constituents, which were referred to as 3-mercaptoalkanoates (3MA) [220, 221, 300].
2.10 Conclusion
The biopolymers contain eight groups based on their chemical structure. A ninth group could be added to include the monomers that are produced naturally and polymerized chemically such as polylactic acid. The polymeric forms of the inorganic structures are in need of more investigation. There are some unique criteria for biopolymers because they are derived from nature. They are degradable, bioavailable, compatible, renewable, safe, etc., so they are “green”. They are the main income resources for a number of countries. Their applications are diverse. Some have not yet been commercialize due to petroleum oil-based synthetic polymers. Some species of the biopolymer have attracted attention in different times. For example, polyhydroxyalkanoates attract attention after the oil crises in 1973. Being produced by different types of biological cells their control through biochemical engineering or through different molecular tools enabled better management of their production in their mother wild type host cells or in foreigner cells. We should keep the different schools of biopolymer active. The ones which not being focused on today might be in great demand in the future.
Acknowledgement
The author acknowledges his mentors Professor Dr. Alexander Steinbüchel and Professor Dr. Bernd Rhem and the entire membership of the institute of Molecular Mikrobiologie und Biotechnologie, Mathematish-Naturwissenschaftlichen Fakultät der Westfälische Wilhelms-Universitüt Münster, Germany. Special thanks to the members of lab 06. The author acknowledges the DAAD for the grant provided as a PhD scholarship.
Conflict of Interest
The author declares that there is no any kind of conflict with any concerning this chapter
References
1 1 Ali, N.E., Kaddam, L.A., Alkarib, S.Y., Kaballo, B.G., Khalid, S.A., Higawee, A., AbdElhabib, A., AlaaAldeen, A., Phillips, A.O., and Saeed, A.M. (2020). Gum Arabic (Acacia Senegal) augmented total antioxidant capacity and reduced c-reactive protein among haemodialysis patients in phase II trial. International Journal of Nephrology 2020: 7214673.
2 2 Kaddam, L., Babiker, R., Ali, S., Satti, S., Ali, N., Elamin, M., Mukhtar, M., Elnimeiri, M., and Saeed, A. (2020). Potential role of Acacia Senegal (Gum Arabic) as immunomodulatory agent among newly diagnosed COVID 19 patients: a structured summary of a protocol for a randomised, controlled, clinical trial. Trials 21 (1): 766.
3 3 Kaddam, L.A. and Kaddam, A.S. (2020). Effect of Gum Arabic (Acacia senegal) on C-reactive protein level among sickle cell anemia patients. BMC Research Notes 13 (1): 162.
4 4 Amara, A.A. (2015). Kostenlose Viral Ghosts, Bacterial Ghosts, Microbial Ghosts and More (ed. A.A. Amara). Schüling Verlage Germany. ISBN: 978-3-86523-260-1.
5 5 Ahmed, A.S., Khalil, A., Ito, Y., van Loosdrecht, M.C.M., Santoro, D., Rosso, D., and Nakhla, G. (2021). Dynamic impact of cellulose and readily biodegradable substrate on oxygen transfer efficiency in sequencing batch reactors. Water Research 190: 116724.
6 6 Chaudhary, J., Thakur, S., Sharma, M., Gupta, V.K., and Thakur, V.K. (2020). Development of biodegradable agar-agar/gelatin-based superabsorbent hydrogel as an efficient moisture-retaining agent. Biomolecules 10 (6).
7 7 Dutta, S.D., Hexiu, J., Patel, D.K., Ganguly, K., and Lim, K.T. (2021). 3D-printed bioactive and biodegradable hydrogel scaffolds of alginate/gelatin/cellulose nanocrystals for tissue engineering. International Journal of Biological Macromolecules 167: 644–658.
8 8 Hai, L., Choi, E.S., Zhai, L., Panicker, P.S., and Kim, J. (2020). Green nanocomposite made with chitin and bamboo nanofibers and its mechanical, thermal and biodegradable properties for food packaging. International Journal of Biological Macromolecules 144: 491–499.
9 9 Ichimaru, H., Mizuno, Y., Chen, X., Nishiguchi, A., and Taguchi, T. (2020). Prevention of pulmonary air leaks using a biodegradable tissue-adhesive fiber sheet based on Alaska pollock gelatin modified with decanyl groups. Biomaterials Science 9: 861–883.
10 10 Li, M., Dong, Q., Xiao, Y., Du, Q., Huselsteind, C., Zhang, T., He, X., Tian, W., and Chen, Y. (2020). A biodegradable soy protein isolate-based waterborne polyurethane composite sponge for implantable tissue engineering. Journal of Materials Science: Materials in Medicine 31 (12): 120.
11 11 Olaiya, N.G., Nuryawan, A., Oke, P.K., Khalil, H., Rizal, S., Mogaji, P.B., Sadiku, E.R., Suprakas, S.R., Farayibi, P.K., Ojijo, V., and Paridah, M.T. (2020). The role of two-step blending in the properties of starch/chitin/polylactic acid biodegradable composites for biomedical applications. Polymers (Basel) 12 (3).
12 12 Wissamitanan, T., Dechwayukul, C., Kalkornsurapranee, E., and Thongruang, W. (2020). Proper blends of biodegradable polycaprolactone and natural rubber for 3D printing. Polymers (Basel) 12 (10): 2416.
13 13 Xu, J., Sagnelli, D., Faisal, M., Perzon, A., Taresco, V., Mais, M., Giosafatto, C.V.L., Hebelstrup, K.H., Ulvskov, P., Jorgensen, B., Chen, L., Howdle, S.M., and Blennow, A. (2021). Amylose/cellulose nanofiber composites for all-natural, fully biodegradable and flexible bioplastics. Carbohydrate Polymers 253: 117277.
14 14 Zhang, J., Xu, W.R., Zhang, Y.C., Han, X.D., Chen, C., and Chen, A. (2020). In situ generated silica reinforced polyvinyl alcohol/liquefied chitin biodegradable films for food packaging. Carbohydrate Polymers 238: 116182.
15 15 Bui, A.T., Williams, B.A., Hoedt, E.C., Morrison, M., Mikkelsen, D., and Gidley, M.J. (2020). High amylose wheat starch structures display unique fermentability characteristics, microbial community shifts and enzyme degradation profiles. Food and Function 11 (6): 5635–5646.
16 16 Maevskaia, E.N., Shabunin, A.S., Dresvyanina, E.N., Dobrovol’skaya, I.P., Yudin, V.E., Paneyah, M.B., Fediuk, A.M., Sushchinskii, P.L., Smirnov, G.P., Zinoviev, E.V., and Morganti, P. (2020). Influence of the introduced chitin nanofibrils on biomedical properties of chitosan-based materials. Nanomaterials (Basel) 10 (5): 945.
