Microbial-derived natural bioproducts for a sustainable environment: a bioprospective for waste to wealth

Poly(hydroxyalkanoates): Production, Applications and End-of-Life Strategies–Life Cycle Assessment Nexus

“…PHAs enable bacteria to thrive under harsh environmental conditions . PHAs are mostly found in the cytoplasm of bacteria as high molecular weight intracellular granules with diameters ranging from 0.2 to 0.7 μm. , In 1926, the first PHA polymer known as polyhydroxybutyrate (PHB) was isolated by a French researcher, M. Lemoigne, while experimenting on Bacillus megaterium . , This important polymer exhibited a high melting temperature of 175 °C, high crystallinity, and high tensile strength (30–35 MPa) . After this discovery, more than 150 different hydroxy-acid monomer structures have been reported to date. , Figure a shows the general structure of PHA, whereas Figure b portrays some PHA family members, namely, 3HB (3-hydroxybutyrate), 3HV (3-hydroxyvalerate), 3HHx (3-hydroxyhexanoate), 3HO (3-hydroxyoctanoate), 3HD (3-hydroxydecanoate), and 3HDD (3-hydroxydodecanoate) …”

“…P­(3HB- co -3HV), for example, was created by adding 3-hydroxyvalerate (HV) into P­(3HB) to create a copolymer that is robust, flexible, and durable with increased thermal processing capabilities. P­(3HB- co -HHx), a mcl-HA with a higher monomeric ingredient of 3-hydroxyhexanoate, has shown enhanced thermo-mechanical properties. − It is worth mentioning that most PHAs are R-configured due to the stereospecificity of PHA synthases used in biosynthesis and are also optically active. ,, Consequently, their carboxylic and hydroxylic functional moieties are readily available for chemical functionalization …”

Optimization of Exopolysaccharide (EPS) Production by Rhodotorula mucilaginosa sp. GUMS16

“…for application in tissue engineering, is well known [1][2][3][4][5][6]. The current study, therefore, proposes the biosynthesis of valuable exopolysaccharides (EPSs), from carbon and nitrogen substrates, under the action of microbes by enabling the chemical condensation of intracellular nucleotide sugars and starter precursors in several metabolic pathways [7,8]. The biosynthesis of high molecular weight EPS incorporates the biosorption of nutrients [7,8].…”

“…The current study, therefore, proposes the biosynthesis of valuable exopolysaccharides (EPSs), from carbon and nitrogen substrates, under the action of microbes by enabling the chemical condensation of intracellular nucleotide sugars and starter precursors in several metabolic pathways [7,8]. The biosynthesis of high molecular weight EPS incorporates the biosorption of nutrients [7,8]. The produced EPSs are water-soluble long-chain branched sugar derivatives that may exist as homopolymers or heteropolymers and are characterized by a wide diversity of chemical structures [9,10].…”

“…Compared to conventional plant or algal sourced polysaccharides, EPSs are characterized by lower production costs and more efficient downstream processing, illustrated by the potential for continuous harvesting from the cell-free culture supernatant [12]. EPSs are also characterized by unique amphiphilic, gelling, biocompatibility, biodegradability, bioactivity properties have diverse biomedical, environmental and food applications [2,7,13,14]. These properties highlight that EPS may be particularly useful in tissues engineering [15,16].…”