Abstract
The poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) derived from cyanobacteria is an environmentally friendly biodegradable polymer. The low yield of PHBV’s production is the main hindrance to its sustainable production, and the manipulation of PHBV production processes could potentially overcome this obstacle. The present research investigated evolutionarily divergent cyanobacteria obtained from local environments of Thailand. Among the strains tested, Cyanosarcina sp. AARL T020, a hot spring cyanobacterium, showed a high rate of PHBV accumulation with a fascinating 3-hydroxyvalerate mole fraction. A two-stage cultivation strategy with sole organic carbon supplementation was successful in maximizing cyanobacterial PHBV production. The use of an optimized medium in the first stage of cultivation provided a 4.9-fold increase in biomass production. Subsequently, the addition of levulinic acid in the second stage of cultivation can induce significant biomass and PHBV production. With this strategy, the final biomass production and PHBV productivity were increased by 6.5 and 73.2 fold, respectively. The GC-MS, FTIR, and NMR analyses confirmed that the obtained PHBV consisted of two subunits of 3-hydroxyvaryrate and 3-hydroxybutyrate. Interestingly, the cyanobacterial PHBV contained a very high 3-hydroxyvalerate mole fraction (94%) exhibiting a low degree of crystallinity and expanding in processability window, which could be applied to polymers for desirable advanced applications.
Highlights
One of the interesting candidates for such plastics are polyhydroxyalkanoates (PHAs), which are a group of polyester plastics synthesized by microorganisms
PHBV was found in 18 isolates with content ranging from 0.19%
AARL T020, a hot spring cyanobacterium, has the greatest capability to accumulate the bioplastic polymer known as PHBV under twostage cultivation to achieve a high rate of biomass production
Summary
One of the interesting candidates for such plastics are polyhydroxyalkanoates (PHAs), which are a group of polyester plastics synthesized by microorganisms. Due to their fascinating properties, especially their good biocompatibility, PHAs have attracted attention as a new material in biomedical applications [1,2,3]. The different monomeric structures inside each PHA member indicates the variety of the PHA family. The most typical PHA among the 150 family members is homopolymer poly(3-hydroxybutyrate) (PHB), which is made from the 3-hydroxybutyrate (3HB) subunit [4]. The weak mechanical properties of PHB due to its high crystallinity, including brittleness and stiffness, are major disadvantages of PHB for advanced applications.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
