# Polyhydroxyalkanoates (PHAs): Biopolymers for Biofuel and Biorefineies
## 2 Sources of PHAs
### Microbial Synthesis of PHAs Homopolymers
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Strain** & **Carbon Source** & **DNA Manipulation** & **Final PHA** & **Manufacturer** \\ \hline _Ralstonia eutropha_ & Glucose & No & \textgreater{}80\% & Tianjin North. Food, China \\ _Acaligenes latus_ & Glucose or sucrose & No & \textgreater{}75\% & Chemie Linz, bbfF, Austria, Biomer, Germany \\ _E. coli_ & Glucose & _P3 HBCBAB_ + _rgb_ & \textgreater{}80\% & Jiang Su Nan Tian, China \\ _R. eutropha_ & Glucose + propionate & No & \textgreater{}75\% & ICI, UK, Zhejiang Tian An, China \\ _R. eutropha_ & Glucose + 1,4-BD & No & \textgreater{}75\% & Metabolix, USA Escherichia coli P3 HBCBa Tianjin \\ _E. coli_ & Glucose + 1,4-BD & _P3 HBCBAB_ & \textgreater{}75\% & Green Biosci. China \\ _R. eutropha_ & Fatty acids & _PnaC\({}_{Ac}\)_ & \textgreater{}80\% & P\&,K, Kaneka, Japan \\ _Aeromonas halyrophila_ & Lauric acid & No & \textless{}50\% & P\&, Jiangmen Biotech Cr, China \\ _A. hadyrophila_ & Lauric acid & _P3 HBCBAB_ + _rgb_ & \textgreater{}50\% & Shandong Lukang, \\ _Pseudomonas putida_, & Fatty acids & No & \textgreater{}60\% & ETH, Switzerland \\ _P. olevovans_ & Fatty acids & No & \textgreater{}50\% & Biocycles, Brazil \\ _Bacillus spp._ & Sucrose & No & \textgreater{}80\% & Tianjin North. Food, China, and Lantian Group China \\ _R. eutropha_ & Glucose & No & \textgreater{}70\% & Industrial Usina da Pedra-Acucare Alcool Brazil \\ _Burcholafaria_ sp. & Sucrose & No & \textgreater{}90\% & Chemie Linz, Austria \\ _A. latus_ & Glucose & No & \textgreater{}80\% & NingBo TianAn, China \\ _R. eutropha_ & Glucose + Lauric acid & No & 50\% & Guangdong Jiangmen Center for Biotech \\ _A. hadyrophila_ & Glucose + Lauric acid & No & 50\% & Development, China, Procter \& Gamble, USA \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Bacterial strains for pilot and large-scale production of PHAs. homopolymers. On the other hand, when PHA synthase genes _phaC1_ and _phaC2_ were exchanged with PHA synthase operon _pha_PC] from _Aeromonas hydrophilia_ 4 AK4, or _P3 HBC_ from _R. eutropha_, PHV or P3 HB were produced using valerate, butyrate, and \(\gamma\)-butylrolaton as substrates, respectively. In addition, [PERSON] and [PERSON] [54] successfully synthesized poly(3-hydroxytetradacanoate) (PHTD) using _fadB_ and _fadA_ knockout mutant of _P. putida_ KT2442. In another study, [PERSON] et al., [55] used an engineered strain of _Pseudomonas entomophila LAC23_ (designed from _P. entomophila_ L48) and deficient \(\beta\)-oxidation pathways to produce mcl PHA homopolymers. The authors found that _P. entomophila LAC23_ could be used for the synthesis of different mcl PHAs when using appropriate fatty acids as carbon sources (Figure 4) 3-hydroxytetradacanoates (3 HTD) was successfully synthesized when tetradecanoic acid was used as carbon source. Moreover, the authors were able to produce C7-C14 PHA homopolymers using _P. entomophila_ LAC23 grown on appropriate C7-C14 fatty acids. [PERSON] et al., [56] used recombinant _P. putida_ LS461, with the _phaC1 pha ZphaC2_ genes deleted, developed by involving JC123 carrying _phaC16_ PHA synthase. The resulting strain, _P. putida_ LS46123, was able to produce P3 HB or PHV PHA homopolymers when either glucose or free fatty acids were used as a carbon source. [PERSON] et al., [57] demonstrated the production of P3 HB _Rhodospseudomonas palustris_ WP3-5 when acetate and propionate were used as carbon sources. [PERSON] et al., [58] developed recombinant _E. coli_ strains by deleting _arcA_ and _ompR_; two global regulators capable of preventing the uptake and activation of exogenous fatty acids. It was found that the yields of homopolymers P3 HB, PHV, and PHHx increased significantly with only a modest increase in PHHP and PHD in _anrcA_ mutant compared to the parental strain. Thus, _P. putida_ KT2442, _P. putida_ LS461, _P. entomophila_ LAC23, _R. palustris_ WP3-5, and _E. coli_-based derivatives can produce PHAs homopolymers. Table 3 summarizes the production of PHA homopolymers by different strains.