# Polyhydroxyalkanoates (PHAs): Biopolymers for Biofuel and Biorefineies
## 2 Sources of PHAs
### Microbial Synthesis of PHAsopolymers
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{1}{c}{**Sr No.**} & \multicolumn{1}{c}{**Homopolymer**} & \multicolumn{1}{c}{**Strain or Plasmid**} & \multicolumn{1}{c}{**Involved Genes/Genes**} & \multicolumn{1}{c}{**Carbon Source**} & \multicolumn{1}{c}{**Ref.**} \\ \hline \multirow{2}{*}{1} & P3 HB & \multirow{2}{*}{_Burkholderia_ sp.} & \multirow{2}{*}{_phaC_} & \multirow{2}{*}{Gluconate and sucrose} & \multirow{2}{*}{[59]} \\  & 3H4 PE & & & & Hexanoate and octanoate, \\  & P3 HB & & & & butyrate, decanoate, lauric acid and \\
2 & PHD & & & tetradacenoic acid & \\
3 & P3 HB & _Pseudomonas_ sp. 61-3 & _P3 HB_ & Glucose & [61] \\
4 & P3 HB & _R. eutraph_ H16 & & Propionic acid & [62] \\
5 & PHHP & _P. putida_ KTOV06 & _fullBA_ & Heptanoate & [63] \\
6 & PHV & _hydroplii_ 4 AK4 & _xyb and findD_ & undecanoic acid & [64] \\
7 & P3 HB & Recombinant _E. coli_ & _Snt3A1_ & Glucose & [65] \\
8 & P4 HB & _ Bacillus cereus_ & _16S rRNA_ & Fructose, sucrose, and \\  & PHV & & & gluconate & [66] \\
9 & P3 HB & _C. necator_ and _Burkholderia sacchari_ & & Glycerol and & [67] \\  & & & Glucose & [68] \\
10 & P3 HB & Recombinant _E. coli_ & _phaCAB_ & Cheese whey & [68] \\
11 & P3 HB & _R. eutraph_ H16 and its & & & Soybean oil & [69] \\  & & recombinant strain & & & Refined sugarcane, Brown \\  & & & & sugarcane, Cocount palm sugar, & [70] \\
12 & P3 HB & _C. necator_ strain A-04 & & & rock sugar, today palm sugar and \\  & P3 HB & & & & \\  & PHY & & & & Conola oil & [71] \\
13 & PHO & _Wantersia eutraph_ & & & \\  & PHDD & & & & \\
14 & P3 HB & _Pseudomonas haplogenovna_ & Lactose, glucose, and galactose & [72] \\
15 & P3 HB & _ Bacillus firms_ NII 0830 & Pineapple Crude glycerol & [73] \\
16 & P3 HB & _ Bacillus_ sp. SV13 & & and sugarcane & [74] \\
17 & P3 HB & _C. necator_ DSM 545 & _PhaA_ & Soy cake and molasses. & [75] \\
18 & P3 HB & _C. necator_ DSM 545 & _PhaA_ & Waste glycerol & [76] \\
19 & P3 HB & _W. eutraph_ & & & Wheat based bio refinery & [77] \\
20 & P3 HB & _E. coli_ DHS \(\alpha\) and KSYH(DE) & _bHB-phaD_ under _trc_ & Tryptone & [78] \\
21 & PHV & _ Bacillus strain_ P3C18 & _16S rDNA_ & Glucose & [79] \\
22 & PHDD & _P. putida_ KTA2440 & _phaC17p_ & Sodium dodecanoate & [80] \\
23 & PHO & _P. putida_ ATCC47054 & & Glycerol and sodium octanoate & [81] \\
24 & P3 HB & _Burkholderia_ sp. AIU MSM02 & _16S rRNA_ & Mannitol & [82] \\
25 & P3 HB & _Burkholderia thailandensis_ & _mIA_, _mH8_ and _rlh_ & Cooking oil & [83] \\ \hline \hline \end{tabular}  
* 3-hydroxy-4-pentenoic acid,  
\end{table} 
Table 3: Microbial production of PHAs homopolymers. constructed a metabolically engineered _E. coli_ strain for the synthesis of P3 HB4 HB using glucose as a carbon source. The genes responsible for succinate degradation and accumulation of P3 HB in _Clostridium kluyveri_ and _R. eutropha_, respectively, were co-expressed for the synthesis of P3 HB. Additionally, the _sad_ and _gab_D genes of _E. coli_ were deleted for the synthesis of the 4 HB monomer. In another study, [PERSON] et al., [88] genetically engineered _A. lydrophila_ 4 AK4 and _P. putida_ GPp104 for the production of P3 HBHrk copolymers using gluconate and glucose as carbon sources. A truncated gene (_tesA_) encoding for cytosolic thioesterase I of _E. coli_, which is used for the conversion of acyl-ACP into free fatty acids, was incorporated into _A. lydrophila_ 4 AK4. The recombinant strain was able to synthesize 10% and 19% (\(w/w\)) P3 HBHrk when grown on gluconate and glucose, respectively. Table 4 summarizes the production of PHA copolymers by different recombinant strains. [PERSON] et al., reported the synthesis of (2-hydroxyalkanoate-_co_-3-hydroxybutyrate) (P2 HA-_co_-P3 HB) in engineered _E. coli_ using glucose as a carbon source and hydrophobic amino acids as supplementation. Four different amino acids, i.e., leucine, valine (Val), isoleucine (Ile), and phenylalanine, were introduced into the growth medium and P2 HB-_co_-P3 HB production was observed when Val was used as supplementation.