A higher in value biopolymer product of polyhydroxyalkanoates (PHAs) synthesized by Alcaligenes latus in batch/repeated batch fermentation processes of sugar cane juice

Biodegradable polymers of polyhydroxyalkanoates (PHAs) are produced and accumulated in various microorganisms, especially in bacteria. In this work, a cheap agricultural sugar cane juice (SCJ) was used as a carbon source by Alcaligenes latus during its growth coupled with the production of PHAs via batch/ repeated batch fermentation processes. In batch fermentation, the maximum PHAs and PHAs content of 2.20 ± 0.14 g/L and 53.65 % were obtained within 24 h while in the case of four cycles of repeated batch fermentation, the PHAs productivity was reached at about 0.21 g/L·h that was 2.33 fold when compared to the first batch fermentation (0.09 g/L·h). Interestingly, the duration in each cycle or in batch operation during repeated batch fermentation was shorter than that found in the batch fermentation and PHAs productivity was also improved. After PHAs recovery, the physicochemical properties of nuclear magnetic resonance (NMR) and a fourier transform infrared (FTIR) spectrogram were characterized and revealed to be in full agreement with the standard polymer of polyhydroxybutyrate (PHB).