Growth associated polyhydroxybutyrate production by the novel Zobellellae tiwanensis strain DD5 from banana peels under submerged fermentation.

In view of environmental pollution by fossil fuel-based plastics, it has become imperative to find out an alternative biodegradable plastic for sustainability. In this context, polyhydroxy butyrate (PHB) production was carried out by the Zobellella sp. DD5 using inexpensive banana peels as the carbon source. Under optimized condition, 1.13 g/L (47.3%) of PHB was produced by the bacteria in growth associated mechanism. The CO group of PHB was detected from the high intense absorption band (1719 cm-1) of FTIR spectroscopic analysis. NMR and GC-MS results are also identical with the chemical shift signal CH, CH2 and CH3 group of PHB. The PHB is crystalline in nature and degree of crystallinity (Xc) - 34.38%, melting temperature (Tm) - 169 °C, thermal decomposition temperature (Td) - 248 °C as detected by XRD and DTA respectively. Rough surface morphology of PHB film was validated by AFM and SEM imaging that improves biodegradability of the PHB. The Young's modulus, tensile strength and elongation at break depicted hard and brittle nature of PHB. Fluorescence-activated cell sorting (FACS) confirmed cytocompatibility of PHB at 500 µg/mL in human embryonic kidney (HEK-293) cell line. The non-cytotoxic PHB can be used for various biomedical and agricultural applications in future.

Structural and thermal characterization of PHAs produced by Lysinibacillus sp. through submerged fermentation process.

In this investigation an attempt has been made to characterize and identify Lysinibacillus sp. 3HHX by 16S-rDNA sequencing. The bacterium exhibited occurrence of PHAs granules on an average 11±1 per cell of 1.0µm length and breadth 0.72µm, revealed from TEM studies. Under optimized condition, 4.006gm/L of PHAs was extracted using hypochlorite digestion and multi-solvent extraction process. PhaC gene of ∼540bp and higher PHA synthase activity was detected at 48h of cultivation. The extracted PHAs was structurally characterized by GC-MS and 1H NMR reported to be P(3HB-co-3HDD-co-3HTD) and amorphous in nature with 112°C melting point, -11.0°C glass transition point and 114.76°C decomposition temperature detected by DSC & TGA respectively. The C/O of biopolymer disc was 1:65 as revealed from C1s and O1s spectra of XPS, that was completely biodegradable within 30 days. This biopolymer was observed to be non-cytotoxic to NIH 3T3 mouse fibroblast cells. The report is of its kind in establishing the abilities of Lysinibacillus sp. 3HHX for non-growth associated PHA co-polymer production. Moreover the biocompatible and biodegradable nature of the biopolymer conferred to its substantial biomedical applications.