With growing environmental concerns over plastic pollution, polyhydroxyalkanoates (PHAs) have recently gained significant attention as promising biodegradable polymers to substitute petroleum-based plastics. In this work, non-edible Cerbera odollam oil was employed as a renewable carbon source for PHA production to improve the economic competitiveness and environmental sustainability of the process. The optimization and mechanism of PHA production from C. odollam oil using Pseudomonas resinovorans DSM 21078 were presented. Through response surface methodology, the optimal condition for PHA production was 0.3 g/L urea concentration, 17.52 g/L oil concentration, and 10.46% (v/v) inoculum size. Results showed that a maximum PHA concentration of 0.50 g/L (with a polymer content of 26.0%) was attained at this optimal condition. The product was composed of 1.3% 3-hydroxybutyrate (3HB), 9.2% 3-hydroxyhexanoate (3HHx), 43.3% 3-hydroxyoctanoate (3HO), 32.0% 3-hydroxydecanoate (3HD), 11.9% 3-hydroxydodecanoate (3HDD), and 2.2% 3-hydroxytetradecanoate (3HTD). The PHA polymers exhibited adhesive, soft, and amorphous properties at room temperature, with high thermal stability, making them desirable for polymer processing. From the mechanism proposed, it was inferred that P. resinovorans DSM 21078 produces longer-chain PHA monomers mainly through the direct β-oxidation of long-chain fatty acids and shorter-chain monomers via the de novo fatty acid synthesis pathway when oil-based substrates are utilized. The findings from this work could pave the way for new paradigms that significantly enhance future research in the development of highly efficient oil resource valorization technologies to produce PHAs with intriguing properties, thereby contributing to the commercial success of sustainable bioplastics as an effective environmental management solution.
Mango (Mangifera indica L.) is an economically important fruit. However, the marketability of mango is affected by the perishable nature and short shelf-life of the fruit. Therefore, a better understanding of the mango ripening process is of great importance towards extending its postharvest shelf life. Proteomics is a powerful tool that can be used to elucidate the complex ripening process at the cellular and molecular levels. This study utilized 2-dimensional gel electrophoresis (2D-GE) coupled with MALDI-TOF/TOF to identify differentially abundant proteins during the ripening process of the two varieties of tropical mango, Mangifera indica cv. 'Chokanan' and Mangifera indica cv 'Golden Phoenix'. The comparative analysis between the ripe and unripe stages of mango fruit mesocarp revealed that the differentially abundant proteins identified could be grouped into the three categories namely, ethylene synthesis and aromatic volatiles, cell wall degradation and stress-response proteins. There was an additional category for differential proteins identified from the 'Chokanan' variety namely, energy and carbohydrate metabolism. However, of all the differential proteins identified, only methionine gamma-lyase was found in both 'Chokanan' and 'Golden Phoenix' varieties. Six differential proteins were selected from each variety for validation by analysing their respective transcript expression using reverse transcription-quantitative PCR (RT-qPCR). The results revealed that two genes namely, glutathione S-transferase (GST) and alpha-1,4 glucan phosphorylase (AGP) were found to express in concordant with protein abundant. The findings will provide an insight into the fruit ripening process of different varieties of mango fruits, which is important for postharvest management.
The Rab GTPase family plays a vital role in several plant physiological processes including fruit ripening. Fruit softening during ripening involves trafficking of cell wall polymers and enzymes between cellular compartments. Mango, an economically important fruit crop, is known for its delicious taste, exotic flavour and nutritional value. So far, there is a paucity of information on the mango Rab GTPase family. In this study, 23 genes encoding Rab proteins were identified in mango by a comprehensive in silico approach. Sequence alignment and similarity tree analysis with the model plant Arabidopsis as a reference enabled the bona fide assignment of the deduced mango proteins to classify into eight subfamilies. Expression analysis by RNA-Sequencing (RNA-Seq) showed that the Rab genes were differentially expressed in ripe and unripe mangoes suggesting the involvement of vesicle trafficking during ripening. Interaction analysis showed that the proteins involved in vesicle trafficking and cell wall softening were interconnected providing further evidence of the involvement of the Rab GTPases in fruit softening. Correlation analyses showed a significant relationship between the expression level of the RabA3 and RabA4 genes and fruit firmness at the unripe stage of the mango varieties suggesting that the differences in gene expression level might be associated with the contrasting firmness of these varieties. This study will not only provide new insights into the complexity of the ripening-regulated molecular mechanism but also facilitate the identification of potential Rab GTPases to address excessive fruit softening.
Mango is a highly perishable seasonal fruit and large quantities are wasted during the peak season as a result of poor postharvest handling procedures. Processing surplus mango fruits into flour to be used as a functional ingredient appears to be a good preservation method to ensure its extended consumption.