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The Sustainable Production of Polyhydroxyalkanoates from Crude Glycerol
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Neha Rani Bhagat, Preeti Kumari, Arup Giri, Geeta Gahlawat
Genetic manipulation to change bacterial shape/morphology allows the exploitation of bacterial shapes from rods to small spheres, small to large spheres, and fibers. The advantages of doing morphological changes for PHA production include high cell density, simplified downstream processing, space enlargement to allow more PHA accumulation, and more economical bio-production [94]. To the best of our knowledge, there are no reports to date on bacterial shape engineering based PHA production from glycerol. However, several shape-related genes can be exploited for availing of crude glycerol based process benefits, where the exploitation of relevant genes modulate the bacterial length and diameter limit. Enhancement of these limits can enhance the competitiveness in bio-processing, including improvement in the effectiveness of up- and downstream processing. Thus, enhancing bacterial morphology limits can create a promising enhancement in polymer production from glycerol [94–96]. Moreover, the rigid cell wall plays a limiting role for inclusion bodies accumulation inside the bacterial cells by limiting the space, as the weak cell wall allows easy cell size expansion, thus allowing increased storage of PHA granules [94]. So, the rigidity determining genes can also be exploited for enhancing polymer accumulation and production. Other reports have shown the role of essential genes, mreB and ftsZ, encoding for the cytoskeleton protein, MreB, and the cell division protein, FtsZ, in dividing the bacterial cytoskeleton [95]. Thus, the inactivation of these genes could result in an increase in cell sizes and lengths. So, a lot of effort has been made in this area for enhancing PHA production.
Bioprocessing of recombinant proteins from Escherichia coli inclusion bodies: insights from structure-function relationship for novel applications
Published in Preparative Biochemistry & Biotechnology, 2023
Kajal Kachhawaha, Santanu Singh, Khyati Joshi, Priyanka Nain, Sumit K. Singh
The other hypothesis postulates an energy-dependent process[35] where IBs formation is believed to be a multi-step process. The series of steps includes the formation of several small aggregates that eventually agglomerates into the large aggregate size and localization in the polar ends of the bacterial cells. There is a substantial expenditure of energy in the ensuing process that is modulated by chaperones (DnaK and DnaJ), cytoskeleton (MreB), and proton motive force (pmf).[36,37] Both hypotheses (energy-dependent/energy-independent) are accepted and hold for various bioprocess conditions during large-scale heterologous protein expression in E. coli.[32,35]