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Genetic Engineering in Improving the Output of Algal Biorefinery
Published in Shashi Kant Bhatia, Sanjeet Mehariya, Obulisamy Parthiba Karthikeyan, Algal Biorefineries and the Circular Bioeconomy, 2022
Yogita Sharma, Ameesh Dev Singh, Sanjeet Mehariya, Obulisamy Parthiba Karthikeyan, Gajendra Pal Singh, Chandra Pal Singh, Antonio Molino
Other organic compounds such as acid derivatives, like cinnamic acid, p-coumaric acid, and caffeic acid have also been synthesized from microalgal cells. These compounds have antimicrobial and anti-inflammatory properties that can be exploited for human as well as animal use. Phenylpropanoid is involved in the formation of p-coumaric acid. E. Bin Gao et al. (2021), in their work to enhance p-coumaric acid production in Synechocystis sp. PCC6803, exogenously expressed phenylalanine ammonia-lyase (PAL) gene and the cinnamic acid 4-hydroxylase (C4H) gene using the Pcpc560 promoter along with knocking out the endogenous arogenate dehydrogenase gene leading to an overall synthesis of 1.2mM of p-coumaric acid in the mutants (Gao et al., 2021). Another acid derivative, succinate, was found to be overproduced from Synechocystis sp. PCC6803 by overexpressing the rate-determining enzyme, phosphoenolpyruvate carboxylase gene (ppc) of glycolysis pathway. The CO2 assimilated in light was catabolized to succinate under dark anoxic conditions in glycolysis and TCA cycle. This was identified by using labeled NaH13CO3 (Hasunuma et al., 2016).
Serratia marcescens
Published in Yoshikatsu Murooka, Tadayuki Imanaka, Recombinant Microbes for Industrial and Agricultural Applications, 2020
The foregoing increases in productivity depend on the enhancement of the precursor supply by the improvement of culture conditions. Similar increases are obtained by genetic approaches. l-Threonine is synthesized from aspartate, which is formed from phosphoenolpyruvate, an intermediate in glycolysis, through oxaloacetate, a member of the tricarboxylic acid (TCA) cycle. The rate-limiting enzyme for aspartate synthesis is phosphoenolpyruvate carboxylase, encoded by the ppc gene. There was a possibility that the enhancement of this enzyme activity might elevate the productivity of T-1165, a threonine-producing strain; therefore, we cloned the ppc gene from E. coli into a low-copy-number plasmid [42]. We used the E. coli gene because this bacterium showed a much higher enzyme activity than S. marcescens. The introduction of the resultant plasmid, pSTlOl, into T-l 165 increased the production from 39 to 52 g/L in a conventional medium and from 52 to 63 g/L in a modified medium. Thus, the genetic alteration of precursor metabolism did enhance the productivity, as expected.
Modular Systems in Coal Industry
Published in Yatish T. Shah, Modular Systems for Energy and Fuel Recovery and Conversion, 2019
This study by Park et al. [45] shows the preparation and application of modular biomimetic carbon dioxide utilization of multi- and chemo-enzymatic systems for long-term stable continuous operation. The system is assembled by enzyme immobilization on the silica-shell surface of the hybrid microbeads forming stabilized carbonic anhydrase (CA) and phosphoenolpyruvate carboxylase (PEPCase) microbeads, respectively. The CA and PEPCase microbeads were very stable, preserving 85% of their initial activity over more than 30 days. In addition, both hybrid microbeads were repeatedly used successfully for more than 20 cycles of reaction, and they still remained active with facile magnetic separability at room temperature. In addition, the CA and PEPCase microbeads were employed within a modular enzyme reactor system to show its long-term and stable use in the continuous and/or simultaneous production of oxaloacetate (OAA) and CaCO3 from a continuously supplied CO2 solution. It was found that the production of OAA and CaCO3 was stable for more than 24 h and 6 days, respectively. This is a demonstration study of both repeated-batch and continuous modes for stable CO2 utilization and sequestration biomimetically by using stabilized multi- and chemo-enzymatic modular catalysis systems [45].
Isolation of Cadmium and Lead Tolerant Plant Growth Promoting Rhizobacteria: Lysinibacillus varians and Pseudomonas putida from Indian Agricultural Soil
Published in Soil and Sediment Contamination: An International Journal, 2019
Amit Kumar Pal, Chandan Sengupta
Cadmium (Cd) is one of the toxic heavy metal to the entire organism including plant and animal (Smiri et al. 2010). Cadmium act as growth inhibitor, activator or inhibitor of enzymes, hamper plant water relationship and ion metabolism, inhibitor of chlorophyll biosynthesis, slowdown Calvin cycle by slowing various enzymes, interrupted O2 evolution from PS-II, alter electron flow between PS-I and PS-II, show inhibitory effect on many enzymes such as Fructose 6 phosphate kinase, Fructose bis-phosphatase, Ribulose-1,5-bisphosphate carboxylase oxygenase, Phosphoenolpyruvate carboxylase, NADP+ glyceraldehyde-3-phosphate dehydrogenase and Carbonic anhydrase (Krantev, Yordanova, and Popova 2006; Popova et al. 2009). So, different types of morphological (Burzyński and Żurek 2007; López-Millán et al. 2009), physiological or biochemical (Krantev, Yordanova, and Popova 2006; Popova et al., 2009) and photochemical (Haag-Kerwer et al. 1999; Perfus‐Barbeoch et al. 2002; Sandalio et al. 2001; Smiri et al. 2010) changes in plant body can be observed due to cadmium toxicity. Cd exposure to the plants leads to easy availability into the food chain and malfunctioned human health includes renal failure, bone demineralization, osteoporosis, liver cirrhosis, Itai-Itai disease, etc. (Abbas et al. 2014; Aoshima 2016; Clemens et al. 2013). Lead (Pb) is another poisonous heavy metal for its long-term persistence in the environment and can cause anemia, renal failure, reproductive impairment, and neurodegenerative damage, etc. (Eslami et al. 2011). Pb adversely affects the seed germination, root and shoot growth, biomass production, ion distribution and chlorophyll content of plants (He 1990; Trvedi and Erdei 1992).
From second generation feed-stocks to innovative fermentation and downstream techniques for succinic acid production
Published in Critical Reviews in Environmental Science and Technology, 2020
Enrico Mancini, Seyed Soheil Mansouri, Krist V. Gernaey, Jianquan Luo, Manuel Pinelo
The reductive TCA cycle, also identified as the fermentative pathway, occurs under anaerobic conditions where the enzyme phosphoenolpyruvate carboxylase (PEPC) fixes CO2 into a molecule of phosphoenolpyruvate (PEP), converting the PEP to oxaloacetate (OAA). Subsequently, the fermentative pathway converts OAA into malate, fumarate and finally succinate. Therefore 2 moles of NADH and a mole of CO2 are needed for every mole of SA produced from PEP (Figure 5).