Overexpression of S-Adenosylmethionine Synthetase in Recombinant Chlamydomonas for Enhanced Lipid Production

Abstract

Microalgae are attracting much attention as promising, eco-friendly producers of bioenergy due to their fast growth, absorption of carbon dioxide from the atmosphere, and production capacity in wastewater and salt water. However, microalgae can only accumulate large quantities of lipid in abiotic stress, which reduces productivity by decreasing cell growth. In this study, the strategy was investigated to increase cell viability and lipid production by overexpressing S-adenosylmethionine (SAM) synthetase (SAMS) in the microalga Chlamydomonas reinhardtii . SAM is a substance that plays an important role in various intracellular biochemical reactions, such as cell proliferation and stress response, and the overexpression of SAMS could allow cells to withstand the abiotic stress and increase productivity. Compared to wild-type C. reinhardtii , recombinant cells overexpressing SAMS grew 1.56-fold faster and produced 1.51-fold more lipids in a nitrogen-depleted medium. Furthermore, under saline-stress conditions, the survival rate and lipid accumulation were 1.56 and 2.04 times higher in the SAMS-overexpressing strain, respectively. These results suggest that the overexpression of SAMS in recombinant C. reinhardtii has high potential in the industrial-scale production of biofuels and various other high-value-added materials.

Starch‐Based Ion‐Conductive Organo‐Hydrogels with Self‐Healing, Anti‐Freezing, and High Mechanical Properties toward Strain Sensors

“…DSC was used to clarify the boundaries of the phase region and to reveal the water content of the hydrogel in different states (freezing-bound water, non-freezing water). [33] The above water state depends on the degree of interaction within the hydrogel structure. In this research, non-freezing bound water is closely associated with ions (Li + , Cl − ) through hydration and with polymers via hydrogen bonding.…”

Chitosan‐Based Smart Polymeric Hydrogels and Their Prospective Applications in Biomedicine

“…It is also chemically stable and easily processable. [82][83][84][85][86] It gives permeable and hydrophilic interfaces with body tissue, [87] provides incomparable physical, chemical, and thermal properties, [88] along with good ionic conductivity [89] and protecting agent. [86] PVA, at com-plete decomposition, produces water (H 2 O), and carbon dioxide (CO 2 ).…”

“…[142] The temperature sensitive hydrogels have three types: a) negative temperature, b) positive temperature, and c) thermally reversible. Kim et al [84] synthesized chitosan and PVA based hydrogels and observed the temperature responsive behavior of the developed hydrogels, as these samples swelled at high temperature and de-swelled when temperature was lowered down. Such hydrogels are called positive temperature hydrogels, which exhibit upper critical solution temperature.…”

“…This effect was observed by Kim et al and Singh et al who synthesized chitosan/PVA based hydrogels, which showed maximum swelling at low pH and vice-versa. [84,148] 12. Hydrogels Based on Charge…”

“…who synthesized chitosan/PVA based hydrogels, which showed maximum swelling at low pH and vice‐versa. [ 84,148 ]…”