Study On Mechanism Of M25 Protein Participating In Photosynthetic Hydrogen Production Induced By NaHSO₃ In Cyanobacteria

Since the 21 st century,energy and environmental issues have gradually become the focus of attention of all countries in the world,which is closely related to the development of the whole human being.Exploring a green energy that can replace the traditional energy has become the key to solve the problem.Hydrogen energy has a unique advantage.The candidate with the greatest potential in people's eyes is favored by the majority of scientific researchers.At present,the photosynthetic hydrogen production of microalgae is the most ideal way to obtain hydrogen gas to be researched and developed.Many scientific researchers are conducting the research on the production of hydrogen by microalgae.At present,the photosynthetic hydrogen production of microalgae facing two most critical issues.One is the electron source of photosynthetic hydrogen production for hydrogen photoproduction,and another is the sensitivity of hydrogenase to oxygen.To increase the amount of photosynthetic hydrogen released by microalgae to achieve factory application For the purpose of this,it is necessary to propose more direct and effective strategies on these two issues.Since 2000,the method of sulfur deficiency proposed by Melis et al.has improved the microalgae photosynthetic hydrogen production,which has a significant effect on improving hydrogen production.It has a milestone significance in the field of microalgae photosynthetic hydrogen production,and a large number of elements such as phosphorus deficiency and nitrogen have subsequently been developed.To improve the hydrogen production of microalgae by photosynthesis,but it is not as direct and efficient as the sulfur deficiency method.In2011,Ma Weimin's research group developed Na HSO3 addition method for the first time in the hydrogen production of microalgae by photosynthesis.Without the need to change the culture medium,only by adding a certain concentration of Na HSO3 to the cultures after high light induction,the hydrogen production of microalgae has beensignificantly improved,and guaranteed algal cell activity and lowered oxygen levels.This thesis was conducted in the context of hydrogen production induced by Na HSO3.Since hydrogen production induced by Na HSO3 will also have a certain toxic effect on the photosystem ?,in order to reduce the impact of the toxicity of sodium bisulfite,mutants were screened with a high PS? activity,and this thesis intends to investigate the functional mechanism of mutant genes involved in photosynthetic hydrogen production induced by Na HSO3.Finally,a mutant with the high PS? activity was successfully screened,amplified by PCR,and then sequenced.The results indicated that the gene mutation site of the obtained mutant was m25.Then,through a series of molecular technology processing and physiological data measurement of the mutant strain ?m25,it was found that ?m25 produced more ROS than WT after a period of high light in a closed glass test tube,and the accumulation of ROS will continue to damage cells and destroy PS?,and also reduces the photosynthetic electron flow to a certain extent.In the background of Na HSO3 addition,the specific ROS-superoxide anion in the algal medium can be consumed faster by reacting with Na HSO3,thereby removing oxygen from the system more efficiently and ensuring that the algal cells enter the anaerobic state more quickly.As a consequence,hydrogenase is more activated and more efficient to produce hydrogen production by photosynthesis.The accumulation of hydrogen production in the mutant at 24 hours is about 1.7 times than that of the wild type,proving that the mutant strain with M25 protein deletion can be faster under the background of Na HSO3.It interacts with Na HSO3,consumes ROS in the system,indirectly reduces oxygen,and more efficiently realizes anaerobic photosynthetic hydrogen production.It also effectively reduces the toxic effect of Na HSO3 on photosystem ? and maintains the stability of cell photosystem ?.With more sustained oxygen release,it will not cause a completely destroyed the PSII and eventually die like sulfur-deficient culture.Using this as evidence,the molecular mechanism of the absence of M25 protein can improve the photosynthetic hydrogen production of Synechocystis sp.PCC 6803 under the background of Na HSO3 addition,hoping to provide a theoretical basis for the future research of high hydrogen production mutants.