The Study Of Physiological Response And Enrichment Effect Under The Stress Of As³⁺ And Se⁴⁺ Antagonism To Spirulina Platensis In Alkaline Lakes Of The Erdos Plateau

Arsenic pollution is one of the badly environmental pollution problem that global water faced. Arsenic polluted water not only influence plant’s growth and development but cause reduction of it’s nutrition and yield. Arsenic pollution seriously threatened the food safety and physical health through food chain. In this research, spirulina (Arthrospira) platensis in alkaline lake in Eordos plateau was used as material. The influences that arsenic stress on S.(A.) platensis’growth, physiological and biochemical indexes, and selenium’s detoxication to arsenic poisoning were investigated using methods that adding different concentration of sodium nitrite(As3+) or adding sodium nitrite(As3+) and sodium selenite (Se4+) together in medium to culture S. (A.) platensis that contain rich arsenic or contain rich arsenic and selenium. The accumulation and existing form of AS in S. (A.) platensis were studied on the cellular level. The main results show as follows:(1) Arsenic stress influence S. (A.) platensis’growth and biomass. Arsenic concentration between 0.01-150mg/ml can inhibit it’s growth, has no promoting effect. The half inhibitory concentration after 96h (96h EC50) is 15.27mg/L.(2) Arsenic stress to S. (A.) platensis have a influence on its absorbance spectrum. The specific performance is that wave crest of chlorophyll a and carotenoid occurs blue shift, and that of phycocyanin occurs red shift under the arsenic stress.(3) Arsenic stress to S. (A.) platensis have a influence on its photosynthetic pigment content.The specific performance is that low concentration of arsenic stress increased the content of chlorophyll and carotenoid, and high concentration of arsenic stress decreased the content of them. The content of phycocyanin decreased at both conditions.(4) Arsenic stress to S. (A.) platensis have a influence on its content of soluble proteins and alga. Low concentration of arsenic stress increased the content of soluble proteins, and high concentration of arsenic stress decreased the content of it. The content of alga decreased at both conditions.(5) Arsenic stress to S. (A.) platensis have a influence on its content of antioxidant active enzymes and MDA. The content of antioxidant enzymes like SOD, CAT, POD and GSH-PX all presented the trend of increasing first and decreasing afterwards along with the increase of arsenic stress concentration, and they presented same trend along with the culture time extension. Their sensitivity to arsenic stress presented as POD>GSH-PX>CAT>SOD. MDA content increased along with the increase of arsenic stress concentration.(6) S.(A.) platensis have a fine enrichment and transformation ability to arsenic. The content of arsenic that algae powder transformed increased along with the increase of added arsenic concentration. But its enrichment rate decreased along with the increase of added arsenic concentration.(7) Selenium have a fine improvement effect on influences that arsenic acting on S. (A.)platensis’growth and biomass. This indicated that selenium can prevent or alleviate arsenic’s toxicity effects, and effectively protect the normal growth of spirulina.This research indicated that As3+stress to S. (A.)platensis have a serious inhibition effect to its growth and biomass. S. (A.) platensis have a physiological tolerance under low concentration of As3+, algal cell didn’t appear obvious poisoning phenomenon. It, however, have a high enrichment amount to arsenic, when As3+ stress was 1mg/L, enriched arsenic content reached 2.18 mg/Kg. This amount exceeded international standard of 1.5 mg/Kg. but organic conversion rate of more than 90%. Se4+ have a fine improvement effect to As3+ stress, so culturing Se4+reached S. (A.) platensis could achieve the purpose of repairing As3+ toxic. This method could become the alternative solution to repairing As3+ toxic of spirulina distributed in Erdos Plateau where the As3+ pollution is serious.