The Influence Of PH On The Activities Of The Key Enzyme Of The Krebs Cycle In Suillus Luteus

Suillus luteus is a kind of ectomycorrhizal fungi,and has high nutritional and medical value. The metabolism of the fungi can be influenced by the pH in the culture,it is able to regulate pH in environment by secreting acidic substances. However, it is not clear that how the environment pH affects Krebs cycle in it. In this study,we study the influence of pH conditions in aerial culture on its growth and metabolism. The results showed that under the aerial culture conditions, the best growth condition of pH is4.5and5.5. the optimum pH values of reaction of citrate synthase (CS), isocitrate dehydrogenase (IDH) and a-ketoglutarate dehydrogenase complex (a-KGDH) were7.0、7.6and8.0,respectively. The enzyme activities were6.059U/g fresh mycelium (86U/mg protein),15.691U/g fresh mycelium (222U/mg protein),6.865U/g fresh mycelium (68U/mg protein).We also found that different pH condition had great influence on enzyme activity in aerial culture. The highest enzyme activity in per unit mass of fresh mycelium of CS was under the pH4.5condition, as for IDH and a-KGDH, the value was7.0and5.5respectively. Under the different pH condition,the key enzyme have different activities,overall,the Krebs cycle in the mycelium was more vigorous.