聚羟基脂肪酸酯(Polyhydroxyalkanonate,PHA)合酶是PHA合成过程中的关键酶,其活性和底物特异性决定PHA含量和单体组成.构建嵌合酶是改变PHA单体组成的一种有效方式.利用重叠延伸PCR(gene splicing by overlap extension,SOE-PCR)法,以...聚羟基脂肪酸酯(Polyhydroxyalkanonate,PHA)合酶是PHA合成过程中的关键酶,其活性和底物特异性决定PHA含量和单体组成.构建嵌合酶是改变PHA单体组成的一种有效方式.利用重叠延伸PCR(gene splicing by overlap extension,SOE-PCR)法,以富氧产碱菌和嗜水气单胞菌PHA合酶基因为亲本构建新的PHA嵌合酶.结果表明,带有新型嵌合酶基因的重组菌株AHRE可利用葡萄糖酸钠和果糖产生3HB.利用辛酸钠、月桂酸、油酸、辛酸钠和葡萄糖酸钠混合碳源,除3HB和3HHx外,还产生了新的单体组分3HO.辛酸钠和葡萄糖酸钠混合碳源发酵,PHA含量最高,达57.54%.辛酸钠为单一碳源时,3HO单体组成含量最高,占PHA总量1.932%,证明嵌合酶构建成功.这为今后利用基因工程技术改变菌株PHA单体组成提供了有效方法,为获得具有更好材料学特性的PHA奠定了工作基础.展开更多
Lipid content has an important effect on rice eating quality,but the effects of fertilizer application rate on the lipid synthesis and eating quality of rice are not well understood.Potassium(K)has a strong influence ...Lipid content has an important effect on rice eating quality,but the effects of fertilizer application rate on the lipid synthesis and eating quality of rice are not well understood.Potassium(K)has a strong influence on rice quality and the requirement for K fertilizer in rice is greater than for nitrogen(N)and phosphorus(P)fertilizers.To investigate the effects of K fertilizer on the lipid synthesis and eating quality of rice,we used Nanjing 9108(NJ9108,japonica)and IR72(indica)rice as experimental materials and four K levels:K0(0 kg ha^(-1)),K1(90 kg ha^(-1)),K2(135 kg ha^(-1))and K3(180 kg ha^(-1)).The results showed that the lipid content,free fatty acid(FFA)content,unsaturated fatty acid(UFA)content,malonyl-CoA(MCA)content,phosphatidic acid(PA)content,lipid synthesis-related enzyme activities and eating quality first increased and then decreased with increasing K in both cultivars.The maximum values were obtained under K2.However,the saturated fatty acid(SFA)content showed the opposite trend.No significant differences were found in pyruvate(PYR)content among the K treatments.The protein and oxaloacetic acid(OAA)contents and phosphoenolpyruvate carboxylase(PEPCase)activity of NJ9108 first decreased and then increased with increasing K,and the minimum values were obtained under K2;while IR72 showed the opposite trend and the maximum values were obtained under K1.Overall,increasing K optimized the fatty acid components and increased the lipid content and eating quality of rice by enhancing lipid synthesis-related enzyme activities and regulating substrate competition for lipid and protein synthesis.The optimal K application rate for lipid synthesis,eating quality and grain yield was 135 kg ha^(-1)for both cultivars.展开更多
文摘聚羟基脂肪酸酯(Polyhydroxyalkanonate,PHA)合酶是PHA合成过程中的关键酶,其活性和底物特异性决定PHA含量和单体组成.构建嵌合酶是改变PHA单体组成的一种有效方式.利用重叠延伸PCR(gene splicing by overlap extension,SOE-PCR)法,以富氧产碱菌和嗜水气单胞菌PHA合酶基因为亲本构建新的PHA嵌合酶.结果表明,带有新型嵌合酶基因的重组菌株AHRE可利用葡萄糖酸钠和果糖产生3HB.利用辛酸钠、月桂酸、油酸、辛酸钠和葡萄糖酸钠混合碳源,除3HB和3HHx外,还产生了新的单体组分3HO.辛酸钠和葡萄糖酸钠混合碳源发酵,PHA含量最高,达57.54%.辛酸钠为单一碳源时,3HO单体组成含量最高,占PHA总量1.932%,证明嵌合酶构建成功.这为今后利用基因工程技术改变菌株PHA单体组成提供了有效方法,为获得具有更好材料学特性的PHA奠定了工作基础.
基金supported by the Sichuan Science and Technology Program,China(2020YFH0146 and 2022YFH0029).
文摘Lipid content has an important effect on rice eating quality,but the effects of fertilizer application rate on the lipid synthesis and eating quality of rice are not well understood.Potassium(K)has a strong influence on rice quality and the requirement for K fertilizer in rice is greater than for nitrogen(N)and phosphorus(P)fertilizers.To investigate the effects of K fertilizer on the lipid synthesis and eating quality of rice,we used Nanjing 9108(NJ9108,japonica)and IR72(indica)rice as experimental materials and four K levels:K0(0 kg ha^(-1)),K1(90 kg ha^(-1)),K2(135 kg ha^(-1))and K3(180 kg ha^(-1)).The results showed that the lipid content,free fatty acid(FFA)content,unsaturated fatty acid(UFA)content,malonyl-CoA(MCA)content,phosphatidic acid(PA)content,lipid synthesis-related enzyme activities and eating quality first increased and then decreased with increasing K in both cultivars.The maximum values were obtained under K2.However,the saturated fatty acid(SFA)content showed the opposite trend.No significant differences were found in pyruvate(PYR)content among the K treatments.The protein and oxaloacetic acid(OAA)contents and phosphoenolpyruvate carboxylase(PEPCase)activity of NJ9108 first decreased and then increased with increasing K,and the minimum values were obtained under K2;while IR72 showed the opposite trend and the maximum values were obtained under K1.Overall,increasing K optimized the fatty acid components and increased the lipid content and eating quality of rice by enhancing lipid synthesis-related enzyme activities and regulating substrate competition for lipid and protein synthesis.The optimal K application rate for lipid synthesis,eating quality and grain yield was 135 kg ha^(-1)for both cultivars.
