Collagen peptide provides Streptomyces coelicolor CGMCC 4.7172 with abundant precursors for enhancing undecylprodigiosin production

Effective and ecofriendly converting biomass to chemicals is important for sustainable engineering based on the foreseeable shortage of fossil resources.Undecylprodigiosin(UP)is a promising antibiotic,but the direct feeding of pure precursor amino acids makes it costly for large-scale production.Here,collagen peptide(CP),a renewable animal-derived biomass contains abundant precursor amino acids of UP.CP can act as carbon and nitrogen source for the growth of Streptomyces coelicolor CGMCC 4.7172.The plant biomasses including soybean meal,wheat bran,and malt extract were unsuitable for UP prodution.However,365.40µg/L UP was detected after 24 h in the media containing CP,and its highest concentration reached 1198.01µg/L.UP was also detected in the media containing meat hydrolysates of domestic animals,but its initial production time was delayed,and final concentration was lower than that in the medium containing CP only.Compared the fermentation performances of CP and other proteins,CP has a special superiority for UP production.These results revealed that UP biosynthesis may be dependent on amino acid availability of substrates and CP is beneficial for UP production because of its specific amino acid composition.

十一烷基灵菌红素检测方法的研究

目的建立可以灵敏、准确和可靠地检测十一烷基灵菌红素(undecylprodigiosin,UP)含量的方法,为UP进一步的理论研究和工业应用提供支持。方法分别采用分光光度计和高效液相色谱(HPLC),构建UP的定量检测方法。结果基于HPLC的分析条件的优化,发现UP在甲醇-甲酸水溶液梯度洗脱体系下的理论塔板数高于10000,表明UP可以得到有效的分离和检测。分光光度法测定UP的线性范围为0.25~10mg/L,而采用HPLC法时线性范围则可扩展到0.1~30mg/L。HPLC法测得的UP含量比分光光度法更为精确。HPLC法的检测限为0.025mg/L,加标回收率为98.51%~105.03%。HPLC法还具有精密度高、重复性好、稳定性强的特点。结论HPLC法可以作为UP的定量分析方法。

大肠杆菌乙酰-CoA羧化酶基因异源表达对变铅青链霉菌次级代谢的影响

克隆组装了大肠杆菌的乙酰-CoA羧化酶基因acc,以研究其异源表达对变铅青链霉菌中2种"沉默"抗生素放线紫红素和十一烷基灵菌红素合成的影响。大肠杆菌ACC由4个基因编码,通过PCR扩增4个基因,并通过重叠延伸PCR加上ermE启动子,构建得到4个重组基因;再将重组基因依次组装得到异源表达质粒pHLZ11,接合转移到变铅青链霉菌中进行异源表达。结果显示:含有异源表达质粒的变铅青链霉菌接合转移子能合成放线紫红素而十一烷基灵菌红素产量提高。表明大肠杆菌acc基因异源表达能够激活变铅青链霉菌沉默抗生素的合成,并提高已有抗生素产量。

壮观链霉菌红色素的结构解析及其稳定性研究

为探究壮观链霉菌AX-3所产生的天然红色素的应用前景,对其进行了结构解析及溶解性和稳定性研究。通过全波长扫描、红外光谱、质谱、核磁共振氢谱分析,推测该红色素为十一烷基灵菌红素。性质研究结果表明,该色素最大吸收波长为532 nm;不溶于水,易溶于四氢呋喃,溶于乙醇、乙酸乙酯、丙酮、二氯甲烷、甲醇、丙三醇;在强酸、中性和弱碱环境下稳定,在强碱环境下,随着碱性的增强,色素稳定性逐渐降低;在4~90℃热稳定性较好;光照对色素稳定性有影响,太阳光比紫外光和日光灯光的影响更大;金属离子Ca^(2+)、Al^(3+)、Mg^(2+)对色素稳定性影响较小,Fe^(2+)对色素有增色作用,Zn^(2+)、Cu^(2+)会降低色素的稳定性,其中Cu^(2+)对色素稳定性影响最大;维生素C、蔗糖、柠檬酸、氯化钠、磷酸二氢钾和山梨酸钾对该色素稳定性无明显影响。