目的 建立细菌表面展示纳米级白蛋白的体系。方法 将球形芽孢杆菌表面层蛋白编码基因sllB的3′端截短后与人血清白蛋白(human serum albumin，HSA)编码基因融合，5′端与链霉抗生物素蛋白（Strep-tagI）的编码基因连接，置于大肠杆菌中表达。用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和蛋白质印迹法验证蛋白表达结果，并在透射电镜下测量表达产物的粒径。结果 将合成的Strep-tagI/ sllB1-2706 bp/Gly4Ser/HSA融合基因片段测序验证后插入原核表达质粒pET28a(+)。转化宿主菌E.coli BL21诱导表达后，全蛋白和不溶性蛋白样品经SDS-PAGE鉴定，在相对分子质量约166 000处出现特异性条带，蛋白质印迹法表明重组蛋白可与抗His-Tag 单克隆抗体结合。透射电镜下可见BL21表面有大量晶格结构，平均粒径142.3 nm。结论 将球形芽孢杆菌表面层蛋白编码基因与HSA编码基因融合后进行原核表达获得了纳米级白蛋白，为采用基因工程方法生产纳米药物和疫苗提供了一条新途径。

Objective  To establish a system for producing nano-albumin on bacterial surface.  Methods   sllB gene encoding surface layer (S-layer) protein in Bacillus sphaericus was amplified and linked with the gene coding for human serum albumin (HSA) after 3′-end truncated. Its 5′-end was linked with the gene encoding for Strep-tagI. The chimeric gene fragment was transformed into E. coli BL21. The expressed product was analyzed by SDS-PAGE, Western blot and electron microscopy. Results The chimeric gene fragment Strep-tagI/ sllB1-2706bp/Gly4Ser/HSA was confirmed by sequencing. The expression plasmid pET28a(+)-Strep-tagI/SllB1-2706bp/HSA was constructed and transformed into E.coli BL21 successfully. A specific band of Mr 166 000 was identified by SDS-PAGE and the recombinant product reacted with anti-His-Tag monoclonal antibody. The square lattice structure with average diameter of 142.3 nm was observed on the surface of E. coli BL21 under an electron microscope. Conclusions  Nano-level albumin can be produced by fusion of S-layer gene and HSA gene, which will provide a new way for production of nanomedicine and nanovaccine by genetic engineering.