饲料与桑叶饲喂的家蚕蚕丝品质分析

Analysis of silks from silkworms reared with artificial diet and mulberry leaves

为明确人工饲料饲喂和桑叶饲喂对家蚕蚕丝品质的影响,借助扫描电子显微镜、氨基酸分析仪、电感耦合等离子体发射光谱仪、傅里叶变换红外光谱仪、二维广角X射线衍射仪等,系统性地对2种饲喂方式获得的蚕丝的形态、组成、结构与性能进行分析。结果表明:与桑叶饲喂所获得的蚕丝相比,人工饲料饲喂所获得的蚕丝在外观、蛋白质组分方面无显著差异,而在元素含量、脯氨酸含量、二级结构、结晶度等方面存在差异;大量元素中,除Na和Si外,其余元素在人工饲料饲喂蚕丝中的含量均显著低于桑叶饲喂蚕丝,微量元素Al、Cr、B在人工饲料饲喂蚕丝中含量低于桑叶饲喂蚕丝,而Fe、Mn、Zn、Cu元素的含量反之;脯氨酸在人工饲料饲喂蚕丝中的含量显著高于桑叶饲喂蚕丝;饲料饲喂蚕丝中β转角结构含量大于桑叶饲喂蚕丝,而无规则卷曲结构含量相反,其结晶度也较桑叶饲喂蚕丝的降低5.1%;人工饲料饲喂蚕丝具有更高的平均断裂应变,而桑叶饲喂蚕丝具有更高的断裂强度,但二者差异并不显著;虽然桑叶饲喂蚕丝与人工饲料饲喂蚕丝在部分元素、氨基酸和二级结构上存在一定差异,但反映到蚕丝力学性能上其差异并不显著,说明家蚕蚕丝品质受饲喂方式的影响不显著,人工饲料饲喂具有替代桑叶饲喂家蚕的可能性。

Objective In order to understand the quality differences between silk fibers produced by artificial diet feeding and mulberry leave feeding,and to investigate the possibility of substituting artificial diet for mulberry leaves in sericulture,this research systematically analyzed the differences in morphology,composition,chemical structure,and mechanical properties between artificial diet-fed silkworm silk and mulberry leaves-fed silkworm silk.Method In this study,two groups of silkworms were fed separately with artificial diet and mulberry leaves.The silk cocoons and fibers were carefully examined for their morphological characteristics using scanning electron microscopy.In order to evaluate the composition of the silk,elemental analysis,amino acid content analysis,and sodium dodecyl sulfate polyacrylamide gel electrophoresis testing were conducted to compare the two feeding methods.Additionally,infrared absorption spectroscopy,two-dimensional wide-angle X-ray scattering(2D-WAXS),and silk tensile testing were employed to elucidate the differences in chemical structure and mechanical properties between artificial diet-fed and mulberry leaves-fed silkworm silk.Results[WTBZ]The silk with artificial diet feeding exhibited no significant differences in fiber appearance compared to the silk with mulberry leave feeding.Protein composition analysis showed that there was no difference in the type and content of silk fibroin heavy chain protein,silk fibroin light chain protein and sericin protein between the two groups of silk samples.However,notable differences were observed in terms of element content,proline content,secondary structure,and crystallinity.The element analysis revealed that,except for Na and Si,the artificial diet silk had significantly lower content of other elements compared to the mulberry leaves silk.Furthermore,artificial diet silk exhibited lower levels of trace elements such as Al,Cr,and B,while higher levels of Fe,Mn,Zn,and Cu were detected compared to the mulberry leaves silk.Analysis of amino acid content indicated a distinct variation of proline content between the two silk types,with significantly higher proline content in the artificial diet silk.The analysis of secondary structure and crystallinity demonstrated higherβ-turn content and lower random coil content in the artificial diet silk compared to the mulberry leaves silk.2D-WAXS analysis revealed lower crystallinity(60.1%)in the artificial diet silk compared to the mulberry leaves silk(65.2%).Tensile testing showed that the artificial diet silk exhibited a higher average breaking strain(19.8±8.2)%,while the mulberry leaves silk demonstrated higher breaking strength(361.6±97.2)MPa,although the difference was not statistically significant.Conclusion The study findings indicated that the observed disparities in morphology,composition,chemical structure,and mechanical properties between artificial diet-fed and mulberry leaves-fed silk were not significant,suggesting the potential of artificial diet as a substitute for mulberry leaves feeding to obtain high-quality silk fibers.The two feeding methods have no significant impact on the quality of silk produced.In addition,artificial diet offered advantages such as the potential for adding beneficial substances and avoiding harmful substances,further highlighting its suitability as a replacement for mulberry leaves in silkworm feeding.Future research may focus on incorporating beneficial substances such as metal ions or proline into artificial diets,by optimizing the formula of artificial diets and adding appropriate amounts of beneficial elements for compensation,in order to selectively improve the mechanical properties of silk and enhance the wider value of artificial diet feeding silk in sericulture.Overall,this comprehensive analysis contributes valuable insights and directions for improving artificial diet in sericulture and enhancing the quality of silk and lays a solid foundation for further promoting the strategic goal of industrialized sericulture of whole age feeding in the future.