不同品种豇豆发酵过程中质构品质变化及产植物细胞壁降解酶微生物种类分析

Texture Changes and Plant Cell Wall Degrading Enzymes Producing Microorganism Diversity in Different Varieties of Cowpea during Fermentation

以4种不同品种豇豆为研究对象,探究发酵过程中菌群和质构特性变化,分析造成不同品种发酵豇豆软腐的产植物细胞壁降解酶(Plant cell wall degradation enzymes,PCWDEs)微生物的主要种类。采用质构分析仪测定发酵过程中豇豆质构的变化,用鉴别培养基筛选产PCWDEs微生物并进行16S rDNA或18S rDNA分子生物学鉴定。结果表明:豇豆品种A(成豇10号)在发酵过程中表现出的质构品质最好,与豇豆品种A相比,豆品种B(红嘴胖豇)、品种C(成豇9号)和品种D(挂面红)的硬度、弹性、咀嚼力下降得更快,尤其是豇豆品种B。对产PCWDES微生物种类分析得知,品种B发酵豇豆中产PCWDEs微生物数量和种类最多且产酶类别多样,微生物分属于肠杆菌属(Enterobacter)、柠檬酸杆菌属(Citrobacter)、假单胞菌属(Pseudomonas)、葡萄球菌属(Staphylococcus)、粘菌属(Myroides)、泛菌属(Pantoea)和克雷伯氏菌属(Klebsiella)等属;品种A、品种C、品种D中产PCWDEs微生物及产酶种类较少,仅在品种D中发现产PCWDEs的解鸟氨酸拉乌尔菌(Raoultella ornithinolytica); 4种发酵豇豆中均分离得到产蛋白酶的植物乳杆菌(Lactobacillus plantarum)和产淀粉酶的异常威克汉姆酵母(Wickerhamomyces anomalus)。综上所述,不同品种豇豆在发酵过程中微生物群体及质构品质变化具有品种特异性,发酵后期豇豆的软腐与产PCWDEs微生物的种类和数量有关。

Four different varieties of cowpea were studied as the research object,and the changes of microbial flora and texture properties were explored.The main typical species of plant cell wall degrading enzymes(PCWDEs)caused by different varieties of fermented cowpea soft rot were analyzed.The textures of fermented cowpea were determined by texture analyzer.The PCWDEs producing agents were separated by differential plates and identified through the 16S/18S rDNA sequencing.The results showed that cowpea A presented the best texture quality during the whole fermenting process.The hardness,springness and chewiness of cowpea B,cowpea C,cowpea D were destroyed faster than cowpea A in fermentation process,especially cowpea B.Cell wall degrading enzymes(PCWDEs)producing isolates were selected.The results presented that the fermented cowpea B harbored the most numbers and varieties of PCWDEs producing microorganisms,which belonged to Enterobacter,Citrobacter,Pseudomonas,Staphylococcus,Myroides,Pantoea and Klebsiella.The PCWDEs microorganisms in fermented cowpea A,cowpea C and cowpea D were less than cowpea B.Only Raoultella ornithinolytica presented in cowpea D.Lactobacillus plantarum producing protease and Wickerhamomyces anomalus producing amylase were found in four fermented cowpeas.The present study showed that the texture and microbial changes during the fermentation in different fermented cowpeas presented respective specificities.The softrot of fermented cowpeas was related to the number and variety of PCWDEs producing agents in the later fermented process.