优势乳酸发酵菌株筛选、鉴定及对发酵萝卜风味品质的影响

Screening of dominant lactic acid fermentation strains,identification and effect on flavor quality of fermented radish

[目的]筛选优良乳酸菌菌株以构建萝卜专用的泡菜发酵菌种。[方法]从不同地区收集萝卜老坛泡菜母水,采用稀释涂布法从泡菜母水中分离乳酸菌,通过生理鉴定、形态学鉴定(菌落观察和,革兰氏染色法)、16S rDNA基因测序和系统发育树构建确定种类并对其生长特性、耐受能力和风味物质进行检测。[结果]分离筛选结合生理鉴定共获得120株菌株,其菌落为圆形凸起,镜检呈杆状或球状且均为革兰氏阳性菌。进一步通过产酸能力测试获得15株产酸能力较强的菌株。分子鉴定表明,1株为芽孢杆菌属、13株为植物乳杆菌属,1株为戊糖片球菌属。对不同类型发酵菌株进行生长特性分析,发现菌株LA-8与LA-11的生长速度比其他菌株快;菌株LA-8的产酸能力强,耐10%盐和15%蔗糖。4株不同类型菌株均具有较强的降解亚硝酸盐能力。萝卜发酵初试试验表明,菌株LA-8和LA-11的发酵能力较强,产酸速度快。4株不同类型乳酸菌发酵萝卜所产生的挥发性物质存在差异。[结论]从不同地区萝卜老坛泡菜母水中筛选得到3个不同类型的优势发酵菌,可作为萝卜泡菜产业生产的菌种来源。

[Objective]This study aimed to screen the excellent lactic acid bacteria strains to construct a special pickle fermentation strain for radish.[Methods]Lactic acid bacteria were isolated from the pickle brines of Laotan sauerkraut collected from different regions by dilution coating method.The species were determined by physiological identification,morphological identification(colony observation,Gram staining),16S rDNA gene sequencing and phylogenetic tree construction,and their growth characteristics,tolerance and flavor substances were detected.[Results]Isolation,screening,and physiological identification yielded 120 colonies of round,convex bacteria,which appeared rod-shaped or spherical under the microscope and were all Gram-positive strains.Further 15 strains with high acid production capacity were obtained by acid production capacity test.By molecular sequencing,1 strain was identified as Bacillus,13 strains as Lactobacillus plantarum and 1 strain as Pediococcus pentosus.Among them,L.plantarum was the dominant lactic acid fermentation strain screened in Sichuan,Chongqing,Liaoning,Guizhou,Hunan and Nanping of Hubei province,and Bacillus and P.pentosus were screened in Tuanbao area of northern Hubei Province.The growth characteristics of different types of fermentation strains were analyzed,and the growth rate of strains LA-8 and LA-11 was faster than other strains;Strain LA-8 had the highest acid production capacity,and was resistant to 10%salt and 15%sucrose.All four strains had the ability to degrade nitrite.Strains LA-4 and LA-6 were able to produce 15%sucrose,and their growth rate and acid-producing capacity were slightly lower than that of L.plantarum.The initial experiment of radish fermentation showed that LA-8 and LA-11 had stronger fermentation ability and faster acid production.The electronic nose detection technology was used to detect the fermentation flavor of radish,and it was found that the volatile substances produced by four strains of different types of lactic acid bacteria were different.[Conclusion]Three different types of dominant fermentation strains were screened from the mother water of radish laotan pickle in different regions,which could be further used as the source of strains for the production of radish pickle industry.