【作者】 李洁；

【导师】 柳陈坚；

【作者基本信息】 昆明理工大学 ， 生物工程（专业学位）， 2014， 硕士

【摘要】 豆豉在我国有着悠久历史,通常是以黑豆、黄豆为主要原料,利用人工添加或空气中特定的微生物附着发酵而成。云南地处中国低纬度西南高原地区,独特的地理环境及多样的饮食风俗造就其丰富的豆豉资源,其发酵微生物也呈现与众不同的多样性。研究发现,某些豆豉产地的传统发酵豆豉中乳酸菌作为优势菌种对豆豉发酵发挥重要作用。乳酸菌发酵产生多种抑菌物质,主要包括有机酸、细菌素、环二肽、短链脂肪酸等。有机酸作为乳酸菌发酵液的主要抑菌物质,其主要研究集中于分析与定量,与此同时利用化学合成的有机酸来模拟抑菌实验,而这些研究忽略各有机酸之间的相互作用以及有机酸与其他抑菌物质之间的相互协同作用。本研究将通过乳酸菌的抑菌活性及其发酵液中有机酸的组分分析,研究其抑菌活性与有机酸之间的相关性,主要研究成果如下:1.从云南省丘北、绿春、玉门、建水、石屏、个旧等地采集到多个豆豉样品,从中分离得到89株乳酸菌,包括18株Lactobacillus plantarum、8株Enterococcus faecium、8 株 Pediococcus acidilactici、9 株P.pentosaceus、8 株 Weissella paramesenteroides、4株Lb.fermentum、9株W.confusa、6 株 E.durans、5 株W.cibaria、3株 E.hirae、2 株 Lb.rhamnosus、5 株 Lactococcus lactis、4 株 Lb.brevis。2.采用spot-on-law方法及agar well diffusion方法对乳酸菌的抑菌活性进行分析发现,W.paramesenteroides、P.acidilactici及Lb.plantarum的抑菌活性较好,而各种菌间其抑菌活性同样存在较大差异。当改变乳酸菌的发酵碳源时,抑菌活性的强弱趋势为:葡萄糖>果糖>蔗糖>乳糖>淀粉。随着发酵时间延长,乳酸菌的pH、菌落数及抑菌比分别在20 h,15 h,42 h左右基本达到稳定。3.采用HPLC法测定乳酸菌发酵液中有机酸组分随发酵碳源及发酵时间的变化。当发酵碳源为葡萄糖时,有机酸种类最多且含量最高,随着发酵时间变化,各种有机酸含量也呈现不同的变化趋势。分析抑菌活性及有机酸含量的相关性发现,乳酸、乙酸与总酸含量与抑菌活性存在正相关性(P<0.05)。更多还原

【Abstract】 Fermented soybean has a long history in China,which was made from black bean and soybean and fermented by microbe that added or natural in the air.Yunnan province lies in the plateau regions of south-west of China.Because of the characteristic geographical environment and various of diet customs,Yunnan has rich resources of fermented soybean and all kinds of fermentation microorganism.Lactic acid bacteria is dominant strains and play an important role in fermented soybean in some manufactory regions.Lactic acid bacteria fermentation produced a variety of antimicrobial substances,including organic acid,bacteriocins,cyclic dipeptide,short chain fatty acids and so on.Organic acid is the main antimicrobial material of lactic acid bacteria fermention.The main research of organic acid focus on analysis and quantitative,and to simulate the antibacterial experiment using the chemical synthesis of organic acids at the same time,however wich ignores the interaction between organic acid and organic acid and the synergies between oganic caid and other antibacterial material.This study would study the correlation between antimicrobial activity and organic acid.The main research results are as follows:1.There were 89 lactic acid bacteria strains isolated from the traditional fermented douchi which were collected from Qiubei,Yimen,Jianshui,Shiping,Gejiu of Yunnan province.These strains were identified as Lb.plantarum(8 strains),E.faedum(8 strains),P.acidilactici(8 strains),P.pentosaceus(9 strains),W.paramesenteroides(8 strains),Lb.fermentum(4 strains),W.confusa 9 strains),E.durans(6 strains),W.cibaria(5 strains),E.hirae(3 strains),Lb.rhamnosus(2 strains),L.lactis(5 strains),Lb.brevis(4 strains)respcetely.2.Used spot-on-lawn and agar well diffusion methods to research antimicrobial activity and found that W.paramesenteroides,P.acidilactici,L.plantarum had higher antimicrobial activity.However it was showed very different in every strain.Changed the carbon source of culture medium,the antimicrobial activity trend was as follow:lactose>fructose>sucrose>glucose>starch.The pH,lactic acid bacteria colonies and inhibition ratio were stable in 20 h,15 h,and 42 h along with the extension of fermented time.3.The production of oganic acid along with fermented time and carbon source changed were analyzed by HPLC.The organic acid content and concentration was the highest when glucose was used as carbon source,and the content and concentration were changing along with time.Between the content of lactic acid,acetic acid,total acid concentration and antimicrobial activity was showed positive correlation(P<0.05).更多还原