摘要
【目的】研究鼠李糖乳杆菌发酵甘薯淀粉加工废渣生产乳酸的工艺条件,为薯渣的治理和利用提供新的技术思路。【方法】使用元素分析仪对甘薯淀粉废渣中的主要元素进行分析测定,同时,在以菌体OD值法确定的鼠李糖乳杆菌的生长对数期内分别取不同时间点设置4组乳酸发酵试验,以该菌利用葡萄糖液体培养基产乳酸的发酵效率为考察指标确定该菌的乳酸发酵最适种龄。在此基础上,利用鼠李糖乳杆菌对甘薯废渣直接进行固体发酵:采用单因素试验方法分别考察接种量、发酵温度、碳酸钙添加量,以及外加氮源对乳酸发酵效率的影响;此外,考察外加氮源对发酵结束后薯渣固体发酵醪中的生物量的影响;结合正交试验设计,得到影响薯渣发酵产乳酸因素的最优组合。【结果】元素分析结果显示甘薯淀粉废渣是一种高C、H含量的生物质,其干渣中C、H元素质量百分含量分别达40.34%、6.16%,而N元素质量百分含量仅为0.32%,虽C元素含量丰富,但N元素相对匮乏,需要外加氮源方可进一步促进其生长代谢。通过菌体OD值法确定的鼠李糖乳杆菌的生长曲线显示,菌体接入2 h后OD值迅速增长,菌体生长进入对数期。8 h后OD值基本不变,菌体进入稳定期。确定了种子的对数生长期在2—8 h。在该时间区间内以4 h龄种子的乳酸发酵效率最高,达92.39%,对应残糖浓度最低,为0.59 g·L^(-1),确定4 h是鼠李糖乳杆菌乳酸发酵的最适种龄。薯渣固体发酵中分批单因素试验结果依次为:接种量在10%时发酵效率达最高,为83.87%;发酵温度在37℃时发酵效率最高,达85.55%;Ca CO_3添加量在5%时发酵效率达最大值,为90.24%;4种无机氮源中尿素组发酵效率达91.01%;尿素在0.8%添加量下发酵效率最大值为94.13%,同时发酵醪中活菌数达4.32×10~8 cfu/g。依据以上单因素试验结果,Ca CO_3适宜添加量为5%,与中和发酵体系中初始糖(10
Lactic acid fermentation process by Lactobacillus rhamnosus using sweet potato residue was studied in this paper in order to provide new technical strategy for utilization of sweet potato dregs. [Method] Firstly, the major elements of sweet potato starch residue were measured by elemental analyzer, meanwhile, there were four fermentation groups carried out with four different time points during the logarithmic growth phase of L. rhamnosus which was identified through OD value of bacteria, the optimal seed age was confirmed taking the fermentation efficiency of lactic acid production using liquid glucose culture as index of investigation. Then on this basis, the sweet potato dregs were used by L. rhamnosus through solid state fermentation （SSF） in the following research： firstly, the effects of inoculation amount, temperature, CaCO3 quantity, nitrogen sources on lactic acid production were investigated through single factor experiments. In addition, the effects of nitrogen sources on viable bacteria counts in fermenting mash after fermentation were studied also. Then the optimal combination was established by further orthogonal design. [ Result] Element analysis results showed that sweet potato starch residue was full of C and H, with weight percentage content of 40.34% and 6.16%, respectively. The content of N was only 0.32%. Although C was quite rich in sweet potato starch residue, N was deficient comparatively, it was necessary to add N source to promote growth and metabolism of L. rhamnosus furthermore. The growth curve ofL. rhamnosus identified by OD value showed that the OD value ofL. rhamnosus increased rapidly after inoculated for 2 h, which means that the logarithmic growth phase began. The OD value wasn＇t change approximately after 8 h, which means that the stationary growth stage began. It was confirmed that the logarithmic growth phase of L. rhamnosus was 2 h to 8 h. The fermentation efficiency was the highest, reached 92.39%, when the seed age got to 4 h, and the content of residual glucose w
出处
《中国农业科学》
CAS
CSCD
北大核心
2016年第9期1767-1777,共11页
Scientia Agricultura Sinica
基金
国家现代农业产业技术体系建设专项(CARS-11-B-17)
中国科学院环境与应用微生物重点实验室/环境微生物四川省重点实验室开放研究基金(Y1D5031101)
关键词
鼠李糖乳杆菌
甘薯渣
发酵
乳酸
Lactobacillus rhamnosus
sweet potato residue
fermentation
lactic acid
