【摘要】：近紅外光譜檢測技術是近年來發(fā)展最快的檢測技術之一,具有無損、快速、高效、方便而環(huán)保的特點。本文以處于對數生長期的大腸桿菌和單增李斯特菌等致病菌為研究對象,考察了近紅外光對致病菌細胞的作用機理,分析了近紅外光譜分析技術的光譜預處理方法,利用基于主成分分析技術的投影判別分析對致病菌的鑒別進行了研究,得到了預期結果。 1.采用光電比濁法和平板計數法,對大腸桿菌的對數生長期進行了研究。通過比較大腸桿菌的生長曲線圖,研究其生長趨勢,確定了大腸桿菌的對數生長期,最后選定14h為大腸桿菌培養(yǎng)時間。 2.通過單因素試驗和正交試驗,對大腸桿菌細胞破碎參數進行了研究。以大腸桿菌細胞破碎率為指標,研究了大腸桿菌細胞破碎參數,確定最佳破碎參數組合為:破碎功率400W、每次破碎5s、間隔5s、實際破碎總時間50min。 3.根據不同濃度梯度的大腸桿菌細胞壁和細胞質的近紅外光譜,分別考察了矢量歸一法、多元散射校正法、一階導數法、一階導數+矢量歸一法等近紅外分析技術的光譜預處理技術,結果表明,一階導數法和一階導數+矢量歸一法進行光譜預處理的效果很不理想,而采用矢量歸一法和多元校正法進行光譜預處理可得到滿意的效果。 4.利用基于主成分分析技術的投影判別分析,研究了近紅外光對大腸桿菌細胞壁和細胞質的作用情況,結果表明,致病菌濃度對近紅外光的吸收并不成濃度比例關系,而細胞壁和細胞質對近紅外光的吸收則明顯有所不同,即利用其近紅外吸收光譜可以區(qū)分二者。 5.采用基于主成分分析技術的投影判別分析,不論是利用細胞壁或者是細胞質的近紅外光譜,都可以將大腸桿菌和單增李斯特氏菌區(qū)分開來,但采用細胞壁的近紅外光譜來區(qū)分兩種致病菌,準確度更高。
[Abstract]:Near infrared spectroscopy (NIR) is one of the fastest developing detection techniques in recent years. It has the characteristics of nondestructive, rapid, efficient, convenient and environmentally friendly. In this paper, the action mechanism of near-infrared light on pathogenic bacteria such as Escherichia coli and Listeria monocytogenes in logarithmic growth period was investigated, and the spectral pretreatment method of near-infrared spectroscopy was analyzed. The identification of pathogenic bacteria was studied by projection discriminant analysis based on principal component analysis (PCA), and the expected results were obtained. 1. The logarithmic growth period of Escherichia coli was studied by photoelectric turbidimetry and plate counting. By comparing the growth curve of Enterobacter coli, the growth trend of E. coli was studied, and the logarithmic growth period of E. coli was determined. Finally, 14 h was selected as the culture time of E. coli. 2. The breaking parameters of E. coli cells were studied by single factor test and orthogonal test. Taking the breaking rate of E. coli cells as an index, the breaking parameters of E. coli cells were studied. The optimum breaking parameters were determined as follows: crushing power 400W, breaking power 5s, interval 5s, actual total breaking time 50min. 3. According to the near infrared spectra of the cell wall and cytoplasm of Escherichia coli with different concentration gradient, vector normalization method, multiple scattering correction method and first order derivative method were investigated, respectively. The results show that the first derivative vector normalization method and the first derivative vector normalization method are not ideal for the spectral pretreatment of near infrared analysis techniques, such as the first derivative vector normalization method and the first derivative vector normalization method, and the results show that the first derivative vector normalization method and the first derivative vector normalization method are not ideal. The method of vector normalization and multi-element correction can be used to pre-process the spectrum, and the results are satisfactory. 4. The effects of near infrared light on the cell wall and cytoplasm of Escherichia coli were studied by projection discriminant analysis based on principal component analysis. The results showed that the concentration of pathogenic bacteria did not proportional to the absorption of near infrared light. The absorption of near-infrared light by cell wall and cytoplasm is obviously different, that is to say, the near-infrared absorption spectra can be used to distinguish the two. 5. The projection discriminant analysis based on principal component analysis can distinguish Escherichia coli and Listeria monocytogenes from Listeria monocytogenes by using cell wall or near infrared spectrum of cytoplasm. But using the near infrared spectrum of cell wall to distinguish the two pathogens, the accuracy is higher.
【學位授予單位】：河南科技大學
【學位級別】：碩士
【學位授予年份】：2009
【分類號】：R378

【引證文獻】

相關碩士學位論文 前1條

1 張雅琪;基于傅里葉變換近紅外光譜法的食源性致病菌的鑒別研究[D];河南科技大學;2011年

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本文編號：2436629