本文關(guān)鍵詞：二氧化碳輔助超高壓對大腸桿菌和金黃色葡萄球菌的殺菌研究　出處：《中國農(nóng)業(yè)大學(xué)》2016年博士論文　論文類型：學(xué)位論文

  更多相關(guān)文章： 二氧化碳 超高壓 大腸桿菌 金黃色葡萄球菌 殺菌機(jī)制 自然菌群

【摘要】：本文以脫毒型食源性致病菌革蘭氏陰性菌(G-)大腸桿菌(Escherichia coli)和革蘭氏陽性菌(G+)金黃色葡萄球菌(Staphylococcus aureus)為目標(biāo)菌,研究二氧化碳(Carbon dioxide, CO2)輔助超高壓(High pressure processing, HPP)對E. coli和S. aureus的殺菌效果,并通過從細(xì)胞水平和分子水平分析了可能殺菌機(jī)制,最后將其應(yīng)用于黃瓜汁和蘋果汁自然菌群的殺滅。主要研究內(nèi)容如下：(1)不同因素對C02輔助HPP (CO2+HPP)處理E. coli和S. aureus的影響。真空頂空充入20%CO2對HPP有較強(qiáng)的輔助殺菌作用；兩種菌的穩(wěn)定期比對數(shù)期具有更強(qiáng)的抗性；與磷酸鹽緩沖液相比,黃瓜汁和蘋果汁體系對兩種菌有明顯的保護(hù)作用；HPP處理過程中C02溶解在菌液中最大濃度為0.7 mmol;(2) CO2+HPP對E. coli和S. aureus的殺菌動力學(xué)。CO2+HPP對E. coli和S. aureus的殺菌動力學(xué)曲線最適擬合模型為Biphasic,20% CO2與200 MPa/3 min、300 MPa/3min和400 MPa/3min輔助殺菌效果顯著；(3) CO2+HPP對E. coli和S. aureus細(xì)胞形態(tài)和結(jié)構(gòu)的影響。經(jīng)過CO2+HPP處理,細(xì)胞褶皺變形,細(xì)胞膜透性增強(qiáng),膜孔洞效應(yīng)明顯,內(nèi)容物大量流出,細(xì)胞質(zhì)產(chǎn)生空洞現(xiàn)象,呈均勻聚集狀態(tài),胞內(nèi)蛋白變性；顯著抑制E. coli胞內(nèi)亮氨酸芳基酰胺酶和萘酚-AS-BI-磷酸水解酶的活性,以及S. aureus胞內(nèi)α-葡萄糖苷酶的活性；(4) CO2+HPP對E. coli蛋白組的影響。E. coli經(jīng)HPP處理后有大量蛋白下調(diào)表達(dá),而經(jīng)CO2+HPP處理后差異下調(diào)蛋白明顯小于HPP處理樣品,可能是由于真空頂空充入C02帶來的酸逆境環(huán)境使細(xì)胞產(chǎn)生逆境相應(yīng),導(dǎo)致在大量蛋白上調(diào)表達(dá),在一定程度上掩蓋了由于CO2+HPP引起的蛋白下調(diào)；(5)從細(xì)胞水平和分子水平分析CO2+HPP可能的殺菌機(jī)制為：1)細(xì)胞水平。經(jīng)過CO2+HPP處理后,由于氣體在卸壓過程中的爆破效應(yīng)對細(xì)胞膜造成了嚴(yán)重?fù)p傷,細(xì)胞膜表面孔洞效應(yīng)明顯,細(xì)胞內(nèi)容物大量流失,嚴(yán)重影響了細(xì)胞正常的生理代謝；2)分子水平。經(jīng)過CO2+HPP處理后細(xì)胞能量代謝降低,胞內(nèi)碳氮不平衡,細(xì)胞正常的生理活動無法得到維持；轉(zhuǎn)錄與翻譯水平降低,蛋白合成代謝水平降低,遺傳物質(zhì)RNA和DNA的生成受到干擾；同時無法修復(fù)及重新合成受損的細(xì)胞膜,使膜主動運(yùn)輸能力減弱,胞內(nèi)大量內(nèi)容物流出;(6) 20% CO2+600 MPa/3 min處理黃瓜汁和蘋果汁中自然菌群(包括菌落總數(shù)、霉菌酵母和乳酸菌群)在22天4℃貯藏過程中呈現(xiàn)“S”型生長趨勢,可采用Logistic模型擬合；經(jīng)過20%CO2+600 MPa/3 min處理的黃瓜汁可實(shí)現(xiàn)15天的貯藏,蘋果汁在22天貯藏過程中均呈現(xiàn)微生物安全；貯藏過程中,20% CO2+HPP處理蘋果汁中果膠甲酯酶和多酚氧化酶殘存活性顯著降低,蘋果汁中的蔗糖轉(zhuǎn)化酶和黃瓜汁中的脂肪氧合酶保持較高水平；20% CO2+HPP處理有利于保持黃瓜汁和蘋果汁在貯藏過程中穩(wěn)定性、顏色和香氣物質(zhì)；經(jīng)過感官評價分析,經(jīng)CO2+600 MPa/3 min處理的黃瓜汁在4℃貯藏7天后、蘋果汁貯藏15天后的感官評價結(jié)果與未處理沒有顯著差異,依然可以被消費(fèi)者接受。
[Abstract]:This type of food borne pathogens and detoxification of gram negative bacteria (G-) in Escherichia coli (Escherichia coli) and gram positive bacteria (G+) Staphylococcus aureus (Staphylococcus aureus) as target bacteria, study on carbon dioxide (Carbon dioxide, CO2 (High pressure) auxiliary ultra high pressure processing, HPP) and S. coli E. on bactericidal effect aureus, and from the cellular level and molecular level analyses the sterilization mechanism, finally applied to cucumber juice and Apple Juice natural bacteria killing. The main contents are as follows: (1) different factors on C02 assisted HPP (CO2+HPP) E. coli and S. aureus of the vacuum headspace filled with 20%CO2. Have strong bactericidal effect on HPP; stability of two kinds of bacteria has stronger resistance than the logarithmic phase; compared with phosphate buffer, cucumber juice and Apple Juice system has markedly protective effect on two bacteria; HPP C02 dissolution process in suspension concentration is 0.7 mmol; (2) killing curves on E. CO2+HPP.CO2+HPP bactericidal kinetics of coli and S. aureus of E. coli and S. aureus the best fitting model for the Biphasic, 20% CO2 and 200 MPa/3 min, 300 MPa/3min and 400 MPa/3min (auxiliary bactericidal effect; 3) the effect of CO2+HPP on E. coli and S. aureus cell morphology and structure. After CO2+HPP treatment, cell fold deformation, cell membrane permeability increased, membrane pore effect, the contents of a large outflow, cytoplasmic voids phenomenon, homogeneous aggregation state, intracellular protein denaturation; E. coli significantly inhibited the intracellular leucine Fang arylamidase and naphthol -AS-BI- phosphate hydrolase activity, and the activity of S. aureus intracellular alpha glucosidase; (4) the influence of CO2+HPP on E. coli protein.E. coli group treated by HPP has a large number of proteins down regulated by CO2+H, and The protein was less than that of HPP treated sample differences down after PP treatment may be due to vacuum headspace filling C02 caused by acid stress causes cells to produce the corresponding stress, resulted in a large amount of protein increased to a certain extent masked due to CO2+HPP protein expression; (5) from cell and molecular level analysis of the sterilization mechanism of CO2+HPP may: 1) the level of cells. After CO2+HPP treatment, because the gas caused serious damage in pressure relief blasting effect in the process of cell membrane, the pores on the surface of the cell membrane effect is obvious, the cell content loss, serious impact on cell metabolism; 2) molecular level after treatment with CO2+HPP cells. The decline of energy metabolism, intracellular carbon and nitrogen balance, the normal physiological activities of cells can not be maintained; reduce the level of transcription and translation, protein synthesis and metabolism level is reduced, and the genetic material RNA The formation of DNA interference; at the same time to repair and re synthesis of the cell membrane is damaged, weakened the membrane active transport ability, the intracellular content of logistics; (6) 20% CO2+600 MPa/3 min natural flora Apple Juice juice and cucumber (including the total number of colonies, mold, yeast and lactic acid bacteria) showed "S" type the growth trend in 22 days at a temperature of 4 DEG C during storage, can be fitted by Logistic model; after 20%CO2+600 MPa/3 min treated cucumber juice can achieve 15 days of storage, Apple Juice showed microbial safety in 22 days during storage; during storage, 20% CO2+HPP Apple Juice in pectin residual activity significantly, Apple Juice in conversion of sucrose fatty enzyme and oxygen synthase in cucumber juice to maintain a higher level; 20% CO2+HPP treatment is conducive to maintaining stability and Apple Juice cucumber juice during storage, color and fragrance Gas substances; after sensory evaluation and analysis, the sensory evaluation results of cucumber juice processed by CO2+600 MPa/3 min after 4 days storage for 7 days and apple juice storage for 15 days had no significant difference from that of untreated, and could still be accepted by consumers.

【學(xué)位授予單位】：中國農(nóng)業(yè)大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TS201.3
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本文編號：1400518