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从腐烂的猕猴桃中初筛醋酸菌,于不同浓度乙醇的液体培养基、不同温度下驯化,得到一株在高温、高醇条件下产酸量较高的菌株WT08。该菌株在含6%(体积分数,下同)乙醇的培养基中32℃培养72 h,产酸量达39.09 g/L;在含12%乙醇的培养基中32℃培养72 h,产酸量为12.99 g/L;在产酸基础培养基中,40℃培养72 h,产酸量达到5.89 g/L。对该菌株进行形态学观察、生理生化及分子生物学鉴定,初步确定该菌株为巴氏醋杆菌。利用能量为10 keV,剂量为70×2.6×10~(13)ions/cm~2的低能N~+注入WT08菌株,在后代中选育得到耐醇、耐高温性能都提高的菌株WT08-18,该菌株最高产酸达49.86 g/L,在含12%乙醇的培养基中产酸达15.16 g/L;在基础培养基中40℃培养72 h,产酸量达10.96 g/L,且该菌株有良好的遗传稳定性。将WT08-18菌株液体扩大培养,以体积分数3%的接种量接入成熟醋醅中,按照传统酿制工艺酿造,醋酸产量比传统酿制的提高30.54%,酒精转酸率提高18.81%,具有广泛的应用前景。 相似文献
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该研究旨在提高一株环境分离菌株的产酶效率,为后续菌株及其蛋白酶的应用提供前期实验基础。通过水解圈法初步检测菌株S8的产蛋白酶能力,并通过16S rRNA序列比对确认其为波茨坦短芽孢杆菌。通过单因素试验确定了最佳培养条件和培养基添加成分。并采用Plackett-Burman设计和最陡爬坡试验对培养条件和培养基进行响应面优化。优化结果显示,在发酵时间为38.70 h、菌液接种量为1.84%(V/V)、发酵温度为35 ℃、酵母粉添加量为23.70 g/L、胰蛋白胨添加量为11.70 g/L、MgSO4添加量为20.20 g/L的条件下,菌株的产酶活力可达到114.79 U/mL,相比优化前提升了209.70%。研究结果为该菌株的后续发酵应用提供了科学数据。 相似文献
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鲐鱼中产组胺菌的分离筛选与生物学特性初步研究 总被引:1,自引:0,他引:1
利用产组胺菌鉴别培养基,对鲐鱼内脏中产组胺菌进行初步筛选,结合高效液相色谱分析方法对分离菌株的产组胺能力进行了确认;并通过菌株的生理生化、形态和16SrDNA基因序列分析对分离得到的菌株进行鉴定;研究了温度和pH对菌株生长和产组胺的影响。结果表明,从鲐鱼中初步分离的4株菌(T4、T5、T6和T9)在组胺发酵培养基中能够产生164.1~466.1μg/100mL组胺;经生理生化特性及16SrDNA序列测定为相同菌种,对其中T4菌株进行进化树分析,发现菌株T4与产粘液变形杆菌相似性最高。T4菌株生长和产组胺的最适温度均为20℃,最适pH均为7。 相似文献
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5’-AMP脱氨酶能够不可逆的将腺苷酸转变为肌苷酸,在医疗保健、调味品等领域中应用十分广泛.该研究通过豆腐的自然发酵制备腐乳半成品,并分别以PDA、YPD和MRS培养基进行腐乳中微生物纯化,获得单一菌株36株.通过进一步的摇瓶发酵培养,检测到具有5’-AMP脱氨酶活性的为18株.选取活性最高(编号为DFP-102)的菌株进行菌落形态分析,初步鉴定该菌株为毛霉菌属.通过培养基发酵条件优化,确定该菌株产酶的适宜发酵条件为培养基pH值为6.0,培养温度24℃,接种量为5%,发酵48h.在最佳产酶条件下,5’-AMP脱氨酶活性可达472.3U/mL. 相似文献
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益生菌是对人体健康具有促进作用的活性微生物,具有食用安全性。从酸乳制品中筛选出一株具有产γ-氨基丁酸能力较高的菌株,经形态学观察、生理生化检验和16S r DNA序列分析,初步鉴定为短乳杆菌(Lactobacillus brevis),属益生菌范畴。经培养基和发酵条件优化,发酵液中γ-氨基丁酸的含量可达2.03 g/L。以该菌株为出发菌株进行紫外诱变处理,得到一株突变菌株,γ-氨基丁酸产量达2.31 g/L,与出发菌株相比提高了11.4%。经过多次传代,稳定性较好。研究结果有助于拓宽益生菌产品应用领域。 相似文献
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为了研究一种利用植物乳杆菌发酵的由紫甘蓝、胡萝卜和西红柿混合的饮品。文章确定了由紫甘蓝、胡萝卜和西红柿按照6∶3∶1的比例配制的蔬菜汁,以此为培养基,利用植物乳杆菌发酵产酸。并在单因素实验的基础上,以总酸为指标,利用响应面法对接种量、温度和时间进行发酵优化实验。结果表明,植物乳杆菌在接种量为4.2%,温度为36℃,发酵时间为77 h时达到最佳条件。在该条件下进行验证实验,得到产酸总量为11.238 g/L,与模型预测值11.242 g/L接近,可用于预测植物乳杆菌的发酵条件,为进一步制备饮品提供了依据。 相似文献
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紫米在储藏过程中易受内部及外部因素如温度、湿度、氧气等的影响,合适的包装能有效抑制紫米的陈化与霉变,本研究通过使用四种不同阻隔性的包装材料AL/PE、PA/PE单面压纹、PA/PE、PE/EVOH/PA/PE对紫米进行包装后储藏98 d,储藏期间定期测定紫米的水分含量、脂肪酸值、蛋白质含量、霉菌数量、电导率、色价、色差、电子鼻气味、形态结构等指标的动态变化并对各指标进行相关性分析。结果表明,各材料包装的紫米的水分含量有不同程度的上升而后下降、电导率先增加后降低、△E、脂肪酸值不断增大,蛋白质含量小幅上升后不断下降,霉菌含量先增加后减少至稳定,电子鼻能明显区分不同储藏期及不同包装材料中的紫米。从水分含量、△E、色价、脂肪酸值、形态结构指标来看,高阻隔材料PE/EVOH/PA/PE包装的紫米品质较稳定,从霉菌含量、电导率指标来看,PA/PE单面压纹材料包装的紫米品质较稳定。 相似文献
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以紫色马铃薯为原料,对丙烯酰胺含量低,色素保留较好的紫色马铃薯薯条生产工艺进行研究,得到最佳工艺为烫漂处理+微波真空冷冻。烫漂处理中最优护色剂组合为L-半胱氨酸浓度0.08%、柠檬酸浓度0.1%、氯化钙浓度125×10-6g/mL,浸泡时间10min;最佳烫漂温度70℃;烫漂时间5min。该工艺成品中未检出丙烯酰胺,色泽(E值)可降低到92.8739±5.3234。 相似文献
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The in vitro role of Lactobacillus acidophilus was investigated to explore the potential to inhibit coliforms. A threefold concentrated cell-free extract from L. acidophilus SBT2074 could efficiently inhibit most of the tested Gram-positive and Gram-negative bacteria. Among the three strains of L. acidophilus, SBT2062, SBT2071, and SBT2074, only L. acidophilus SBT2074 showed this inhibitory property. These three strains were also tested in coculture with Escherichia coli 3544 in skim milk medium. The fermentation could result in complete inhibition of E. coli in 36 h. Short-term administration of L. acidophilus SBT2074 in rats with and without E. coli resulted in significant inhibition of coliforms and anaerobes. The E. coli infected rats regained the normal flora in the presence of lactic acid bacteria. The fecal enzyme beta-glucuronidase activity was also decreased significantly when L. acidophilus SBT2074 was administered and was related to the decreased number of bacteria in the intestinal tract. The analysis of the small intestinal contents showed that the concentrations of coliforms in the duodenum, jejunum, and the ileum were significantly reduced by the administration of lactic acid bacteria. The effects are seen in a short period, suggesting that L. acidophilus SBT2074 fermentate may have clinical application for people suffering from gastrointestinal distress caused by coliforms. 相似文献
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玉米紫色植株色素理化性质研究 总被引:1,自引:0,他引:1
研究了从玉米紫色植株中提取出色素的理化性质。结果表明:玉米紫色植株色素为水溶性物质,在酸性结介子中呈稳定的红色,可见光区域最大吸收波长为515nm,对光、氧化剂、还原剂、抗坏血酸、Fe3 和Sn2 等敏感,对热、苯甲酸钠、葡萄糖、果糖和果葡糖浆等有较好的稳定性。 相似文献
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优化了超声波辅助提取紫马铃薯(黑金刚)花色苷的工艺条件,并在此基础上研究了紫马铃薯花色苷的纯化工艺及其在不同环境条件下的稳定性。结果表明,最佳提取条件为:提取功率300 W,料液比1:50 g/mL,提取温度50 ℃,提取时间15 min,在此条件下提取量为(1.435±0.27) mg/g。采用AB-8大孔树脂,上样浓度0.29 mg/mL,纯化样品量9 BV,用6 BV 60%乙醇溶液洗脱,上样和洗脱速度均为2.0 mL/min,纯化后提取液中花色苷的浓度达到(6.43±0.37) mg/mL。稳定性研究结果表明,紫马铃薯花色苷在245 nm短波紫外线和室内散射光条件下稳定性较差,在黑暗避光条件下稳定;加热条件下稳定性随温度升高而降低;在含有Al3+、Mg2+、K+、Ca2+、Na+、Zn2+离子的溶液中稳定,在含有Cu2+的溶液中产生沉淀;在酸性环境中稳定,在碱性环境中易降解。因此,紫马铃薯花色苷应尽量在避光,冷藏或常温的酸性环境下贮藏和使用。优化的紫马铃薯花色苷提取工艺合理且具有良好的可行性,提取出的紫马铃薯花色苷产物具有较高的稳定性,可作为健康食品着色剂或食品功能性成分应用于食品的生产和研发过程中。 相似文献
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ABSTRACT: The association of powdered infant formula with cases of severe Enterobacter sakazakii infections in immunocompromised and premature neonates has led to a need to learn about the basic behavior of this emerging pathogen in food systems and the environment. The current study examines the microorganism's stationary-phase acid resistance using 12 strains that had been previously used to characterize its thermal resistance. Acid resistance was determined by initially culturing the isolates for 18 h in brain heart infusion broth (BHI) at 36 °C, transferring the cells to tryptic soy broth (TSB) adjusted to pH 3.0 and 3.5, and determining E. sakazakii survival over the course of 5 h incubation at 36 °C. At pH 3.5, 10 of the 12 strains showed less than a 1 log cycle decline over the 5-h incubation period, with the most acid sensitive strain showing an approximate 3.5 log cycle decline. At pH 3.0, the decline over the 5-h incubation period ranged from 4.9 to >6.3 log cycles; however, substantial diversity was evident when the 1-h/pH 3.0 results were compared. The effect of habituating the cells to a moderately acidic environment was determined by growing the strains in TSB with 0% (nonacidogenic) and 1% glucose (acidogenic), transferring the cells to acidified (pH 3.0) BHI, and determining E. sakazakii survival over the course of 5 h of incubation at 36 °C. While there was diversity observed among the strains, in general the stationary-phase acid resistances of several of the strains were enhanced, at least transitorily, by growth in the acidogenic medium. No apparent correlation between the stationary-phase relative acid resistances of the strains based on the 1-h/pH 3.0 acid inactivation values and the previously reported thermal D-values was observed. 相似文献