乳酸菌复合系和植物乳杆菌提高柳枝稷青贮效果

该文旨在探讨接种乳酸菌复合系SGL和植物乳杆菌（Lactobacillus plantarum）对柳枝稷青贮效果的影响。以营养生长阶段的柳枝稷为原料,分别接种1 OD600/kg 鲜质量的SGL和Lactobacillus Plantarum,以不接菌的处理作为对照。在发酵第3、10、20和30天开罐取样进行检测分析发酵饲料品质,通过短期人工瘤胃技术测定体外瘤胃发酵参数的变化,并运用高通量测序技术分析原料和青贮料的细菌多样性。结果表明：接种乳酸菌复合系SGL和Lactobacillus Plantarum均能有效抑制Enterobacter和Clostridium,使Lactobacillus成为控制发酵的优势菌,加快青贮过程中pH值的下降速率,提高柳枝稷青贮饲料品质,并提高柳枝稷青贮料的瘤胃发酵效果,复合菌系SGL比纯培养的Lactobacillus Plantarum的效果更突出。     

自然发酵和接种发酵方法对白菜品质的影响(简报)

以自然发酵和人工接种发酵(Lactobacillus pentosus 和 Leuconostoc.mesenteroides 为发酵剂)加工的白菜为材料,对比了两种加工白菜亚硝酸盐含量随时间的变化以及有益微生物(乳酸菌)和有害微生物数量的变化,并对其制品做了感观分析.结果得出人工接种发酵白菜中亚硝酸盐含量在发酵整个过程均比自然发酵的低,且未出现自然发酵白菜初期出现的"亚硝峰"; 人工接种发酵白菜中肠杆菌及乳酸菌之外的需氧嗜温菌的数量较自然发酵的少;乳酸菌数量较自然发酵的多;人工接种发酵白菜感官分析优于自然发酵.说明人工接种发酵白菜的品质优于自然发酵加工的制品.     

同/异型乳酸菌对青贮玉米开窖后品质及微生物的影响

该研究旨在分析添加不同发酵类型的乳酸菌处理对开窖后玉米（Zea mays L.）青贮发酵品质、微生物数量及有氧稳定性的影响,为生产实践提供参考。设计4个添加乳酸菌玉米青贮处理：CK处理（不加任何菌剂）;T处理（同型发酵乳酸菌）：Lactobacillus plantarum和Pediococcus acidilactici复合添加,添加量为1∶1,1×105 cfu/g;Y处理（异型发酵乳酸菌）：Lactobacillus buchneri,添加量为1×105 cfu/g;TY处理（同型+异型发酵乳酸菌）：Lactobacillus plantarum、Pediococcus acidilactici和Lactobacillus buchneri复合添加,添加量为1∶1∶1,1×105 cfu/g。发酵期为60 d,检测开窖后各处理第0、48、96、144、192、240 h发酵品质及微生物的变化,应用隶属函数法对玉米青贮发酵品质及微生物数量进行综合评判。结果表明Y和TY处理的有氧稳定时间显著高于其余处理（63.87～64.67 h,P<0.05）,分别达到195.58和196.21 h,且乙酸质量分数始终显著高于CK和T处理（P<0.05）。T处理pH值始终显著低于其余处理（P<0.05）,且乳酸质量分数始终显著高于CK和Y处理（P<0.05）。Y处理WSC（water soluble carbohydrate）质量分数始终显著高于其余处理（P<0.05）,霉菌数量始终显著低于其余处理（P<0.05）。CK处理的NH3-N质量分数,好氧细菌数量及CO2产量始终显著高于其余处理（P<0.05）。开窖时间与各处理的CO2产量、乳酸菌和酵母菌数量分别满足Allometric1,ExpDec1和Logistic非线性关系,与霉菌和好氧细菌数量呈一元线性关系。综合评价排序：Y处理>TY处理>T处理>CK处理。因此,单一添加异型发酵乳酸菌的玉米青贮,开窖后在改善发酵品质、降低有害微生物数量、提高有氧稳定性方面均优于单一添加同型或复合添加乳酸菌的玉米青贮。     

Effect of nitrite accumulation on nitrous oxide emission and total nitrogen loss during swine manure composting

The present study investigated the nitrogen balance in swine manure composting to evaluate the effect of nitrite (     ) accumulation, which induces nitrogenous emissions, such as N₂O, during compost maturation. During active composting, most N losses result from NH₃ emission, which was 9.5% of the initial total nitrogen (TN_initial), after which,     began to accumulate as only ammonia-oxidizing bacteria proliferated. After active composting, the addition of mature swine compost (MSC), including nitrite-oxidizing bacteria (NOB), could prevent     accumulation and reduce N₂O emission by 70% compared with the control in which     accumulated as a result of delayed growth of indigenous NOB. Total N₂O emissions in the control and in the treatment of MSC addition (MA) were 9.3% and 3.0% of TN_initial, respectively, whereas N losses as the sum total of NH₃ and N₂O over the whole period were 19.0% (control) and 12.8% (MA) of TN_initial, respectively. However, the difference in total N losses was markedly greater than that measured as NH₃ and N₂O, which were 27.8% (control) and 13.3% (MA) of TN_initial, respectively. These results demonstrated that the magnitude of nitrogen losses induced by     accumulation is too large to ignore in the composting of swine manure.     

产脂肪酶乳酸菌对羊肉发酵香肠脂肪酸的影响

脂肪酶在肉制品加工中会影响风味物质的积累与产生,发酵肉制品生产中常通过添加产脂肪酶菌株来改善制品的风味。通过乳酸菌在代谢过程中分解三丁酸甘油酯产生透明圈的大小,判断菌株产脂肪酶的活力,同时结合脂肪酶基因Lip0069、Lip0893表达量的变化情况,筛选产脂肪酶能力较高的乳酸菌,研究该菌株对发酵香肠中脂肪酸的影响。结果表明,瑞士乳杆菌TR1-1-3代谢过程中产酶活力最强,编码脂肪酶的基因Lip0069、Lip0893表达量最高。发酵香肠试验组共检测到34种脂肪酸,其中饱和脂肪酸（Saturated Fatty Acids, SFA）16种、单不饱和脂肪酸酸（Monounsaturated Fatty Acids, MUFA）9种和多不饱和脂肪酸（Polyunsaturated FattyAcids, PUFA）9种。含量较高的MUFA主要是油酸（C18:1C9）、棕榈油酸（C16:1）、十七碳烯酸（C17:1）、肉豆蔻烯酸（C14:1）。含量较高的PUFA主要是亚油酸（C18:2C9）、亚麻酸（C18:3N6、C18:3N3）、花生四烯酸（C20:4）、二十二碳六烯酸（C22:6,Docosahexaenoic Acid,DHA）。TR1-1-3和ZF22组发酵2 d后,MUFA的含量明显上升（P<0.05）。12 d时5个试验组MUFA的含量均达到最高,其中TR1-1-3增长比例最高,且与ZR、M组差异显著（P<0.05）。TR1-1-3组发酵2 d后PUFA的含量发生了明显的变化（P<0.05）,12 d时TR1-1-3组 PUFA的含量增长了54.17%,且与其他试验组相比差异显著（P<0.05）。乳酸菌TR1-1-3可降低产品中SFA在脂肪酸中所占比例,明显加快MUFA、PUFA的增加速度及其含量,可为研究改善香肠脂肪特性提供良好的前景。     

Gas-liquid chromatographic determination of nitrate and nitrite in cheese, ham, fish sausage, cod roes, and salmon roes

The 2,4-xylenol method was modified and a gas-liquid chromatographic (GLC) method was developed for nitrate and nitrite determinations in several foods. Either a flame ionization (FID) or an electron capture detector (ECD) can be used. Proteins and fats are removed from warm alkaline water with zinc sulfate and filtered. The filtrate is evaporated to dryness, redissolved in water, and reacted with 2,4-xylenol in the presence of sulfuric acid to form 6-nitro-2,4-xylenol. Interfering chlorides are precipitated with silver sulfate and the nitrosylenol is extracted with hexane, concentrated, and injected. Nitrite in the filtrate is distilled at pH 5, collected in alkaline solution, and dried. The residue is oxidized to nitrate with permanganate in the presence of sulfuric acid, and then chromatographed in the same manner as nitrate. Recoveries from several foods were 83--100% for nitrate and 80--100% for nitrite. The limit of sensitivity was 0.1 ppm for both residues.     

高效纤维素优势分解菌的筛选和鉴定

本试验基于获得高效纤维素优势分解菌的目的,通过分离纯化初步得到30株菌株,利用刚果红染色法初筛共得到14株纤维素分解菌,并通过滤纸条崩解实验进一步进行筛选得到5株效果较好的纤维素分解菌,通过发酵产酶利用DNS显色法测定CMC酶活力和FPA酶活力最终确定了4株优势纤维素分解菌,通过测定4株菌株的羧甲基纤维素酶(CMCase)、滤纸酶(FPA)以及β-葡萄糖苷酶(β-Gase)活,验证4株纤维素优势分解菌的产酶能力,并分别命名为X-1、X-6、X-7和X-11,并将该4株优势纤维素分解菌应用于秸秆的液态发酵,其对秸秆的降解率较自然降解相比,降解率分别提高了31.92%、40.15%、35.29%和39.98%。对4株优势菌株进行了分子鉴定,根据16S r DNA序列比对结果表明,菌株X-1、X-7和X-11均为粪产碱杆菌;菌株X-6属于解糖假苍白杆菌。     

石灰性土壤中解磷优势菌的筛选研究

从石灰性土壤作物根际土样筛选出2株具有较强解P能力的优势菌株“B2”和“B67”,平板培养溶P圈D/d值分别为5.1和3·8,液体摇床培养过程中产生苹果酸、丙二酸、草酸和乳酸等多种有机酸,产酸总量分别为对照的28·25和19.78倍,pH分别较对照下降2.3和1.1,将“B2”和“B67”的培养液分别接种到4个不同地区土壤中恒温恒湿培养20d后测定结果表明,所有土壤中速效磷含量均有所提高,且接种“B2”处理分别为对照的2.64、3.04、1.71和2.20倍,接种“B67”处理分别为对照的2.12、1.90、1.35和1.78倍,且发现其溶P效果和土壤磷酸酶活性与有效活菌数变化趋势基本一致。     

基于电子舌的鱼肉品质及新鲜度评价

为了能用仪器快速客观地评价鱼肉的品质和新鲜度,利用该课题组开发的多频脉冲电子舌,对鲈鱼、鳙鱼、鲫鱼3种淡水鱼和马鲇鱼、小黄鱼、鲳鱼3种海水鱼进行了评价试验。淡水鱼宰杀后置于4℃下冷藏,冰冻海水鱼在室温下解冻后再置于4℃下冷藏。每天每一鱼取5份肉样进行电子舌检测。结果表明:鱼在不同时间点的品质特性可以用电子舌加以有效区分,据此可以较准确地表征鱼类新鲜度的变化;电子舌不仅可以有效区分淡水鱼和海水鱼,而且还可以辨识不同品种淡水鱼或海水鱼之间的差异。电子舌作为一种新型的现代化智能感官仪器,在鱼肉的品质以及新鲜度评价中具有巨大潜力。     

Effect of nitrite accumulation on nitrous oxide emission and total nitrogen loss during swine manure composting

Abstract

The present study investigated the nitrogen balance in swine manure composting to evaluate the effect of nitrite (NO^? ₂) accumulation, which induces nitrogenous emissions, such as N₂O, during compost maturation. During active composting, most N losses result from NH₃ emission, which was 9.5% of the initial total nitrogen (TN_initial), after which, NO^? ₂ began to accumulate as only ammonia-oxidizing bacteria proliferated. After active composting, the addition of mature swine compost (MSC), including nitrite-oxidizing bacteria (NOB), could prevent NO^? ₂ accumulation and reduce N₂O emission by 70% compared with the control in which NO^? ₂ accumulated as a result of delayed growth of indigenous NOB. Total N₂O emissions in the control and in the treatment of MSC addition (MA) were 9.3% and 3.0% of TN_initial, respectively, whereas N losses as the sum total of NH₃ and N₂O over the whole period were 19.0% (control) and 12.8% (MA) of TN_initial, respectively. However, the difference in total N losses was markedly greater than that measured as NH₃ and N₂O, which were 27.8% (control) and 13.3% (MA) of TN_initial, respectively. These results demonstrated that the magnitude of nitrogen losses induced by NO^? ₂ accumulation is too large to ignore in the composting of swine manure.