秸秆厌氧干发酵产沼气的研究

本试验以玉米秸、稻草、烟叶杆、木薯杆为代表的秸秆作为原料,在温度38℃,采用批量发酵工艺进行高浓度厌氧发酵产气研究。试验结果表明,玉米秸、稻草、烟叶杆及木薯杆的TS产气率分别为413ml／g、33ml／g、333ml／g、222ml／g,而VS产气率分别为470ml／g、387ml／g、426ml／g、24ml／g。     

高通量测序分析玉米秸秆与牛粪联合发酵阶段微生物多样性变化

研究比较不同配比微生物菌剂添加对牛粪-玉米秸秆联合沼气发酵的影响,并采用高通量测序技术对添加了最佳菌剂的沼气发酵液中微生物多样性进行分析。结果表明,最佳玉米秸秆-牛粪发酵条件:微生物菌剂配比为蜡样芽孢杆菌、荧光假单胞菌、枯草芽孢杆菌、松嫩假单胞菌(质量比3∶2∶3∶2),在此条件下最高沼气产率和甲烷产率分别达到了72和39 m L/g VS,最高累积产沼气产率和甲烷产率分别达到了778和532 m L/g VS;高通量测序结果表明,细菌中的拟杆菌门(Bacteroidetes)的数量最为丰富,是最主要的优势类群,在沼气发酵过程中的相对丰度变化趋势为增加,由发酵初期33. 8%增加到发酵末期的43. 6%;真菌中子囊菌门(Ascomycota)的数量最为丰富,是最主要的优势类群,沼气发酵过程中相对丰度变化趋势为先增加后降低,由发酵初期65. 7%增加到发酵中期的84. 7%,又降到发酵末期的66. 8%。     

碱处理对玉米秸秆固态厌氧消化过程中菌群结构的影响

从微生物菌群的动态变化来阐述厌氧消化过程已成为近年的研究热点之一.该文从微生物菌群变化的角度对碱预处理促进纤维质原料厌氧消化性能的原因进行了分析.通过对碱预处理组及对照组典型厌氧消化阶段进行取样、高通量测序后,比较二者在菌群结构方面的差异.结果表明,底物种类及碱处理均对厌氧消化菌群结构有显著影响.实验中共鉴定出10个门...     

厌氧消化污泥干化后热解半焦性质

市政污水污泥厌氧消化再经干化处理后得到的干污泥(D S S)是一种具备一定热值的生物质原料.在常压下采用固定床线性升温的方法热解DSS,利用元素分析、BET、SEM、差热分析、FT-IR等测试手段研究DSS热解后气、液、固三相产物产率以及污泥热解半焦性质.结果表明:通过控制热解温度可以控制三相产物的分布,低于500℃是...     

玉米秸秆不同预处理产沼气对比试验

玉米秸秆直接经过预处理A（对照）,玉米秸秆用复合菌剂绿秸灵预处理B,玉米秸秆用纤维素酶A和纤维素酶B混合预处理C,玉米秸秆和牛粪尿混合预处理D,4种不同预处理方式的玉米秸秆产沼气对比试验。结果表明：用复合菌剂处理过的玉米秸秆试验B,用纤维素酶处理过的玉米秸秆试验C和玉米秸秆与牛粪尿混合试验D,平均产气量均高于直接经过预处理的玉米秸秆对照试验A,分别提高了33．47％,35．76％,36．65％;处理D的秸秆产沼气比处理B和处理C的秸秆产沼气早2天,比处理A（对照）的纯秸秆产沼气早5天。     

不同预处理方法对剩余污泥厌氧消化产沼气过程的影响

研究了不同预处理方法对剩余污泥固态法厌氧消化产沼气过程的影响.结果表明:不同的预处理方法均可不同程度地提高产气量和甲烷含量.其中,经酶法处理后,剩余污泥前4 h产气速率最快,平均每小时为3.29 mL/g;经热处理后,剩余污泥累积产气量最多,为45.80 mL/g,比对照提高了230%;而经微波处理后,剩余污泥所产沼气中甲烷质量分数最高,为62.26%,比对照增加了130%.     

氨氮质量浓度对餐厨垃圾厌氧消化产沼气的影响

实验研究不同氨氮质量浓度对餐厨垃圾厌氧消化过程的影响。实验结果表明:氨氮质量浓度对餐厨垃圾消化过程中出现的两个产气高峰均有显著影响,最高氨氮质量浓度组最大产气速率分别是对照组的44.8%和45%,产气高峰出现时间比对照组分别延迟6 h和42 h。氨氮质量浓度上升导致反应体系中总有机碳去除率降低,由此计算出氨氮抑制餐厨垃圾厌氧消化过程的半抑制浓度为7 860 mg/L。氨氮质量浓度的升高导致挥发性脂肪酸过量积累,其利用速率也相应减缓。     

物理法处理对香蕉秸秆沼气发酵能力影响分析

在中温(37±1)℃条件下,对经物理预处理后获得的纤维长度分别为0.23、2.70、4.10和4.12 cm的4种香蕉秸秆样品进行了批次厌氧发酵试验,考察了物理预处理对香蕉秸秆沼气发酵情况的影响,并分析了利用香蕉秸秆在工业规模制备沼气的可行性。结果表明,物理预处理强度的增强可以提高沼气发酵的日产气量及累积产气量,但对沼气中甲烷含量没有显著影响(甲烷含量在55.54%与63.88%之间)。纤维长度为0.23和2.70 cm时,高日产气量分别为333.6和319.8 mL/d,比4.10 cm和4.12 cm的样品高32.11%34.92%;沼气产率分别为306.49和340.13 mL/g(VS added),比4.10 cm和4.12 cm的样品高8.29%~17.36%。与小麦和玉米秸秆相比,利用香蕉秸秆制备沼气具备较好的应用前景。     

天津静海区秸秆沼气工程运行模式与管理经验

一、项目简介为了贯彻农业部发展秸秆沼气的精神,本刊记者赵梦随中国农业大学林聪教授与北京化工大学李秀金教授赴天津市静海区进行了采访调研。据了解,天津市静海区目前有两处大型秸秆沼气工程,一处位于四党口村,另一处位于南柳木村,工程均采用农业部规划设计研究院研发的秸秆一体化两相厌氧消化工艺（CTP）,由天津旭粲燃气设备有限公司具体建设。     

降解玉米秸秆产纤维素酶和木质素酶菌种的筛选

筛选能降解玉米秸秆产生纤维素酶和木质素酶的菌种,并测定纤维素酶系和木质素酶系的相关酶活.经过筛选得到10株菌株,经鉴定为:Penicillium sp、Altemaria sp、Aspergillus fumigatus、Aspergillus sp、Pestalotiopsis sp、Tricherderma sp、Cephalsporium sp、Pleurotus sp.酶活分析显示,筛选得到的10株菌都有CMC酶、滤纸酶、微晶纤维素酶、Mn过氧化氢酶、漆酶等酶活性;筛选得到的茵株都具有较全面的降解玉米秸秆所需要的酶系,具有较好的玉米秸秆生物降解的研究价值.     

玉米储藏过程中真菌群落结构的影响因素分析

玉米是我国最重要的储粮之一,仓储玉米的真菌污染问题可造成严重的经济损失,危害国家粮食安全。研究仓储玉米真菌群落演变规律,是预防和控制仓储玉米真菌污染的有效手段。本研究以河南和黑龙江采样的仓储玉米为样本,利用高通量测序技术分析样本中真菌群落的组成结构,并分析采样地域、仓储时间、仓储方位、仓储深度等因素对微生物群落的影响。研究结果表明黑龙江和河南仓储玉米的真菌微生物群落组成均以子囊菌门和担子菌门生物为主,采样地域、储存时间和储存深度对仓储玉米中微生物群落具有较大的影响,而仓储玉米在仓库中的位置对仓储玉米微生物群落影响较小。本研究可以为仓储玉米中真菌群落的发生演变模型的建立提供基础数据支持,为仓储玉米真菌控制提供可行方案。     

Short communication: Purple corn (Zea mays L.) stover silage with abundant anthocyanins transferring anthocyanin composition to the milk and increasing antioxidant status of lactating dairy goats

The present study used 16 multiparous lactating Saanen dairy goats (body weight, 41.80 ± 2.92 kg; mean ± standard deviation) with healthy and symmetrical udders. Goats were divided into 2 blocks of 8 goats based on milk yield averaged from 75 d in milk in a randomized completed block design. The 2 study groups were the control (CSSS), in which goats were fed sticky corn stover silage, and the treatment (TPSS), in which goats were fed anthocyanin-rich purple corn (Zea mays L.) stover silage (PSS). The results indicated that the TPSS group led to an elevation in the content of milk lactose relative to the CSSS. The inclusion of anthocyanin-rich PSS had no effect on the level of 5 particular anthocyanins [i.e., cyanidin-3-glucoside, delphinidin, cyanidin, pelargonidin (Pel), as well as total anthocyanins in milk]. The pelargonidin-3-glucoside and malvidin were unable to be detected in both groups. However, the TPSS resulted in higher levels of peonidin (Peo) and malvidin-3-O-glucoside (M3G) compared with the control. Moreover, goats receiving TPSS exhibited a higher level of superoxide dismutase (SOD) in plasma and milk relative to the CSSS. Interestingly, some positive correlations were detected between the certain milk components [i.e., fat and total solids as well as fat and solids-not-fat (SNF); protein and SNF; and total solids and SNF]. In addition, the positive correlations were observed between individual anthocyanins (cyanidin-3-glucoside, delphinidin, Peo, M3G, cyanidin, and Pel) and total anthocyanins. Specifically, stronger positive correlations were noted between several antioxidant enzymes and anthocyanin composition in milk (total antioxidant capacity and Pel; SOD and Peo as well as SOD and M3G). Taken together, PSS with abundant anthocyanins can transfer anthocyanins to the milk and enhance the amount of antioxidants in lactating dairy goats.     

Effect of feeding a corn hybrid selected for leafiness as silage or grain to lactating dairy cattle

A leafy corn hybrid was compared to a grain corn hybrid as silage and high moisture grain to evaluate dry matter intake, milk yield, and milk composition. Sixteen multiparous Holstein cows averaging 97 DIM were used in a feeding trial based on 4 x 4 Latin squares with 21-d periods. Each of four diets contained (dry basis) 8% chopped hay, 42% corn silage, 11% high moisture corn grain, 10% whole, fuzzy cottonseed, and 29% protein concentrate. One diet used leafy corn as both high moisture grain and silage. A second diet contained grain corn hybrid (control) as both high moisture grain and silage. A third diet contained leafy corn for high moisture grain and control corn for silage and the fourth diet used control corn for high moisture grain and leafy corn for silage. Cows fed diets containing leafy silage produced more milk and milk protein and ate more DM than cows fed control silage. The corn hybrid used for high moisture grain did not influence milk yield or composition. Dry matter intake was greater for cows fed the diet containing both leafy high moisture grain and leafy silage than for cows fed both control high moisture grain and control silage, but milk yield and composition were not different. When fed as silage, the leafy corn hybrid used in this experiment supported greater DMI as well as higher milk and protein yields when compared to the grain corn hybrid.     

6种食用菌子实体水提物对肠道菌群的影响

以金针菇、香菇、黑木耳、平菇、双孢菇、杏鲍菇6种常见的市售食用菌子实体为研究对象,利用Illumina Mi Seq PE250二代测序平台对肠道微生物V4区进行富集测序,分析6种食用菌子实体水提物对粪便悬液中肠道菌群的菌群种类和菌群结构的影响。测序结果显示经过不同实验组培养后,不同种类的食用菌子实体对肠道微生物的影响各不相同,金针菇组的厚壁菌门水平较高;香菇组的拟杆菌门、变形菌门、厚壁菌门、双歧杆菌和乳杆菌水平较高;黑木耳组的拟杆菌门、放线菌门、厚壁菌门、双歧杆菌和乳杆菌水平较高;平菇组的拟杆菌门、放线菌门、厚壁菌门和乳杆菌水平较高;双孢菇组的拟杆菌门、放线菌门水平较高;杏鲍菇组的放线菌门水平较高。     

基于高通量测序技术分析凡纳滨对虾(Litopenaeus vannamei)冷藏过程菌群结构变化

目的揭示凡纳滨对虾(4±1)℃条件下贮藏过程中菌群结构的变化规律,为其贮运保鲜提供参考。方法采用高通量测序技术对不同冷藏期凡纳滨对虾中的细菌种类及其丰度迚行分析。结果凡纳滨对虾初始菌群以鞘脂杆菌属(Sphingobacterium)、金黄杆菌属(Chryseobacterium)和寡养单胞菌属(Stenotrophomonas)为主;冷藏过程中,Sphingobacterium、Chryseobacterium、Stenotrophomonas比例迅速减少,系统迚化关系上比较接近的交替假单胞菌属(Pseudoalteromonas)、希瓦氏菌属(Shewanella)和别弧菌属(Aliivibrio)成为优势菌,其中Aliivibrio的比例相对稳定,Shewanella比例呈先增加后减少的趋势,Pseudoalteromonas比例不断增加,可能在凡纳滨对虾腐败过程中起重要作用。结论高通量测序可以更加全面反映凡纳滨对虾中菌群的组成及其丰度信息,Pseudoalteromonas是凡纳滨对虾冷藏过程的优势腐败菌。     

Effects of timing of corn silage supplementation on digestion, fermentation pattern, and nutrient flow during continuous culture fermentation of a short and intensive orchardgrass meal

Using a dual-flow continuous culture fermenter system, this study evaluated the effect of timing of corn silage supplementation on ruminal digestion and nutrient flows following a short and intensive orchardgrass herbage meal. Treatments included 28 g dry matter (DM) of corn silage added either 9 h (9BH; 0700 h) or 1 h (1BH; 1500 h) before adding 42 g DM orchardgrass herbage or no corn silage (control; 70 g DM herbage). Herbage was fed as follows: 66% of the total herbage meal at 1600 h, 22% at 1720 h, and the remaining 12% at 1840 h. Effluent was analyzed for organic matter (OM), crude protein (CP), and neutral detergent fiber (NDF). Purine concentrations in effluent and bacterial isolates were used to estimate the partition of effluent N flow into bacterial and nonbacterial fractions, and to calculate true OM digestibility. Fermenters were sampled for pH, volatile fatty acids (VFA), and NH₃-N at 0730, 1100, 1530, 1600, 1720, 1840, and 2000 h on d 10. Data were analyzed as a 3 × 4 Latin square experimental design. True digestibilities for OM (average of 78.5%) and CP (average of 84.6%), and apparent NDF digestibility (average of 82.7%) were not affected by treatment. Mean ruminal pH was lower for 9BH than for 1BH, averaging 5.6 and 6.5, respectively. Molar proportions of acetate were not affected by treatment. Propionate concentration was greater for 9BH than for 1BH, averaging 20.5 and 18.1 mM, respectively. Diurnal patterns of pH, NH₃-N, and acetate:propionate ratio were affected by treatment: 9BH had the lowest values for all measurements as the day progressed. The NH₃-N concentration and effluent NH₃-N flow were higher for 1BH (11.4 mg/100 mL and 0.26 g/d, respectively) than for 9BH (8.8 mg/100 mL and 0.20 g/d, respectively). Effluent NH₃-N flow (as a % of total N flow) was the lowest for 9BH. Bacterial efficiency was not affected by treatments, with a mean of 10.5 g of N/kg of OM truly digested. Under the same resource allocation (pasture plus supplement), a simple change in timing of corn silage feeding (9 rather than 1 h before an orchardgrass herbage meal) may alter ruminal fermentation pattern. These changes could increase the glucogenic nutrient supply and improve N utilization by reducing ammonia N losses.     

堆沤预处理对玉米秸秆厌氧发酵产气性能及模型

为了促进玉米秸秆的降解,同时使产气高峰提前以达到提高产气速率的目的,对玉米秸秆的预处理方式进行了分析。所采用的方法为堆沤处理,分为加水堆沤和加沼液堆沤两组试验,堆沤时间设为2、4、6、8 d四个不同数值。结果显示,堆沤后各组产气高峰大都有所提前,但峰值产气量并未发生明显变化,甚至稍有降低,可能是玉米秸秆中部分有机物质在堆沤时被消耗所致。作者对发酵时间和产气量进行了模型拟合,拟合效果较好。     

Performance of lactating dairy cows fed ryegrass silage and corn silage with ground corn, steam-flaked corn, or hominy feed

Forty-eight mid-lactation Holstein cows were used in a 6-wk completely randomized block design trial with a 4 × 3 factorial arrangement of treatments to determine the effects of feeding different proportions of corn silage and ryegrass silage with supplemental ground corn (GC), steam-flaked corn (SFC), and hominy feed (HF) on the performance of lactating dairy cows. Forage provided 49% of the dietary dry matter in the experimental diets, which were formulated to meet National Research Council requirements. Ryegrass silage provided 100, 75, 50, or 25% of the total forage dry matter, with corn silage supplying the remainder. There were no interactions between the proportion of forage provided by ryegrass silage and energy supplement. Dry matter intake and milk protein percentage decreased linearly with increasing proportions of ryegrass silage, but milk protein yield was similar among forage treatments. There were no differences among forage treatments in milk yield, milk fat percentage and yield, and energy-corrected milk yield. Dry matter intake was higher and there was a tendency for increased milk fat percentage for GC compared with SFC or HF. No other differences were observed in milk yield or composition among energy supplements. Plasma urea nitrogen and glucose concentrations were similar among treatments. Under the conditions of this trial, our results indicate that feeding a combination of corn silage and ryegrass silage is more desirable than feeding ryegrass silage alone, whereas supplementation with GC, SFC, or HF supports similar levels of milk production.     

Performance of dairy cows fed annual ryegrass silage and corn silage with steam-flaked or ground corn

Twenty-four lactating Holstein cows were used in a 6-wk randomized block design trial with a 2 × 2 factorial arrangement of treatments to determine the effects of feeding ground corn (GC) or steam-flaked corn (SFC) in diets based on either annual ryegrass silage (RS) or a 50:50 blend of annual ryegrass and corn silages (BLEND). Experimental diets contained 49.6% forage and were fed as a total mixed ration once daily for 4 wk after a 2-wk preliminary period. No interactions were observed among treatments. Cows fed BLEND consumed more dry matter (DM), organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) than those fed RS, but total-tract digestibility of OM, NDF, and ADF was greater for RS than for BLEND. No differences in nutrient intake were observed among treatments during wk 4 when nutrient digestibility was measured, but digestibility of DM and OM was greater for SFC than for GC. Cows fed BLEND tended to produce more energy-corrected milk than those fed RS, resulting in improved efficiency (kg of milk per kg of DM intake). When diets were supplemented with SFC, cows consumed less DM and produced more milk that tended to have lower milk fat percentage. Yield of milk protein and efficiency was greatest with SFC compared with GC. Blood glucose and milk urea nitrogen concentrations were similar among treatments, but blood urea nitrogen was greater for cows fed GC compared with those fed SFC. Results of this trial indicate that feeding a blend of annual ryegrass and corn silage is more desirable than feeding diets based on RS as the sole forage. Supplementing diets with SFC improved performance and efficiency compared with GC across forage sources.