摘要
为开发畜禽粪便好氧堆肥的高效降解转化和除臭固氮菌剂,进一步提高堆肥效率和品质,通过菌株产酶和除臭能力分析筛选堆肥发酵功能菌株,分别研制了2种复合菌剂(复合菌剂Ⅰ和复合菌剂Ⅱ),探究添加复合菌剂对鸡粪好氧堆肥常规理化指标、纤维素酶和脲酶活性、氮损失、堆肥产品质量的影响。结果显示:与空白对照组和实验室前期研制的复合菌剂Ⅲ相比,复合菌剂Ⅰ因含有机物质降解能力较高的菌株,能显著增加堆体纤维酶活性,后期纤维素酶酶活高达4.937 U/g;添加复合菌剂Ⅰ可显著提高堆体温度,最高温度可达65.8 ℃,比对照组高5.8 ℃;而复合菌剂Ⅱ因含有除臭能力较强的菌株,能显著降低堆体的脲酶活性和氮损失;添加复合菌剂Ⅱ提高了堆肥产品的总养分含量,堆肥产物总养分可达到5.32%,显著高于对照组(4.52%)。2种复合菌剂均能加快堆肥腐熟,堆肥第7天时,种子发芽指数(GI)值分别为75.12%和75.29%,而对照组GI值仅为47.89%。结果表明,本研究研制的复合菌剂Ⅰ和Ⅱ在鸡粪好氧堆肥应用中有良好的效果,可使堆肥升温、腐熟程度高,增加纤维素酶活性,降低脲酶活性,减少堆肥产物总养分流失和氮损失率。
畜禽粪便是我国最主要的有机固体废弃物来源之一,目前中国每年畜禽粪污产生量近40亿t,但资源化利用率不足75
特定微生物的接种会强化堆肥过程,影响堆肥中的微生物群落,加速堆料分解并提高堆肥产品的腐殖质含
本研究针对好氧堆肥过程周期长、氮损失和氨挥发严重、堆肥产品品质差等问题,有针对性地研制高效降解转化和除臭固氮菌剂,并探究其在鸡粪堆肥中的应用效果,为扩大复合菌剂在堆肥中的应用,进一步提高有机肥生产效率和品质提供实践依据。
本研究中所用菌株均来自笔者所在课题组前期从不同堆肥和土壤样品中分离的原有保存菌株。其中,饲料类芽胞杆菌(Paenibacillus pabuli) 5-1、台中类芽胞杆菌(Paenibacillus taichungensis) 6-6和红球菌(Rhodococcus hoagii) K4-1在中国典型培养物保藏中心的保藏编号分别为CCTCC NO:M2021574、CCTCC NO:M2021575和CCTCC NO:M2021573。复合菌剂Ⅲ是笔者所在课题组曹蕊前期研制的堆肥菌剂配方(枯草芽胞杆菌BS2∶解淀粉芽胞杆菌Ba∶地衣芽胞杆菌BL1∶酿酒酵母SC=3∶1∶3∶4)(专利号:ZL202010616986.0)。
堆肥原材料鸡粪来自华中农业大学实验鸡场,辅料锯末来自华中农业大学动物医院。
Vario PYRO cube元素分析仪,德国Elementar;LH3-CNP氨氮总磷测定仪,杭州陆程仪器有限公司;722E紫外分光光度计,上海光谱仪器有限公司;WT20003电热恒温培养箱,上海天呈实验仪器制造有限公司;AB204-N分析天平,瑞士METTLER TOLEDO。
将待测菌株分别接种于酪素培养基、淀粉培养基、刚果红羧甲基纤维素钠培养基,观察菌落周围是否有无色透明圈出现,计算出透明圈直径和菌落直径之比,判断菌株产蛋白酶、淀粉酶、纤维素酶能力。
将各个菌株分别接种到含10% NH
采用打孔法对功能菌株之间的拮抗性进行测定,将菌株分别制备成菌悬液,均匀涂抹至培养基表面,使用打孔器等距离四点打孔及中心打孔,并将孔底部进行火焰封底,吸取其余待测菌株菌悬液50 μL加入孔中,以空白液体培养基为对照,于37 ℃培养24 h后观察打孔周围抑菌圈情况并测量其直径。在混合培养基发酵过程中,分别取4株菌OD600值为1.0左右的菌液,添加菌悬液量,采用4因素3水平的正交试验确定9种不同组合,最终确定菌株的最佳配伍。发酵过程中活菌数采用平板涂布法计数,并测定其吸光值(OD600)。
1)鸡粪好氧堆肥试验。鸡粪因含有较高的氮素养分,是有机肥生产常用的原材料。本研究堆肥试验于2020年12月在华中农业大学试验养鸡场内进行。堆肥试验采用鸡粪为原材料,锯末为堆肥辅料。其中,测定堆肥原材料锯末和鸡粪的初始C/N和含水率,锯末的C/N为125.6,含水率为10.45%;鸡粪的C/N为8.72,含水率为71.69%。调节堆肥C/N比为25∶1左右,含水率为50%~60%,最终按鸡粪∶锯末=6∶1比例充分混合。共设置4个处理组,空白对照组(CK)、复合菌剂Ⅰ组(ABⅠ)、复合菌剂Ⅱ组(ABⅡ)、复合菌剂Ⅲ组(ABⅢ)。本研究的复合菌剂Ⅰ和Ⅱ是在复合菌剂Ⅲ的基础上进行改进。在堆肥起始时将复合菌剂按堆体体积的1%比例进行喷洒添加,混匀。
堆肥箱连接通风系统进行鼓风,整个堆肥试验在环境温度17~20 ℃的温室小棚内进行。堆肥试验装置为容积60 L、厚度30 mm的EPS泡沫箱(高280 mm、长540 mm、宽400 mm)。泡沫箱底部铺满3 cm左右的锯末作为通风缓冲层,侧面开1个小孔便于测定温度,定时通风,保证均匀的通风量。在为期14 d的鸡粪好氧堆肥过程中,各试验组的温度均经历了升温期、高温期、降温期和腐熟期,分别于堆肥第1天、第4天、第7天和第14天采集样品。采用5点取样法用无菌小铲采集堆体样品,混合均匀,置于样品袋中,分别于4 ℃和-20 ℃冰箱保存。
2)堆肥常规理化性质的测定。堆肥理化指标的测定方法参照农业行业标准NY/T 525-2012《有机肥料》进行,分别测定堆肥过程中温度、含水率、pH、种子发芽指数(GI)和有机质含量的变化。称取新鲜堆肥样品5~10 g放入坩埚内,于105 ℃的烘箱中烘干后粉碎过筛,精确称量4~5 mg烘干样品,研磨使其粒径小于0.15 mm,用锡箔纸包被,使用元素分析仪测量样品中总C、N含量。铵态氮采用氯化钾浸提⁃靛酚蓝比色法测定、硝态氮测定采用双波长紫外⁃分光光度法。纤维素酶活性采用3,5-二硝基水杨酸(DNS)法测定,脲酶活性采用比色法测定。
将实验室前期从不同堆肥和土壤样品分离的22株菌,进行菌株降解产酶活力和除NH3能力分析,结果发现,饲料类芽胞杆菌5-1和台中类芽胞杆菌 6-6产淀粉酶和纤维素酶活力较高,解淀粉芽胞杆菌(Bacillus amyloliquefaciens) 6-1和枯草芽胞杆菌(Bacillus subtilis) 8-3产蛋白酶和纤维素酶活力较高(
将各菌株制备成菌悬液后分别与烧杯中的鸡粪混合均匀,测定其NH3去除能力。结果发现,饲料类芽胞杆菌5-1、台中类芽胞杆菌6-6和红球菌K4-1对鸡粪释放NH3的去除能力较高,分别达到15.76%、10.87%和7.07%,将这些菌株用于堆肥固氮除臭复合菌剂Ⅱ的研制。
通过打孔法进行菌株间的拮抗试验,结果显示,选取的功能菌株间不存在拮抗作用。复合菌剂Ⅰ由降解酶活较高的饲料类芽胞杆菌5-1、解淀粉芽胞杆菌6-1、台中类芽胞杆菌6-6和枯草芽胞杆菌8-3组成;复合菌剂Ⅱ由去除NH3能力较好的饲料类芽胞杆菌 5-1、台中类芽胞杆菌6-6、红球菌 K4-1、酿酒酵母菌(Saccharomyces cerevisiae) SC组成(SC为本课题组曹蕊筛选的能利用不同氮源、有除臭效果的酿酒酵母菌株)。通过复配正交试验,最终确定复合菌剂Ⅰ最优组成为5-1∶6-1∶6-6∶8-3=2∶3∶2∶3,复合菌剂Ⅱ最优组成为5-1∶6-6∶K4-1∶SC=2∶2∶2∶1。
整个堆肥过程主要分为4个阶段:升温期、高温期、降温期和腐熟期。温度是从表观上直接呈现堆肥进程的指标。如

图1 复合菌剂接种鸡粪堆肥过程中温度(A)、pH(B)、含水率(C)和种子发芽指数(D)的变化
Fig. 1 Changes of physicochemical indexes including temperature(A),pH(B),moisture(C)and seed germination index (D) during composting of chicken manure inoculated with compound microbial inoculants
CK:对照组The control group; AB Ⅰ:复合菌剂Ⅰ组Compound microbial inoculant Ⅰgroup; ABⅡ:复合菌剂Ⅱ组Compound microbial inoculant Ⅱ group;AB Ⅲ:复合菌剂Ⅲ组Compound microbial inoculant Ⅲ group.下同The same as below.
pH可以反映堆肥过程中微生物生长酸碱环境,适宜的pH有利于微生物生长,降低pH可抑制氨气挥发。如
适宜的含水率有利于微生物生长,如
各试验组白菜种子发芽情况如
水溶性铵态氮和硝态氮的变化是粪便堆肥中氮素变化的重要指标。如

图2 堆肥过程中铵态氮(A)、硝态氮(B)和总氮(C)含量的变化
Fig. 2 Changes of ammonium nitrogen (A),nitrate nitrogen (B) and total nitrogen (C) content during composting
总氮含量变化可判断堆肥过程中氮素损失程度。堆体温度快速升高导致氨挥发,可造成氮损失。在堆肥结束时,比较CK组、复合菌剂Ⅰ组、复合菌剂Ⅱ组、复合菌剂Ⅲ组的氮损失。由
高纤维素酶活性有利于堆体中纤维素类物质分解。如

图3 添加复合菌剂鸡粪堆肥过程中纤维素酶(A)和脲酶活性(B)变化
Fig. 3 Changes of cellulase (A) and urease (B) activity during chicken manure composting with compound microbial inoculants
*P<0.05;**P<0.01;***P<0.001.下同The same as below.
如
有研究表明,芽胞杆菌属细菌可分泌纤维素酶来分解堆肥混合物中的纤维素和木质
鸡粪由于铵态氮含量高导致氨挥发产生异味,如果将氨氧化为亚硝酸盐、硝酸盐能有效降低氨的挥发从而减少对环境的污染。本研究中的饲料类芽胞杆菌5-1、台中类芽胞杆菌6-6和红球菌K4-1降低了鸡粪试验组中的NH3浓度并且减少了NH
在好氧堆肥中接种微生物菌剂是加快畜禽粪便无害化和腐熟的方法之一。本研究中添加复合菌剂能显著提高堆肥温度,这可能是因为添加微生物菌剂促进了有机物的降解,使得堆体温度快速上升,加快堆肥腐熟进程。尤其是复合菌剂Ⅰ能提高堆体温度5.8 ℃,可能是复合菌剂Ⅰ是由产酶活力高的菌株组成,显著加快了有机物的降解。也有研究表明,添加复合菌剂促进堆体物质分解,释放更多热量,当高温持续3 d以上可以有效消除鸡粪堆体中的病原微生物和杂草,达到无害化处理标
堆肥腐熟度影响堆肥质量,种子发芽指数是目前广泛应用的判断堆肥腐熟度的重要方
本研究发现,复合菌剂Ⅰ因含有产淀粉酶、蛋白酶和纤维素酶能力较高的菌株,能有效促进堆肥中有机物质的降解,显著增加堆体纤维酶活性、提高堆体温度、加快堆肥腐熟,但也因堆肥温度的提高,使得氨气挥发更为严重,从而有较多的氮损失。而复合菌剂Ⅱ因含有除氨能力较高的菌株,能显著降低堆体的脲酶活性和氮损失,从而使堆肥产品具有最高的总养分含量。添加复合菌剂可以调控堆肥过程中的氮代谢,减少氮素物质转化为氨,或吸附堆体内铵态氮,或促进铵态氮转化为硝态氮,或通过生物转化将氮固定储存,从而减少氨的产生。Guo
参考文献References
GONG B, ZHONG X, CHEN X, et al. Manipulation of composting oxygen supply to facilitate dissolved organic matter (DOM) accumulation which can enhance maize growth[J/OL]. Chemosphere, 2021, 273:129729[2022-04-08].https://doi.org/10.1016/j.chemosphere.2021.129729. [百度学术]
ALEGBELEYE O O,SANT'ANA A S.Manure-borne pathogens as an important source of water contamination:an update on the dynamics of pathogen survival/transport as well as practical risk mitigation strategies[J/OL].International journal of hygiene and environmental health,2020,227:113524[2022-04-08]. https://doi.org/10.1016/j.ijheh.2020.113524. [百度学术]
KIM J K, LEE D J, RAVINDRAN B, et al. Evaluation of integrated ammonia recovery technology and nutrient status with an in-vessel composting process for swine manure[J]. Bioresource technology, 2017, 245:365-371. [百度学术]
赵彬涵,孙宪昀,黄俊,等.微生物在有机固废堆肥中的作用与应用[J].微生物学通报,2021,48(1):223-240.ZHAO B H,SUN X Y,HUANG J,et al.Application and effects of microbial additives in aerobic composting of organic solid wastes:a review[J].Microbiology China,2021,48(1):223-240(in Chinese with English abstract). [百度学术]
LI Y,GU J,ZHANG S Q,et al.Effects of adding compound microbial inoculum on microbial community diversity and enzymatic activity during co-composting[J].Environmental engineering science, 2018, 35(4):270-278. [百度学术]
DUAN M L,ZHANG Y H,ZHOU B B,et al.Effects of Bacillus subtilis on carbon components and microbial functional metabolism during cow manure-straw composting[J/OL].Bioresource technology,2020,303:122868[2022-04-08].https://doi.org/ 10.1016/j.biortech.2020.122868.. [百度学术]
周东兴,王广栋,邬欣慧,等.腐熟堆肥中维素降解菌筛选鉴定及酶学特性研究[J].东北农业大学学报,2018,49(5):60-68.ZHOU D X,WANG G D,WU X H,et al.Compost isolation and enzymatic characteristics of cellulose-decomposing bacteria[J].Journal of Northeast Agricultural University,2018,49(5):60-68(in Chinese with English abstract). [百度学术]
PÉREZ R,TAPIA Y,ANTILÉN M,et al. Interactive effect of compost application and inoculation with the fungus Claroideoglomus claroideum in Oenothera picensis plants growing in mine tailings [J/OL]. Ecotoxicology and environmental safety, 2021, 208:111495[2022-04-08]. https://doi.org/10.1016/j.ecoenv.2020.111495. [百度学术]
KUMAR A,KUMAR A,PRATUSH A.Molecular diversity and functional variability of environmental isolates of Bacillus species[J/OL].Springer plus,2014,3:312[2022-04-08].https://doi.org/10.1186/2193-1801-3-312. [百度学术]
YIN Y N,GU J,WANG X J,et al.Effects of rhamnolipid and Tween-80 on cellulase activities and metabolic functions of the bacterial community during chicken manure composting[J/OL].Bioresource technology,2019,288:121507[2022-04-08].https://doi.org/10.1016/j.biortech.2019.121507. [百度学术]
LIU X M,LI Q,LI Y B,et al.Paenibacillus strains with nitrogen fixation and multiple beneficial properties for promoting plant growth[J/OL].Peer J,2019,7:e7445[2022-04-08].https://doi.org/10.7717/peerj.7445. [百度学术]
KO C H,YANG C Y,CHANG F C, et al. Effect of Paenibacillus cellulase pretreatment for fiber surface[J/OL]. Journal of environmental management,2019, 241:1331[2022-04-08].https://doi.org/10.1016/j.jenvman.2019.03.1331. [百度学术]
BAI F L,TIAN H,MA J.Landfill leachate treatment through the combination of genetically engineered bacteria Rhodococcus erythropolis expressing Nirs and AMO and membrane filtration processes[J/OL].Environmental pollution,2020,263: 114061[2022-04-08].https://doi.org/10.1016/j.envpol.2020.114061. [百度学术]
FRIEDRICH K L,SOUZA A D R,FIA R,et al.Nitratation in pilot-scale bioreactors fed with effluent from a submerged biological aerated filter used in the treatment of dog wastewater[J].Environmental technology,2021,42(24):3852-3862. [百度学术]
JAIN M S,JAMBHULKAR R,KALAMDHAD A S.Biochar amendment for batch composting of nitrogen rich organic waste:effect on degradation kinetics,composting physics and nutritional properties[J].Bioresource technology,2018,253:204-213. [百度学术]
LUO Y,LIANG J,ZENG G M,et al.Seed germination test for toxicity evaluation of compost:its roles,problems and prospects[J].Waste management,2018,71:109-114. [百度学术]
MOHAMED O Z,YASSINE B,HILALI RANIA E,et al.Evaluation of compost quality and bioprotection potential against Fusarium wilt of date palm[J].Waste management,2020,113:12-19. [百度学术]
GUO H, GU J, WANG X, et al. Beneficial effects of bacterial agent/bentonite on nitrogen transformation and microbial community dynamics during aerobic composting of pig manure[J/OL]. Bioresource technology, 2020, 298:122384[2022-04-08]https://doi.org/10.1016/j.biortech.2019.122384. [百度学术]
MAO H,Lü Z Y,SUN H D,et al.Improvement of biochar and bacterial powder addition on gaseous emission and bacterial community in pig manure compost[J].Bioresource technology,2018,258:195-202. [百度学术]
CHEN X, CHENG W, LI S, et al. The “quality” and “quantity” of microbial species drive the degradation of cellulose during composting[J/OL]. Bioresource technology, 2021, 320:124425[2022-04-08].https://doi.org/10.1016/j.biortech.2020.124425. [百度学术]
HU T,WANG X J,ZHEN L S,et al.Effects of inoculating with lignocellulose-degrading consortium on cellulose-degrading genes and fungal community during co-composting of spent mushroom substrate with swine manure[J/OL].Bioresource technology,2019,291:121876[2022-04-08].https://doi.org/10.1016/j.biortech.2019.121876. [百度学术]
ZHANG H L,WEI J K,WANG Q H,et al.Lignocellulose utilization and bacterial communities of millet straw based mushroom (Agaricus bisporus) production[J/OL].Scientific reports,2019,9:1151[2022-04-08]. https://doi.org/10.1038/s41598-018-37681-6. [百度学术]
JURADO M M,SUÁREZ-ESTRELLA F,VARGAS-GARCÍA M C,et al.Evolution of enzymatic activities and carbon fractions throughout composting of plant waste[J].Journal of environmental management,2014,133:355-364. [百度学术]
BOHACZ J.Changes in mineral forms of nitrogen and sulfur and enzymatic activities during composting of lignocellulosic waste and chicken feathers[J].Environmental science and pollution research international,2019,26(10):10333-10342. [百度学术]