Isolation and Characterization of a Thermophilic Oil-Degrading Bacterial Consortium

In this study, a thermophilic oil-degrading bacterial consortium KO8-2 growing within the temperature range of 45-65 ℃ (with 55 ℃ being the optimum temperature) was isolated from oil-contaminated soil of Karamay in Xinjiang, China. Denaturing gradient gel electrophoresis (DGGE) showed that there were nine strains included in KO8-2, which originated from the genera of Bacillus, Geobacillus and Clostridium. They all belonged to thermophilic bacteria, and had been previously proved as degraders of at least one petroleum fraction. The crude oil degraded by KO8-2 was analyzed by infrared spectrophotometry, hydrocarbon group type analysis and gas chromatography. The results indicated that the bacterial consortium KO8-2 was able to utilize 64.33% of saturates, 27.06% of aromatics, 13.24% of resins and the oil removal efficiency reached up to 58.73% at 55 ℃ when the oil concentration was 10 g/L. Detailed analysis showed that KO8-2 was able to utilize the hydrocarbon components before C 19 , and the n-alkanes ranging from C 20 -C 33 were signifi- cantly degraded. The ratios of nC 17 /Pr and nC 18 /Ph were 3.12 and 3.87, respectively, before degradation, whereas after degradation the ratios reduced to 0.21 and 0.38, respectively. Compared with the control sample, the oil removal efficiency in KO8-2 composting reactor reached 50.12% after a degradation duration of 60 days.

Chemical behaviors of different arsenic-bearing sulphides bio-oxidated by thermophilic bacteria

The study on arsenopyrite and realgar of bacterial oxidation shows that the chemical behaviors of different arsenic-bearing sulphides oxidated by thermophilic bacteria are quite distinct. Arsenopyrite is active and quickly eroded in bacteria-bearing solution. With a high leaching rate over 95%, the arsenopyrite phase cannot be detected by X-ray diffraction(XRD). Arsenopyrite is highly toxic to bacteria that at the initial stage of bio-oxidation, bacterial growth is inhibited and the number of bacterium cell drops from 2.26 × 108/mL to the lowest 2.01 × 105/mL. At the later stages of bio-oxidation, bacteria grow fast and reach 2.23 × 108/mL. Comparably, realgar is inertial and resistive to bacterial corrosion and oxidation. Arsenic in realgar crystal is hard to be leached and the residue is still realgar phase, as indicated by XRD. The cell number of bacteria varies a little, decreasing from 2.26 × 108/mL to 2.01 × 107/mL, during the bacterial oxidation. The results show that the crystal structure and arsenic valency of arsenic-bearing sulphides play a vital role during the leaching process of bacterial oxidation.

Effect of mixed moderately thermophilic adaptation on leachability and mechanism of high arsenic gold concentrate in an airlift bioreactor

A refractory gold concentrate with 19% arsenic was treated by a mixed moderately thermophiles in an airlift bioreactor through an adaptation protocol. The moderately thermophiles could respond well to 20%(w/v) pulp density with less than 10% loss of productivity, and resist arsenic up to 15 g/L. There were a lot of jarosite, arsenolite and sulfur, but not scorodite and ferric arsenate in the bioleached residue. Jarosite passivation and lower sulfur-oxidizing activity of the cells due to the toxicity of the high concentrations of soluble arsenic and iron ions at low p H value should mainly response for the incomplete extraction at high pulp density. The initial bacterial community did not change in nature except for new found P aeruginosa ANSC, but sulfur-oxidizing microorganisms have been dominant microorganisms after a long time of adaptation. Pseudomonas aeruginosa originating from the gold concentrate should be closely relative to the metabolism of the organic matters contained in the refractory gold concentrate.

在酵母粉或Cu^(2+)胁迫下古菌Ferroplasma thermophilum与两种中度嗜热细菌的协同作用

本研究目的为考察在酵母粉或Cu2+胁迫下,古菌Ferroplasma thermophilum在分别与其他两种中度嗜热细菌(Leptospirillum ferriphilum和Acidithiobacillus caldus)混合培养体系中的生态功能。实验在250 mL摇瓶中进行,采用纯培养与混合培养对照的方法,结合荧光定量PCR(Quantitive PCR,Q-PCR)技术考察F.thermophilum分别与其他两种中度嗜热菌之间的协同作用。结果表明:在0.04%(w/v)酵母粉胁迫下,L.ferriphilum YSK纯培养物的生长受到完全抑制,而At.caldus s2纯培养物的生长不受抑制。F.thermophilum L1与L.ferriphilum YSK混合培养减轻了酵母粉对L.ferriphilum YSK的抑制作用且促进其生长;F.thermophilum L1/At.caldus s2混合培养体系中,F.thermophilum L1的加入能够促进平稳期At.caldus s2的生长。在5 g/L Cu2+胁迫下,F.thermophilum L1与L.ferriphilum YSK混合培养时,F.thermophilum L1生长被促进,而L.ferriphilum YSK的生长受到抑制;F.thermophilumL1与At.caldus s2混合培养能够有效地促进彼此生长,且协同促进铁/硫氧化代谢。

城市污水厂脱水污泥好氧发酵强化技术及效果

以市政污水厂脱水污泥为主要原料,采用温度反馈控制的污泥好氧发酵设备,研究了翻抛模式、菌种以及活性炭辅料对污泥好氧发酵强化工艺的影响效果。试验结果表明:堆体翻抛模式在升温期采用时间控制,而在高温期温度控制,能缩短升温期延长高温期;添加耐高温菌种和活性炭能提升堆体升温速率,12 h内快速升温至60℃以上,高温期温度可提升至70℃以上,促进发酵产物快速腐熟;添加活性炭能增加堆体孔隙率,促进堆体内部充氧,提升好氧反应效率,同时实现水厂的废弃活性炭资源化利用。发酵产物参考有机肥料要求,用于种植油菜和波斯菊,通过对比试验看出,发酵产物明显增加植物生长速度,提升密度,强壮茎叶。发酵产物可用于园林绿化,提升土壤肥力,实现污泥资源化利用。

嗜热厌氧菌共培养发酵玉米秸秆产氢的研究

氢能是对环境无害且可以替代化石燃料的可持续性能源。利用嗜热厌氧菌暗发酵木质纤维素生产氢气是一种极具潜力的生物制氢技术,具有清洁、高效和可再生的优势。构建解糖热解纤维素菌和热解糖厌氧杆菌共培养体系,考察两株菌株接种比例、总接种量和底物浓度对玉米秸秆发酵产氢的影响。实验结果表明,在发酵体系初始pH值7.0,培养温度60℃条件下,当解糖热解纤维素菌和热解糖厌氧杆菌接种比例为3∶2,菌种总接种量为6%,秸秆浓度为15 g·L^(-1)时,体系产氢能力最强。此时,发酵体系产氢量累积达到65.6 mL·g-1-秸秆,氢气含量为46.9%,最大产氢速率为1.47 mL·g^(-1)h^(-1)。

Isolation and molecular identification of cellulolytic bacteria from Dig Rostam hot spring and study of their cellulase activity

Cellulose is the main structural component of lignocellulosic wastes that can be converted to sugars and biofuels by cellulase.Due to wide applications of this enzyme in various industries around the world,cellulase is considered as the third industrial enzyme.The ability of thermophilic bacteria in the production of heat-stable cellulases has made them valuable tools in biotechnology.The aim of this study was isolation and molecular identification of cellulolytic thermophile bacteria from Dig Rostam hot spring and investigating their cellulase activity.Samples were taken from water and sediments of this hot spring,and cellulolytic bacteria were enriched in media containing cellulose as the only carbon source.The bacteria were incubated at 60℃,and single colonies were then isolated on solid media.Congo red assay was used as a quick test for the qualitative screening of cellulase activity.According to these qualitative results,four colonies named CDB1,CDB2,CDB3,and CDB4 were isolated,and their growth curve and some other characteristics were determined by biochemical assays.Moreover,endoglucanase,exoglucanase,and FPase activities of the isolates were investigated quantitatively.Results indicated that CDB1 exhibited the highest endoglucanase(0.096 U/mL)and exoglucanase(0.156 U/mL)activities among other isolates.16S rDNA partial sequencing indicated that CDB1 had 99%similarity to the genus Anoxybacillus,and the other isolates showed the highest similarity to the genus Geobacillus.The cellulase gene of CDB1 isolate with the highest cellulase activity was also cloned,and its sequence is reported for the first time.Further studies on this thermophilic enzyme might be useful for industrial applications.

嗜热复合菌对堆肥品质及微生物群落演替的影响

【目的】研究嗜热复合菌对畜禽粪污堆肥理化特性和腐熟度的影响,探讨嗜热菌影响堆肥过程的微生物机制。【方法】堆料由75%羊粪和25%养鸡发酵床垫料构成,初始原料C/N为28,堆料量1.2 t,高度70~90 cm,开放条垛式堆沤。处理组为堆肥添加0.1%嗜热菌B.fordii FJAT-51578和U.thermosphaericus FJAT-51579等比混合的发酵液,对照组为添加1%市售枯草芽孢杆菌堆肥菌剂(Bacillus subtilis)。堆肥时间为2021年9月18日—10月14日,每两天检测1次温度。堆肥前15天,每两天进行一次翻抛,后期每5天进行一次翻抛,保持堆肥含水量50%~60%,直至高温期结束。在堆肥开始后第1、9和26天取堆肥样品,分析氮磷含量、硝化指数和种子发芽指数。结合扩增子测序,分析堆肥细菌群落结构变化,并揭示其主要环境影响因子。采用PICRUSt分析堆肥有效氮和有效磷代谢的微生物机制。【结果】嗜热复合菌添加促进堆肥硝化指数的降低和种子发芽指数的升高,促进堆肥腐熟;堆肥产物碱解氮和有效磷的含量分别比市售菌剂组高11.8%和7.7%。同时,嗜热复合菌的添加改变了细菌群落的分布,降低了堆肥细菌的多样性和丰富度,提高了糖单胞菌、链霉菌和嗜热葡萄孢菌等降解菌的丰度。RDA分析表明,pH和C/N是影响堆肥微生物群落多样性的主要因素,碱解氮与芽孢杆菌和糖单胞菌属丰度正相关,有效磷与嗜热裂孢菌、直丝菌属和马杜拉放线菌属丰度正相关。氮、磷代谢相关京都基因和基因组百科全书同源基因(KO)的PICRUSt分析显示,微生物氮磷循环相关KO的丰度随着堆肥进程均有所增加。添加嗜热菌剂提高了氨化、铵同化、硝酸盐同化、同化/异化硝酸盐还原等氮循环相关KO,及无机磷溶解、酸性磷酸酶和碱性磷酸酶等磷循环相关KO。【结论】在畜禽粪污堆肥中添加嗜热复合菌剂加快并延长了高温期,降低了C/N,提高了堆肥中碱解氮和有效磷含量,其中C/N、硝化指数和GI指数等指标在堆肥中期达腐熟程度标准,促进堆肥腐熟。堆肥中添加嗜热复合菌剂增加了细菌氮磷代谢相关KO的表达,提高了腐熟中期堆肥中嗜热菌的丰度和种类,碱解氮与芽孢杆菌和糖单胞菌属丰度呈正相关,有效磷与嗜热裂孢菌、直丝菌属和马杜拉放线菌属丰度正相关。因此,添加嗜热复合菌促进了堆肥有效氮磷的含量。

可降解材料生物降解率的检测方法比较

基于现行的材料降解率测定标准及特定微生物的降解性能,设计了4种材料降解率的检测方法,即++两种标准方法(接种物:腐熟堆肥、蛭石腐熟堆肥浸提液)和两种实验方法(接种物:蛭石芽孢杆菌、+蛭石嗜热菌).采用生产环保胶带所用的原纸、塑料薄膜(主要成分为polylactic acid,PLA)和胶带成品作为受测材料,对比不同处理方法下材料降解性能的效率.结果表明,在60 d的实验周期中,原纸和+PLA薄膜在4种方法处理下均呈现快速降解.然而,胶带成品降解率在腐熟堆肥、蛭石腐熟堆肥浸提液++处理下上升缓慢;在蛭石芽孢杆菌处理下略高;在蛭石嗜热菌处理下上升速率显著高于其他处理方法(约1.7~7.5倍).添加微生物菌剂尤其是嗜热菌,能有效提升产品降解率的测定效率.因此,优化降解接种物的方法可提高材料降解率的测试效率,有利于企业缩短可降解材料的研发及生产周期.

高温持续时间对鸡粪堆肥中多重耐药菌、接合型质粒及耐药基因消减特征的影响

为研究堆肥过程中高温持续时间对多重耐药大肠杆菌及其携带的接合型质粒和抗生素耐药基因(Antibiotic resistance gene,ARGs)消减规律的影响,本研究在鸡粪堆肥初始物料中外源添加多重耐药大肠杆菌菌液,并设置延长高温时间组(CT组)和常规堆肥组(NT组)两种堆肥条件处理,利用选择性培养及16S rRNA基因扩增子测序技术检测多重耐药菌群变化规律,同时利用数字PCR定量检测大肠杆菌16S rRNA基因、接合型质粒转移酶基因(MOBP)、氨基糖苷类耐药基因[APH(3)-Ib]及磺胺类耐药基因(sul2)和Ⅰ类整合子-整合酶基因(intl1)等污染物相对丰度变化,对比获得了延长高温时间对多重耐药菌及其ARGs消减速率的影响。结果表明,高温堆肥能够明显抑制堆肥中多重耐药菌的生长,并且CT组对其的抑制效果明显好于NT组。堆肥结束后,五种基因在CT组的相对丰度消减率为79.82%~99.99%,但NT组中腐熟期结束后APH(3)-Ib、sul2、intl1等基因相对丰度均高于初始物料。多重耐药大肠杆菌及其接合型质粒的消减规律均符合一级动力学方程,但APH(3)-Ib、sul2和intl1等基因在NT组的消减动力学却呈现明显的两段化特征,延长高温时间(CT组)能够抑制腐熟期出现的反弹。细菌群落结构分析表明,NT组中ARGs丰度再次增加与Moheibacter、Halomonas等菌属的富集相关。本研究表明,在堆肥过程中,延长高温持续时间,可降低堆体中部分ARGs潜在宿主菌的丰度,阻断其垂直传播的作用,最终减少成品肥中ARGs的丰度。

Characterization of sulfide oxidation and optimization of sulfate production by a thermophilic Paenibacillus naphthalenovorans LYH-3 isolated from sewage sludge composting

The sulfur-containing odor emitted from sludge composting could be controlled by sulfide oxidizing bacteria, yet mesophilic strains show inactivation during the thermophilic stage of composting. Aimed to investigate and characterize the thermotolerant bacterium that could oxidize sulfide into sulfate, a heterotrophic strain was isolated from sewage sludge composting and identified as Paenibacillus naphthalenovorans LYH-3. The effects of various environmental factors on sulfide oxidation capacities were studied to optimize the sulfate production, and the highest production rate (27.35%±0.86%) was obtained at pH 7.34, the rotation speed of 161.14 r/min, and the inoculation amount of 5.83%by employing BoxBehnken design. The results of serial sulfide substrates experiments indicated that strain LYH-3 could survive up to 400 mg/L of sulfide with the highest sulfide removal rate (88.79%±0.35%) obtained at 50 mg/L of sulfide. Growth kinetic analysis presented the maximum specific growth rateμm(0.5274 hr-1) after 22 hr cultivation at 50℃. The highest enzyme activities of sulfide quinone oxidoreductase (0.369±0.052 U/mg) and sulfur dioxygenase (0.255±0.014 U/mg) were both obtained at 40℃, and the highest enzyme activity of sulfite acceptor oxidoreductase (1.302±0.035 U/mg) was assessed at 50℃. The results indicated that P. naphthalenovorans possessed a rapid growth rate and efficient sulfide oxidation capacities under thermophilic conditions, promising a potential application in controlling sulfur-containing odors during the thermophilic stage of sludge composting.

极耐热α-L-鼠李糖苷酶的性质及其在异槲皮素制备中的应用研究

L-鼠李糖苷酶可特异性切除糖苷类化合物上连接的α-L-鼠李糖基,已被广泛用于食品、医药等工业领域。作者旨在获得耐受高温的α-L-鼠李糖苷酶,提高工业生产的效率和降低使用成本。首先对嗜热菌Sulfolobus islandicus来源的α-L-鼠李糖苷酶基因进行克隆及大肠杆菌的异源表达,随后测定了系列酶学性质,接着优化了该酶制备异槲皮素的酶法制备工艺。结果表明:重组酶SisRha在90℃下酶活力最佳,具有极好的热稳定性,其在80℃下孵育120 min后酶活力几乎没有损失;最适反应pH为5.5,在pH 4.5~7.0时,pH稳定性良好;重组酶SisRha对人工底物对硝基苯酚鼠李糖糖苷(p NPR)的Km值为(0.15±0.03) mmol/L,Vmax值为(6.26±0.51)U/mg,k_(cat)值为(10.48±0.86) s^(-1);对底物p NPR、芦丁、朝藿定C、柚皮苷、橘皮苷和淫羊藿苷的比活力分别为25.06、11.89、6.74、3.14、2.77、0.42 U/mg。重组酶SisRha转化芦丁生成异槲皮素的适宜工艺为:用酶量0.40 U/mL,在85℃、pH 5.0的条件下反应1 h,可将2 mmol/L芦丁几乎全部转化,摩尔转化率高达98.56%。本研究丰富了现有的α-L-鼠李糖苷酶资源,为嗜热菌来源的α-L-鼠李糖苷酶的研究奠定了基础,同时提供了一种高温转化芦丁制备异槲皮素的方法。

一株产淀粉酶的嗜热地衣芽孢杆菌的筛选及鉴定

目前,需要将能在高温、高盐和碱性等极端环境中稳定的淀粉酶利用于农业生产中。从云南腾冲热泉附近的土壤样品中分离得到一株菌株,经验证其为一株能够产淀粉酶的嗜热菌。通过测定该菌的16S rRNA基因序列,进行序列比对和构建系统发育树,结合菌落和菌体形态的观察,确定了该菌的分类学地位,并利用非发酵细菌生化鉴定研究了该菌的生理生化性质。结果表明,该菌株为革兰氏阳性细菌,属于地衣芽孢杆菌,命名为CHJ05;通过不同温度和不同pH条件下的生长实验,确定了该菌生长的最佳温度为45℃,最适pH为9,还能在10%NaCl的高盐环境中稳定生长。该菌所产的淀粉酶在30~40℃和pH6~10能保持较高活性,Zn^(2+)、Ca^(2+)、Mg^(2+)三种金属离子对酶活有促进作用,Mn^(2+)和Fe^(2+)对酶活有抑制作用。因此,CHJ05为一株能在高温、高盐以及碱性条件下稳定生长的菌株,为研究和开发在极端环境中继续产淀粉酶的菌株扩大资源储备。

蚕丝丝肽嗜热栖热菌发酵液对皮肤抗炎抗衰功效的增效作用

为研究嗜热栖热菌发酵的蚕丝丝肽在皮肤抗炎抗衰功效上的增效作用,以脂多糖(LPS)诱导的角质形成细胞(HaCaT细胞)和双氧水(H2O2)诱导的成纤维细胞(HDF细胞)为研究模型,通过比色法、酶联免疫吸附(ELISA)等方法检测蚕丝丝肽、嗜热栖热菌发酵液和蚕丝丝肽发酵液对细胞活力、炎症因子白介素1β(IL-1β)和白介素6(IL-6)的含量、屏障保湿相关蛋白水通道蛋白3(AQP3)和丝聚蛋白(FLG)的含量、衰老相关标志物超氧化物歧化酶(SOD)、晚期糖基化终产物(AGEs)和人1型胶原蛋白(Col-1)的含量变化的影响。结果表明,蚕丝丝肽发酵液能够显著降低IL-1β,IL-6,AGEs含量,显著促进FLG,AQP3,SOD和Col-1表达,且相较于蚕丝丝肽能更显著抑制IL-6和AGEs表达,更显著促进HDF细胞迁移和SOD合成,而相较于嗜热栖热菌发酵液能更显著降低IL-1β,IL-6和AGEs表达,更显著促进AQP3表达、HDF细胞迁移和SOD的合成,即认为蚕丝丝肽发酵液相较于单一的蚕丝丝肽和嗜热栖热菌发酵液具备抗炎、屏障保湿及抗衰功效的增效作用。

一株嗜高温菌产甘油的特性研究及其发酵条件优化

目的:通过筛选一株高产甘油细菌,为使用细菌生产甘油提供科学依据。方法:以黑松的根系土壤为样本,通过富集培养、分离纯化与耐高温试验,筛选获得一株嗜高温菌株,对其进行菌株鉴定、形态学观察、生理生化鉴定、生长曲线测定以及单因素轮换法发酵条件初步优化。结果:结合透射电镜观察及16S rDNA序列分析,鉴定该菌株为嗜热嗜气解硫胺素芽孢杆菌(Aneurinibacillus thermoaerophilus);生长曲线显示,在0~6 h为生长延迟期、6~21 h为对数生长期;生理生化鉴定,确定其有较优甘油生产功能,其最佳发酵条件为pH 7.0、2%葡萄糖、15‰盐度、6%接种量、温度50℃。结论:该菌株产甘油发酵条件较酵母等真菌具有更高效率。

嗜热菌——工业用酶的新来源

综述了嗜热菌和极端嗜热菌产生的热稳定性的淀粉酶、纤维素酶、环糊精酶、木聚糖酶、几丁质酶、葡萄糖异构酶、蛋白酶等的研究进展及其在食品、化工、环保等方面的应用前景。

极端嗜热厌氧纤维素菌的分离鉴定、系统发育分析及其酶学性质的研究

从云南高温温泉、油井等热源地区采集的大量样品中,获得了一株特殊的极端嗜热厌氧纤维素分解菌B2.分离菌株直杆,革兰氏阴性(G-),未观察到孢子,细胞单个或成对出现.菌体大小为0.4μm×(2-4)μm,严格厌氧,生长温度范围50-70℃,最适生长温度65℃.pH范围4-8,最适pH 7.0.在纤维素粉琼脂上菌落直径2-4 mm,乳白色.分离菌株能利用纤维二糖、葡萄糖、蔗糖、松子糖、淀粉、覃糖等作为碳源,分离菌株还可利用纤维素滤纸、纤维素粉、微晶纤维素、纤维素粉MN300和甘蔗渣、水稻秸杆.发酵纤维素产生乙醇、乙酸.在菌株B2的纤维素酶系中,C1酶、Cx酶和β-葡萄糖苷酶的最适温度分别为80℃、80℃和70℃,其比值为1:9:10,同时发现Cx酶具有较高的热稳定性.部分长度的16S rDNA序列分析表明,分离菌株B2与Thermoanaerobacter ethanalicus具有99.8％相似性.分离菌株B2为Thermoanaerobacter属.

微曝气条件下S-TE剩余污泥溶解性研究

研究了微曝气、不同温度条件下S-TE预处理对剩余污泥溶解和各种化学组分变化的影响.结果表明,S-TE污泥溶解存在2种反应(酶催化反应和热解反应)和2个过程:嗜热菌胞外酶(主要为蛋白酶和淀粉酶)首先解聚污泥胶团,进而溶解细菌的细胞壁,水解胞内有机物质.接种嗜热菌Bacillus stearothermophilussp.AT06-1比不接种促进了污泥悬浮固体的溶解,接种条件下最适宜的溶解温度为65℃,此温度下,污泥VSS和TSS溶解率相对于不接种试验提高程度最大,2 d时VSS、TSS溶解率分别达到34.09%和24.16%,比不接种试验同期分别提高了7.57%和6.87%;微曝气条件下SCOD和VFA得到累积,最大累积量达到4 531 mg/L和2 319 mg/L,有利于厌氧消化;此时蛋白酶活性提高也最大.污泥溶解产生的蛋白质被蛋白酶水解,蛋白质浓度先升高后降低.

接种高温菌剂的生活垃圾好氧堆肥处理

接种适用于 70～ 80℃高温环境的高效微生物菌剂 ,进行中试规模的城市生活垃圾高温好氧堆肥处理试验研究 ,为上海市某区 50 0t·d- 1生活垃圾的产业化处理处置提供技术路线 .研究表明 ,接种高温菌剂的堆肥初始升温速度快 ,前 8h温度升高 3 7℃ ,而对照组前 13h堆肥温度仅升高 5℃ ;接种堆肥在前 3d高温期温度达到 80～ 85℃ ,有机物去除质量分数 19.2 % (前 3d) ,第 3d好气性异养细菌仍保持在 10 10 数量级 ;而对照组前 3d高温期的温度变化范围为 65～ 70℃ ,有机物去除质量分数为 11.9% (前 3d) ,第 3d好气性异养细菌降为 10 9数量级 ;接种堆肥较对照组发酵周期明显缩短 ,一次发酵缩短 3～ 4d ,二次发酵缩短了 6～ 7d .表明高温菌剂的投加 ,增强了微生物生态系统的功能 。