微生物学报  2022, Vol. 62 Issue (2): 661-671   DOI: 10.13343/j.cnki.wsxb.20210294.
http://dx.doi.org/10.13343/j.cnki.wsxb.20210294
中国科学院微生物研究所,中国微生物学会,中国菌物学会
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文章信息

李方玲, 张雅坤, 梁立宝, 王小通, 杜显元, 王磊. 2022
LI Fangling, ZHANG Yakun, LIANG Libao, WANG Xiaotong, DU Xianyuan, WANG Lei.
石油污染环境中固氮和寡氮营养细菌的分离鉴定及其特性
Identification and characteration of nitrogen-fixing bacteria and oligotrophic-nitrogen bacteria from the polluted petroleum
微生物学报, 62(2): 661-671
Acta Microbiologica Sinica, 62(2): 661-671

文章历史

收稿日期:2021-05-29
修回日期:2021-06-25
网络出版日期:2021-07-16
石油污染环境中固氮和寡氮营养细菌的分离鉴定及其特性
李方玲1,2 #, 张雅坤1 #, 梁立宝3 , 王小通4 , 杜显元5 , 王磊1     
1. 中国农业大学生物学院微生物学与免疫学系, 农业生物技术国家重点实验室, 北京 100193;
2. 北京华科仪科技股份有限公司, 北京 100076;
3. 新疆油田公司百口泉采油厂注输联合站, 新疆 克拉玛依 834000;
4. 中国科学院微生物研究所, 北京 100101;
5. 石油石化污染物控制与处理国家重点实验室, 北京 102206
摘要[背景] 石油污染治理中的生物修复因无二次污染、处理成本低等优点受到人们的广泛关注,但由于石油烃向环境中大量输入,导致环境中氮源的相对不足成为制约生物修复效率的关键因素之一,因此筛选能够适应寡氮环境的微生物具有重要的生态意义。[目的] 从辽河油田油藏水中筛选在不添加氮源培养基中生长的微生物,为石油污染环境生物修复提供候选菌株。[方法] 利用改良无氮培养基分离菌株,根据16S rRNA基因序列同源性鉴定菌株,并对其进行固氮酶活性分析、固氮基因和石油降解基因扩增。[结果] 筛选得到21株菌,分属于16个不同的属,其中假单胞菌属所占比例最高(23.8%)。固氮酶活性分析结果表明,8株细菌可检测到乙炔还原活性,从3株菌株中扩增到固氮基因nifH,其余13株细菌被鉴定为寡氮营养菌(oligotrophic-nitrogen bacteria)。对21株菌株的石油降解相关基因进行扩增,发现5株菌株基因组中具有烷烃单加氧酶基因alkB或细胞色素P450基因。[结论] 本研究从辽河油田油藏水中分离到的细菌适应寡氮环境,具备降解石油潜能,丰富了石油污染地区的微生物多样性,为生物修复提供菌种基础。
关键词石油污染    固氮菌    寡氮营养菌    石油降解基因    
Identification and characteration of nitrogen-fixing bacteria and oligotrophic-nitrogen bacteria from the polluted petroleum
LI Fangling1,2 #, ZHANG Yakun1 #, LIANG Libao3 , WANG Xiaotong4 , DU Xianyuan5 , WANG Lei1     
1. State Key Laboratory of Agrobiotechnology, Department of Microbiology and Immunology, College of Biological Sciences, China Agricultural University, Beijing 100193, China;
2. HKY Technology Company Limited, Beijing 100076, China;
3. Xinjiang Petroleum Company Baikouquan Oil Production Plant Injection and Transportation Joint Station, Karamay 834000, Xinjiang, China;
4. Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China;
5. State Key Laboratory of Petroleum and Petrochemical Pollutants Control and Treatment, Beijing 102206, China
Abstract: Bioremediation in petroleum pollution has attracted wide attention due to its advantages including no secondary pollution and low cost. However, due to the large input of petroleum hydrocarbons into the environment, the relative shortage of nitrogen sources in the environment has become one of the key factors that restricted the efficiency of bioremediation. Therefore, screening microorganisms that can grow in the oligotrophic-nitrogen environments has important ecological significance. [Objective] To screen microorganisms that can grow on nitrogen-free conditions from the Liaohe Oilfield reservoir, and to provide candidate strains for the bioremediation of petroleum- contaminated environments. [Methods] The strains were isolated using modified nitrogen-free medium, followed by the analysis of 16S rRNA gene sequence and nitrogenase activity, and amplication of nitrogen fixation genes and petroleum degradation genes. [Results] 21 microorganisms were screened, belonging to 16 different genera, among which Pseudomonas accounted for the highest proportion. The analysis of nitrogenase activity showed that 8 microorganisms could detect acetylene reduction activity, 3 microorganisms successfully amplified the nitrogen-fixing gene nifH, and the remaining 13 microorganisms defined them as oligotrophic-nitrogen bacteria. Amplification of petroleum degradation-related genes in these 21 strains revealed that 5 strains have alkB monooxygenase genes or cytochrome P450 genes in their genomes. [Conclusion] The bacteria isolated from the reservoir water of the Liaohe Oilfield in this study can adapt to the oligo-nitrogen environment, coupled with the potential to degrade oil. This study enrichs the microbial diversity in oil-contaminated areas and provide bacterial foundation for microbial remediation.
Keywords: petroleum pollution    nitrogen-fixing bacteria    oligotrophic-nitrogen bacteria    petroleum degrading genes    

石油是由各种有机体埋藏于地下形成的深褐色液体,以原油、天然气及天然焦油等多种形式存在[1]。石油成分较为复杂,包括各种直链烷烃、支链烷烃、环烷烃、单芳烃和多环芳烃。在某些化合物的结构中会发现大量硫、氧和氮元素,而磷、钒和镍等重金属则很少见[2]。目前,造成石油污染的来源主要包括两种方式,一种是自然方式,如火山爆发,另一种是人为导致,如石油在开采和运输过程中导致的泄露[3]。大多数的石油是通过海上运输到世界各地,发生石油泄露会对当地的海洋环境造成巨大危害。比如墨西哥湾的“深水地平线”溢油事件是最严重的漏油事故之一,不仅造成了巨大损失,还严重破坏了周围环境[4]。除此之外,当石油泄露进入土壤后,会破坏土壤理化性质,影响微生物群落结构[5]

从20世纪开始,生物修复石油污染就被认为是一个低成本、环境友好的方法。而微生物修复技术效果较好,应用也最为广泛。微生物修复是指在一系列加氧酶的作用下,通过氧化作用将环境中的有毒污染物转化为无毒化合物[67]。在此修复过程中,微生物起到至关重要的作用。

近年来对石油污染环境中微生物的研究主要集中于石油降解菌的筛选及构建[810]。Kiamarsi等利用以原油为唯一碳源的基础培养基从原油污染土样中分离出食树脂假单胞菌(Pseudomonas resinovorans)、极光植物杆菌(Plantibacter auratus)、枯草芽孢杆菌(Bacillus subtilis)、巴斯德葡萄球菌(Staphylococcus pasteuri)和萎缩芽孢杆菌(Bacillus atrophaeus),这些菌株对脂肪族化合物和芳香族化合物均有不同程度的降解[11]。沈聪等从宁夏盐池原油污染土壤中筛选得到25株石油降解菌,土壤修复实验表明,复合菌剂的修复效果要高于单一菌剂[12]

在石油污染环境中,由于石油含量骤增,引起环境中氮含量相对缺乏,导致氮素成为限制微生物生长代谢及降解效率的主要因素之一[13]。而生物固氮可能是原位生物降解石油过程中一个强有力的选择特征。在石油污染环境中,固氮微生物群落数量显著增加,这是促进烃类降解及对贫氮压力响应的结果[14]。Al-Mailem等在科威特南部和北部沿海的高盐度水域和土壤中分离出2株能够固氮的嗜盐石油降解菌,Marinobacter depositedarumM. flavimaris。这2种菌株在不添加任何氮源的情况下,仍具备原油降解能力[15]。除此之外,有文献报道从石油污染环境中分离到固氮菌,如固氮菌属(Azotobacter)、假单胞菌属(Pseudomonas)、固氮螺菌属(Azospirillum)、水螺菌属(Aquaspirillum)和迪茨氏菌属(Dietzia)细菌[1618]。Karthikeyan等基于宏基因组指导的分离法,获得了优势原油降解新物种,暂命名为马孔多固氮单胞菌(Macondimonas diazotrophica)。序列分析表明,在世界各地沿海海洋生态系统的油污沉积物中马孔多固氮单胞菌的数量丰富,约占总群落的30%,而在原始沉积物或海水中几乎不存在。对马孔多固氮单胞菌基因组分析,发现存在固氮和烷烃降解基因以及生物表面活性剂合成基因等,说明了其在典型的氮限制、油污环境中的生长优势[19]。虽然向石油污染环境中外源添加氮肥可促进石油烃降解,但过量施加氮肥,不但会引起环境中硝酸盐含量增加,造成二次污染,还增加了修复成本[20]。同时,在生物修复过程中提供氮源的常见做法可能会导致土著烃类降解菌多样性的变化[19],进而影响烷烃降解效率。因此,筛选适应寡氮环境的微生物可以克服石油污染环境中养分缺乏问题,进而为生物修复提供潜在的特征性菌种资源。

本文从辽河油田油藏水中筛选可在改良无氮培养基中生长的菌株,通过16S rRNA基因序列同源性鉴定菌株,利用固氮基因扩增和固氮酶活性分析确定固氮微生物,并对其进行石油降解相关基因扩增及寡氮适应性分析,以期为开发生物修复的复合菌剂提供菌种资源。

1 材料与方法 1.1 土壤样品

油藏水样品取自我国辽河油田附近(41°07′49.40″ N,122°05′0.24″ E)。

1.2 培养基 1.2.1 LB培养基

NaCl 10 g,胰蛋白胨10 g,酵母提取物5 g,琼脂粉15 g,水1 L,pH 7.0。

1.2.2 改良无氮培养基

K2HPO4 1 g,FeSO4·7H2O 0.05 g,无水CaCl2 0.1 g,MgSO4·7H2O 0.2 g,Na2MoO4·2H2O 0.001 g,葡萄糖10 g,琼脂粉15 g,水1 L,pH 7.0。

1.2.3 固氮酶活测定培养基

A液:NaCl 2 g,葡萄糖40 g,柠檬酸铁36 mg,MgSO4·7H2O 0.2 g,Na2MoO4·2H2O 7.6 mg,定容至900 mL;B液:Na2HPO4·12H2O 9.84 g,KH2PO4 1.7 g,定容至100 mL。分别灭菌后混合。

1.2.4 GMCY培养基

葡萄糖10 g,K2HPO4 1 g,MgSO4·7H2O 0.2 g,NaMoO4·2H2O 0.001 g,CaCl2·2H2O 0.1 g,FeSO4·7H2O 0.05 g,酵母提取物0.5 g,酸水解酪蛋白0.5 g,麦芽粉0.5 g,琼脂粉15 g,水1 L,pH 7.0。

1.3 实验试剂

细菌全基因组DNA提取试剂盒购于北京欣汇天科技有限公司,引物购于北京六合华大基因科技有限公司,其他常规试剂购于北京今日经典科技有限公司。

1.4 筛选可在无氮培养基中生长的菌株

取1 mL油藏水样品加至9 mL无菌水中,充分混匀后继续稀释,最终获得10–2,10–3和10–4共3个稀释度,通过混菌法和涂布法分离可在无氮培养基中生长的菌株。混菌法是将1 mL样品稀释液添加到冷却至55 ℃左右的改良无氮培养基中,混匀后倒入培养皿中,30 ℃培养。用涂布法将0.1 mL样品稀释液涂布于改良无氮培养基中,30 ℃培养,培养3–7 d。依据形态、大小和颜色,挑取不同的单菌落,分别在LB和GMCY培养基平板上划线纯化并编号,30 ℃培养,培养3–7 d。

1.5 分离菌株的分子生物学鉴定

以菌体作为DNA模板,利用16S rRNA基因通用引物27F (5′-GAGAGTTTGATCCTGG CTCAG-3′)和1492R (5′-TACGGCTACCTTGT TACGAC-3′)[21]扩增16S rRNA基因片段,经琼脂糖凝胶检测后,将大小为1.5 kb的产物送至北京六合华大基因科技有限公司测序。利用SeqMan拼接序列后,使用EZbiocloud数据库(http://www.ezbiocloud.net/)进行16S rRNA基因序列比对。用MEGA 7软件构建系统发育树,采用neighbor-joining法确定分离菌株的系统发育地位[22]

1.6 固氮酶活性检测

将单菌落接种到5 mL最适生长液体培养基中,30 ℃培养至对数生长期,10 000 r/min离心4 min收集菌体,无菌水清洗3次,并悬浮于固氮酶活性测定液体培养基中,检测OD600值。将上述菌悬液加到冷却至55 ℃左右的固氮酶活性测定半固体培养基中,使最终OD600值为0.2。最后取10 mL上述混合物,加入25 mL厌氧管中,封口膜密封后,30 ℃培养,待其呈现明显生长时,使用注射器向每管内注入2 mL乙炔,胶塞密闭后继续培养;培养24–48 h后,使用微量进样器抽出100 μL气体注入气相色谱仪中,记录乙烯峰出现的保留时间以及峰面积。通过与标准样品对照,最终计算出厌氧管内乙烯的含量。参数设置为:载气:N2;助燃气:H2;柱箱初始温度:70 ℃。乙烯含量(nmoL)的计算按照公式(1)进行。

公式(1)
1.7 固氮基因和石油降解基因的扩增

以基因组DNA为模板,扩增固氮酶基因(nifH)、烷烃单加氧酶基因(alkB)、细胞色素酶基因(P450)、苯酚羟化酶基因(phe)、儿茶酚-2, 3-双加氧酶基因(xylE)和黄素结合单加氧酶基因(almA)。引物序列如表 1所示。固氮基因nifH和烷烃单加氧酶基因alkB基因扩增的反应条件为94 ℃ 4 min;94 ℃ 30 s,57 ℃ 30 s,72 ℃ 20 s,35个循环,72 ℃ 10 min。其他4种基因PCR反应的退火温度为53 ℃,32个循环。

表 1. 引物序列 Table 1. Primers
Genes Sequences (5′→3′)
nifH[23] F: TGCGAYCCSAARGCBGACTC
R: ATSGCCATCATYTCRCCGGA
alkB[24] F: AAYACNGCNCAYGARCTNGGNCAYAA
R: GCRTGRTGRTCNGARTGNCGYTG
P450[24] F: TGTCGGTTGAAATGTTCATYGCNMTGGA
R: TGCAGTTCGGCAAGGCGGTTDCCSRYRC
phe[25] F: AGGCATCAAGATCACCGACTG
R: CGCCAGAACCATTTATCGATC
xylE[26] F: AGGTATGGCGGCTGTGCGTTTC
R: TTCGTTGAGAATGCGGTCGTGG
almA[27] F: GGNGGNACNTGGGAYCTNTT
R: ATRTCNGCYTTNAGNGTCC

2 结果与分析 2.1 分离菌株16S rRNA基因序列和系统发育学分析

本研究共分离得到21株细菌,对其进行16S rRNA基因序列测定,将测序结果在EZbiocloud数据库中进行序列比对,鉴定结果见表 2。从表中可知,21株细菌分属于16个不同的属,分别是SiccirubricoccusBrevibacillusMethyloversatilisBrucellaAgrobacteriumVerticiellaPannonibacterBoseaMethylorubrumPhaeospirillumKlebsiellaBacillusAcinetobacterNeorhizobiumPseudomonasNovosphingobium。其中假单胞菌属所占比例最高(23.8%),其次是土壤农杆菌属(9.5%)。

表 2. 21株菌株的种属鉴定表 Table 2. Identification of the 21 bacterial isolates
Isolates The most similar strains based on 16S rRNA Similarity/%
31-1 Acinetobacter junii 98.7
19-6 Agrobacterium arsenijevicii 99.0
28-2 Agrobacterium larrymoorei 99.6
48-2 Bacillus tequilensis 98.6
1-4 Brevibacillus agri 99.2
38-4 Bosea eneae 98.0
5-1 Brucella intermedia 100.0
49-1 Klebsiella michiganensis 99.9
2-1 Methyloversatilis discipulorum 99.0
52-1 Methylorubrum rhodesianum 99.8
16-3 Neorhizobium alkalisoli 99.0
1-1 Novosphingobium meiothermophilum 98.0
38-1 Pannonibacter phragmitetus 98.4
64-1 Phaeospirillum chandramohanii 92.0
5-3 Pseudomonas oleovorans subsp. lubricantis 99.7
19-2 Pseudomonas chengduensis 98.9
19-10 Pseudomonas aeruginosa 98.4
40-1 Pseudomonas oleovorans subsp. oleovorans 99.4
45-5 Pseudomonas balearica 99.7
1-3 Siccirubricoccus sp. 96.7
23-5 Verticiella sediminum 98.7

2.2 固氮基因和固氮酶活性分析

编码固氮酶蛋白的nifH基因是系统进化中最古老和保守的基因之一,因此通常选取nifH基因作为检测微生物是否具备固氮特性的生物标识[28]。利用通用引物(PolR-PolF)扩增这21株菌的固氮基因nifH。结果从3株细菌中扩增到nifH,它们分别是Pannonibacter sp. 38-1、Klebsiella sp. 49-1和Phaeospirillum sp. 64-1,nifH基因系统发育分析树见图 1

图 1 nifH基因系统发育树 Figure 1 Phylogenetic tree of isolates based on nifH gene. Node values represent percent bootstrap confidence derived from 1 000 replicates. Bar 0.1 at the bottom is the sequence divergence. The GenBank accession numbers of the indicated sequences are shown in the parentheses.

此外,乙炔还原法也常用来测定微生物的固氮酶活性,可初步检测固氮酶活性及活性高低。本研究对分离出的21株菌的乙炔还原法测定结果表明,8株微生物可检测到乙炔还原酶活性(图 2)。其中Methyloversatilis sp. 2-1、Neorhizobium sp. 16-3、Agrobacterium sp. 19-6、Bosea sp. 38-4和Pseudomonas sp. 45-5虽然未扩增出固氮基因nifH,但能检测到乙炔还原酶活性。

图 2 不同菌株固氮酶活性测定 Figure 2 Determination of nitrogenase activity of different strains. The results are from three biological replicates, and the error bars in the figure represent the SD value.

2.3 寡氮营养菌对氮源利用能力

无氮培养基分离菌株的结果表明,只有少部分菌株具有固氮菌特征,大部分菌株并没有明确的固氮酶基因或乙炔还原活性,但其可在贫氮条件下生长,因而将其命名为寡氮营养菌。有研究表明,石油污染环境中的氮含量约为0.8 mg/L[29],而一般培养基中的氮含量为1.5 g/L。基于石油降解能力及不同种属分析,选取实验室部分寡氮营养菌,观察这些菌株在添加不同浓度硫酸铵培养基中的生长状况,进而探究寡氮营养菌对氮源的利用能力。如表 3所示,在不添加氮源的固体培养基中,选取的9株寡氮营养菌均可生长,结果表明这些菌株可适应寡氮环境,能够高效利用环境中的痕量铵。随着铵浓度增加,大多数寡氮营养菌生长态势更好,这一结果说明这类微生物并非专性寡氮营养微生物,因而具有更宽泛的养分适应能力,为后续开发复合菌剂增强生物修复效果奠定基础。

表 3. 不同铵浓度下菌株生长情况 Table 3. Growth of strains under different ammonium concentrations (mg/L)
Samples 5 000 1 500 1.6 0.8 0.4 0.2 0
Pseudomonas sp. A4 + +++ + + + + +
Pseudomonas sp. C7 ++ +++ ++ ++ ++ ++ +
Pseudomonas sp. D11 + ++ + + + + +
Pseudomonas sp. E9 ++ +++ ++ ++ ++ ++ +
Pseudomonas sp. G26 + + + + + + +
Pseudomonas sp. G27 + + + + + + +
Sphingobium sp. F3 ++ +++ ++ ++ ++ ++ +
Sphingobium sp. F11 ++ +++ ++ ++ ++ ++ +
Pandoraea sp. E5 ++ +++ ++ ++ ++ ++ +
+: poor growth; ++: good growth; +++: better growth.

2.4 石油降解相关基因的测定

对从石油污染环境中分离的21株菌进行石油降解相关基因扩增,包括烷烃单加氧酶基因alkB、细胞色素P450基因P450、苯酚羟化酶基因phe、儿茶酚-2, 3-双加氧酶基因xylE和黄素结合单加氧酶基因almAalkBP450主要负责降解短中碳链的烷烃,但两者的作用底物并不完全重叠,almA主要负责催化长链烷烃,phexylE主要负责降解芳香烃苯酚。结果从菌株Novosphingobium sp. 1-1、Verticiella sp. 23-5、Acinetobacter sp. 31-1和Pannonibacter sp. 38-1扩增出alkB基因,菌株Siccirubricoccus sp. 1-3和菌株Acinetobacter sp. 31-1扩增出P450基因,上述菌株的石油降解相关基因系统发育树见图 3。以上结果说明从石油污染环境中分离出的菌株具备降解石油的潜能。

图 3 alkB基因和P450基因系统发育树 Figure 3 Phylogenetic tree of isolates based on alkB gene and P450 gene. A: alkB gene; B: P450 gene. Node values represent percent bootstrap confidence derived from 1 000 replicates. Bar 0.1 and 0.05 at the bottom are the sequence divergence. The GenBank accession numbers of the indicated sequences are shown in the parentheses.

3 讨论

微生物对生长环境高度敏感,生物修复会受到多种因素的影响。主要包括以下几种:污染物的生物可利用性[3031]、微生物自身[32]及环境因素(温度、pH、营养物质[13, 3334])。石油污染环境中,碳含量急剧增加,氮含量相对较少,这种严重失衡的碳氮比,导致氮素成为影响生物修复的重要因素之一,在此环境中也会“进化”出一些对寡氮适应的微生物。基于此,本研究从辽河油田油藏水中筛选出可在改良无氮培养基中生长的微生物,共21株,包括8株固氮菌和13株寡氮营养菌。

本研究分离获得的21株菌中,假单胞菌属和农杆菌属所占比例较高,而在实验室前期菌株分离工作中,陈琳[26]利用改良无氮培养基从盘锦土壤中分离获得50株菌株,其中假单胞菌属(Pseudomonas)和类芽孢杆菌属(Paenibacillus)为优势属种,而张雅茜[35]从新疆克拉玛依油藏水中分离得到6个属的10株菌可在不添加氮源的培养基中生长,主要属种为耐盐菌属(Salinicola)和副球菌属(Paracoccus)。在这3种不同的石油污染环境中,均分离出假单胞菌属菌株。基于假单胞菌属在环境中分布范围广且对环境的适应性强等特点,因此在实验室分离工作中检出率很高。而本研究分离得到的SiccirubricoccusBrevibacillusMethyloversatilisBrucellaAgrobacteriumVerticiellaPannonibacterBoseaMethylorubrumPhaeospirillum等10个属种在实验室前期分离菌种工作中并未涉及,说明不同环境中的微生物具有一定的特异性,本研究丰富了石油污染环境中贫氮适应性微生物的多样性,为后续相关筛选工作的开展奠定了菌种资源基础。

据报道,AgrobacteriumNeorhizobiumPseudomonasKlebsiella属中的部分菌株具备固氮能力[3639]。本研究中,Agrobacterium sp. 19-6虽然检测到很高的乙炔还原酶活性,但利用通用引物(PolR-PolF)并未扩增出nifH基因,表明该属的固氮基因nifH具有一定的多样性。除此之外,Pannonibacter属之前并未有关于固氮能力的报道,但是在本研究中,Pannonibacter sp. 38-1不仅检测到乙炔还原酶活性,还成功扩增出nifH固氮基因,而系统发育分析结果表明,该菌株的nifH基因序列与环境中一些未培养菌株相似性最高,这一结果表明该属可能具有固氮能力。

石油烃降解相关基因扩增结果表明,5株菌具备石油降解潜能,分别为新鞘氨醇杆菌属Novosphingobium sp. 1-1、Verticiella sp. 23-5、不动杆菌属Acinetobacter sp. 31-1、Pannonibacter sp. 38-1和Siccirubricoccus sp. 1-3。Chaudhary等在石油污染土壤中分离到2株可降解石油的新鞘氨醇杆菌属菌株[40],不动杆菌属和Pannonibacter属也有报道参与原油降解[4142]。而VerticiellaSiccirubricoccus却未有文献报道具有降解石油能力,系统发育树中Siccirubricoccus属的P450基因序列与未培养菌株的功能基因同源性最高,因此后续可进一步确定其功能及特征。

基于石油污染环境的寡氮特性,本研究着重探究可在不添加氮源固体培养基中生长的微生物多样性,并通过固氮酶活性测定,确定了固氮菌和寡氮营养菌。同时,探究了菌株对石油的降解潜能和寡氮适应性。从石油污染环境中获得的固氮菌在耐受石油烃方面具有独特的优势,且是贫氮环境中氮源补充的有利候选者。固氮菌通常情况下固定的氮仅用于满足自身所需,不会主动向环境分泌[43],而寡氮营养型微生物对氮的低需求及其拥有的石油降解能力,无疑是固氮菌的优选搭档。复杂的微生物群落中,养分交流的协作共赢是最为高效的社会性行为[44],因地制宜地开发功能性菌株资源,明确互养机制,构建互生模式,可增强生物修复的效果,将为未来开发生物修复的合成生物学菌群奠定基础。

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