Diversity of soil bacteria and fungi communities in artificial forests of the sandy-hilly region of Northwest China

Soil erosion is a serious issue in the sandy-hilly region of Shanxi Province,Northwest China.There has been gradual improvement due to vegetation restoration,but soil microbial community characteristics in different vegetation plantation types have not been widely investigated.To address this,we analyzed soil bacterial and fungal community structures,diversity,and microbial and soil environmental factors in Caragana korshinskii Kom.,Populus tomentosa Carr.,Populus simonii Carr.,Salix matsudana Koidz,and Pinus tabulaeformis Carr.forests.There were no significant differences in the dominant bacterial community compositions among the five forest types.The alpha diversity of the bacteria and fungi communities showed that ACE(abundance-based coverage estimator),Chao1,and Shannon indices in C.korshinskii forest were significantly higher than those in the other four forest types(P<0.05).Soil organic matter,total nitrogen,and urease had a greater impact on bacterial community composition,while total nitrogen,β-glucosidase,and urease had a greater impact on fungal community composition.The relative abundance of beneficial and pathogenic microorganisms was similar across all forest types.Based on microbial community composition,diversity,and soil fertility,we ranked the plantations from most to least suitable as follows:C.korshinskii,S.matsudana,P.tabulaeformis,P.tomentosa,and P.simonii.

Resistance of Microbial Community of Artemisia annua L.to Pathogenic Fungi

[Objectives]This paper was to figure out whether the dominant bacterial community has the role and effect of bacterial community and its defense mechanism against potential pathogenic fungi in Artemisia annua,and thus establish a systematic model of bacteria-fungus-plant.[Methods]Fifty-eight strains of bacteria and one strain of pathogenic fungi,Globisporangium ultimatum,were used for the experiments.These 58 bacterial strains were assembled into a bacterial community,and the bacteria with abundance in the top 1%were reassembled into a dominant bacterial community as measured by 16S rDNA.[Results]The growth of A.annua seedlings inoculated with bacterial communities and pathogenic fungi or dominant bacterial communities and pathogenic fungi was significantly better than that of A.annua seedlings inoculated with pathogenic fungi during in vitro confrontation,which was evident in both enzymatic and non-enzymatic antioxidant assays.[Conclusions]The results suggest that the dominant bacterial community has a crucial role as a representative core microbial community of synthetic bacterial community,which can protect plants by interfering with the growth of phytopathogenic fungi mediated by chemical signals,and can be used as the main synthetic community of biocides to achieve the effect of biocontrol.

Effect of Arbuscular Mycorrhizal Fungi and Their Partner Bacteria on the Growth of Sesame Plants and the Concentration of Sesamin in the Seeds

Arbuscular mycorrhizal fungi (AMF) can stimulate the plant growth. Pseudomonas sp. (KCIGC01) NBRC109613 isolated from the spores of Glomus clarum IK97, an AMF, is reported to support the plant growth and development as partner bacteria (PB) for AMF REF _Ref399417929 \r \h \* MERGEFORMAT [1]. In order to investigate the effect of G. clarum IK97 and Pseudomonas sp. (KCIGC01) NBRC109613 on the secondary metabolites, these microorganisms were inoculated to sesame plants. The inoculation of these microorganisms stimulated the growth of sesame. The rate of sesame root colonization in G. clarum IK97 + Pseudomonas sp. (KCIGC01) NBRC109613 inoculated plants (66.4% ± 4.4%) was higher than that in G. clarum IK97 alone inoculated plants (39.2% ± 5.8%). Furthermore, the content of sesamin in sesame seeds was increased by the inoculation of these microorganisms. In particular, the content of sesamin in the treatment inoculated with G. clarum IK97 and Pseudomonas sp. (KCIGC01) NBRC-109613 was 11.4 ± 1.5 mg/g seed. The results suggest that AMF and their partner bacteria can stimulate the growth and development of sesame plants and increase the content of sesamin in the seeds.

Straw bio-degradation by acidogenic bacteria and composite fungi

A composite microbial system, including a strain of Candida tropicalis(W3), a strain of Lactobacillus plantarm(WY3) and three strains of basidiomycete pL104, pL113 and C33, was chosen to degrade corn straw. The final pH was acid owing to the inoculation of acidogenic bacteria, and under this condition the composite fungi system could produce complex enzyme to destroy the compact structure of corn straw. The experimental results showed that the biomass of composite fungi could reach up to maximum when the pH value was 4.5. Through the bio-degradation by combining acidogenic bacteria with the composite fungi system, the cellulose, hemi-cellulose and lignin degradation rates of corn straw powder were 26.36%, 43.30% and 26.96%, respectively. And the gross crude protein content increased 60.41%. This study provided the evidence for the feasibility of developing a composite microbial system with high capability of degrading straw lignocelluloses in order to make reasonable use of straw resource and protect rural eco-environment.

BIOLOGICAL NITROGEN REMOVAL FROM WASTEWATER BY DENITRIFICATION OF MIX-CULTURING FUNGI AND BACTERIA

Denitrification has been long thought to be a unique characteristic of prokaryotes, but in recent years, several filamentous fungi and yeasts were found to exhibit denitrifying activities. This paper deals with the examination of denitrification capabilities by mix-cultures of the fungus (Fusarium oxysporum) and the bacterium (Pseudomonas stutzeri TR2) in combination with a specific medium and using a synthetic wastewater of defined quality. The results revealed that P. stutzeri TR2 has strong and fast denitrifying capabilities under anaerobic conditions, and that co-denitrification of mix-cultures with F. oxysporum and P. stutzeri TR2 was more effective to remove nitrate under limited oxygen conditions. P. stutzeri TR2 was able to remove nitrate completely during cultivation for 12 hr in the specific medium and in mixed culture with F. oxysporum. A rapid N 2 evolution by mixed culture with F. oxysporum and P. stutzeri TR2 was observed in both mixed culture medium and synthetic wastewater. Using synthetic wastewater with a defined composition, about 87% of the nitrate was eliminated to form about 420μmol of N 2 from 1.0mmol of NO-3 by co-denitrification of F. oxysporum and P. stutzeri TR2 after incubation for 6days. In co-cultures of F. oxysporum and P. stutzeri TR2, N2O produced by F. oxysporum was rapidly consumed by P. stutzeri TR2. This indicated that mixed culture of F. oxysporum and P. stutzeri TR2 can be used to remove nitrate and nitrite from wastewater effectively.

Response of arbuscular mycorrhizal fungi and phosphorus solubilizing bacteria to remediation abandoned solid waste of coal mine

Coal is the vital resource of energy in China,but abandoned coal ash and gangue lead to the degradation of vegetation cover and reduce soil quality.Both arbuscular mycorrhizal fungi (AMF) and phosphate solubilizing bacteria (PSB) play a key role in biogeochemical cycle such as soil organic matter decomposition,nutrition release,and energy flow.To improve and reclamation the soil quality and ecological efficiency of the coal mining waste,we investigated the effects of an AMF strain (Glomus mosseae) and a PSB strain (Pantoesstewarti) on phytate mineralization and subsequent transfer to the host plant (Medicago sativa L.) using a two-compartment microcosm with a central 30 mm nylon mesh barrier.The results showed that significantly higher available P (AP),above ground biomass (AGB) and underground biomass (UGB) were in combined inoculation of AMF-PSB than other treatments in root and hyphae compartment.The microbial inoculum of the AMF or PSB had a significant influence on soil acid phosphatase activities (ACP).AMF-PSB enhanced phytate mineralization,improved plant biomass.AP and ACP positively influenced the AGB and UGB.AMF-PSB could be used as bioinoculant to enhance sustainable production of the plant in abandoned solid waste of coal mine.

Uniform categorization of biocommunication in bacteria,fungi and plants

This article describes a coherent biocommunication categorization for the kingdoms of bacteria,fungi and plants. The investigation further shows that,besides biotic sign use in trans-,inter-and intraorganismic communication processes,a common trait is interpretation of abiotic influences as indicators to generate an appropriate adaptive behaviour.Far from being mechanistic interactions,communication processes within organisms and between organisms are sign-mediated interactions.Sign-mediated interactions are the precondition for every cooperation and coordination between at least two biological agents such as cells,tissues,organs and organisms.Signs of biocommunicative processes are chemical molecules in most cases.The signs that are used in a great variety of signaling processes follow syntactic(combinatorial) ,pragmatic(context-dependent) and semantic(contentspecific) rules.These three levels of semiotic rules are helpful tools to investigate communication processes throughout all organismic kingdoms.It is not the aim to present the latest empirical data concerning communication in these three kingdoms but to present a unifying perspective that is able to interconnect transdisciplinary research on bacteria,fungi and plants.

The effect of soil moisture on the response by fungi and bacteria to nitrogen additions for N_(2)O production

In addition to bacteria,the contribution of fungi to nitrous oxide(N_(2)O)production has been recognized but the responses of these two broad and unrelated groups of microorganisms to global environmental changes,atmospheric nitrogen(N)deposition,and precipitation in terms of N_(2)O production are unclear.We studied how these two microbial-mediated N_(2)O production pathways responded to soil moisture conditions and to N addition in an N-limited temperate forest.Soils from a long-term N addition experiment in Changbai Mountain,northeastern China were incubated.Varied concentrations of cycloheximide and streptomycin,both inhibitors of fungal and bacterial activity,were used to determine the contributions of both to N_(2)O production in 66%,98%and 130%water-filled pore spaces(WFPS).The results showed that N_(2)O production decreased significantly with increasing cycloheximide concentration whereas streptomycin was only inhibiting N_(2)O emissions at 98%and 130%WFPS.The bacterial pathway of N_(2)O production in N-addition(Nadd)soil was significantly more dominant than that in untreated(Namb)soil.The difference in the fungal pathway of N_(2)O production between the soil with nitrogen addition and the untreated soil was not significant.Net N_(2)O emissions increased with increasing soil moisture,especially at 130%WFPS,a completely flooded condition.Bacteria dominated carbon dioxide(CO_(2))and N_(2)O emissions in Nadd soil and at 130%WFPS regardless of N status,while fungi dominated CO_(2)and N_(2)O emissions in soil without N addition at 66%and 98%WFPS.The results suggest that flooded soil is an important source of N_(2)O emissions and that bacteria might be better adapted to compete in fertile soils under anoxic conditions.

Isolation and Screening of Silicate Bacteria from Various Habitats for Biological Control of Phytopathogenic Fungi

Silicate solubilizing bacteria (SSB) can play an efficient role in soil by solubilizing insoluble forms of silicates. In addition to this some SSB can also solubilize potassium and phosphates, hence increasing soil fertility and enhancing plant defense mechanisms. A total of 111 bacterial strains were isolated from various habitats of Pakistan and screened for solubilization of silicate, phosphate and potassium on respective media. Out of these, 35 bacterial isolates were capable of solubilizing either silicate, phosphate or potassium. Amongst these 7 bacterial isolates were capable of solubilizing all three minerals tested. The highest silicate (zone diameter 54 mm) and phosphate solubilization (zone diameter 55 mm) was observed for bacterial isolate NR-2 while the highest potassium solubilization was observed for NE-4b (zone diameter 11 mm). Dual culture antagonistic assays were carried out by using these bacterial isolates against four plant pathogenic fungi Magnaporthae grisae, Rhizoctonia solani, Altarnaria alternata and Macrophomina pheasolina. Mean zone of inhibition of these bacterial isolates against the four pathogenic fungi ranged between 4 mm to 39 mm. The largest zone of inhibition against all four bacterial strains was recorded for bacterial isolate NR-2 followed by NE-4b. These strains will be further investigated for their plant growth promoting activities in the future.

Plant growth-promoting properties and anti-fungal activity of endophytic bacterial strains isolated from Thymus altaicus and Salvia deserta in arid lands

Endophytes,as crucial components of plant microbial communities,significantly contribute to enhancing the absorption of nutrients such as nitrogen and phosphorus by their hosts,promote plant growth,and degrade pathogenic fungal mycelia.In this study,an experiment was conducted in August 2022 to explore the growth-promoting potential of endophytic bacterial strains isolated from two medical plant species,Thymus altaicus and Salvia deserta,using a series of screening media.Plant samples of Thymus altaicus and Salvia deserta were collected from Zhaosu County and Habahe County in Xinjiang Uygur Autonomous Region,China,in July 2021.Additionally,the inhibitory effects of endophytic bacterial strains on the four pathogenic fungi(Fusarium oxysporum,Fulvia fulva,Alternaria solani,and Valsa mali)were determined through the plate confrontation method.A total of 80 endophytic bacterial strains were isolated from Thymus altaicus,while a total of 60 endophytic bacterial strains were isolated from Salvia deserta.The endophytic bacterial strains from both Thymus altaicus and Salvia deserta exhibited plant growth-promoting properties.Specifically,the strains of Bacillus sp.TR002,Bacillus sp.TR005,Microbacterium sp.TSB5,and Rhodococcus sp.TR013 demonstrated strong cellulase-producing activity,siderophore-producing activity,phosphate solubilization activity,and nitrogen-fixing activity,respectively.Out of 140 endophytic bacterial strains isolated from Thymus altaicus and Salvia deserta,104 strains displayed anti-fungal activity against Fulvia fulva,Alternaria solani,Fusarium oxysporum,and Valsa mali.Furthermore,the strains of Bacillus sp.TR005,Bacillus sp.TS003,and Bacillus sp.TSB7 exhibited robust inhibition rates against all the four pathogenic fungi.In conclusion,the endophytic bacterial strains from Thymus altaicus and Salvia deserta possess both plant growth-promoting and anti-fungal properties,making them promising candidates for future development as growth-promoting agents and biocontrol tools for plant diseases.

设施西瓜连作土壤生化性质及微生物群落变化

为探索设施连作西瓜土壤微生态环境变化,通过高通量测序对连作组(连作10年设施西瓜土壤)和对照组(连作10年设施西瓜棚外相同土质的露天西瓜土壤)样品进行测序分析,比较2组土壤细菌和真菌的群落结构差异,测定土壤理化性质及酶活性。结果表明,连作组土壤pH、铵态氮、速效钾、微生物量碳、土壤酶活性极显著低于对照,而硝态氮和有效磷极显著高于对照组。连作组土壤中细菌ACE指数和Chaol指数均极显著高于对照组,土壤中真菌ACE指数、Chaol指数、Simpson指数和Shannon指数均低于对照组。土壤微生物优势物种组成改变,连作组土壤细菌变形菌门、芽单胞菌门、绿弯菌门及硝化螺旋菌门相对丰度较对照组分别增加了9.80%、20.83%、21.76%和27.12%(P<0.05),而酸杆菌门和疣微菌门较对照组分别减少了21.7%和26.27%(P<0.05);连作组土壤真菌子囊菌门相对丰度较对照组增加了10.96%(P<0.05),担子菌门和罗兹菌门的相对丰度分别较对照组减少了13.42%和93.77%(P<0.05)。相关性分析显示,优势菌门除Latescibacteria和己科河菌门丰度与所有土壤环境因子相关性均不显著外,其他优势菌群都与所测土壤环境因子(有机质除外)存在密切相关关系,土壤pH、铵态氮、有效磷、速效钾是影响土壤中微生物群落的主要因素,担子菌门和绿弯菌门能够指示土壤微生物量,微生物群落结构的变化对土壤酶活性有较大的影响。综上,设施西瓜连作10年土壤理化性质、酶活性及微生物群落结构皆显著变化,西瓜连作障碍是多种因素综合作用的结果。

秀珍菇病害种类调查和病原菌鉴定

近年来,病害频发对秀珍菇产量和品质产生了严重的影响,对其病原菌的鉴定和特性研究非常重要。此次采集了不同时期的患病秀珍菇样本,通过分离纯化获得病原菌,采用科赫法则、显微特征、ITS或16S rRNA测序等方法进行病原菌鉴定。结果表明,真菌病原菌主要有木霉属、青霉属、链孢霉属、毛霉属和毛壳菌属菌类,引发绿霉病、红粉病等真菌性病害,多发生于秀珍菇营养期。细菌病原菌主要有假单胞菌属、欧文菌属、伯克氏菌属、窄食单胞菌属及噬几丁质菌属菌类,引发黄菇病、枯萎病等细菌性病害,多发生于秀珍菇生殖生长期。

冻融对色季拉山高寒森林土壤微生物群落结构的影响

高寒森林土壤是最脆弱的陆地碳库之一,随着全球气候的变暖,冻融格局受到影响,这将导致土壤微生物群落结构发生变化进而影响土壤微生态过程。以西藏色季拉山不同海拔土壤为研究对象,基于16S rRNA测序技术探究微生物群落结构及多样性对季节性冻融的响应。结果表明:门水平上,冻融现象并未改变土壤细菌和真菌群落的优势菌群,变形菌门(Proteobacteria)、放线菌门(Actinobacteriota)和酸杆菌门(Acidobacteria)为细菌群落的优势菌门,担子菌门(Basidiomycota)和子囊菌门(Ascomycota)为真菌群落的优势菌门;属水平上,冻融前后微生物群落结构和组成差异较大,且细菌群落受冻融影响更剧烈,真菌群落受海拔影响更剧烈;OTU水平上,冻融使各海拔细菌群落和海拔3500 m、4300 m处真菌群落的α-多样性有较大提升,主要受黏粒和粉粒含量的影响;冻融使微生物群落组成在不同海拔间差异增大,且冻融前后的关键驱动因子不同,冻融前主要受碳氮比、速效钾、碳酸盐、土壤含水率、黏粒和粉粒含量的影响,冻融后主要受pH和有效磷的影响;相比于细菌,真菌群落结构的影响因素在海拔间的差异更大。本研究为深入理解气候暖化背景下不同海拔高寒森林土壤微生物对冻融的响应提供重要依据。

新疆甜瓜采后致腐菌及拮抗菌的分离、筛选与鉴定

[目的]对甜瓜采后主要致腐微生物进行分离鉴定,并筛选出防腐效果最佳的拮抗菌株,丰富甜瓜采后保鲜拮抗菌资源。[方法]利用组织块分离法在腐烂的甜瓜果实中分离致腐菌,采用梯度稀释法从甜瓜种植地土壤分离拮抗菌,通过平板对峙法筛选出拮抗作用较强的生防菌,并通过形态学观察、生理生化测定、生物学鉴定确定其种属,测定拮抗菌对菌丝生长及分生孢子萌发的作用,明确拮抗菌对致腐菌的防治效果。[结果]本研究分离出1株主要病原菌CH-3,通过对ITS、tef和tub基因序列进行BLAST比对及系统发育分析,结合菌落形态特征观察,病原菌CH-3鉴定为尖孢镰刀菌。从甜瓜种植地土壤中分离得到67株细菌,通过拮抗试验得到3株抑菌活性很强的拮抗菌,分别为BG-1、BG-2和BG-3,选取抑菌效果更好的BG-2作为供试菌株,结合生理生化测定、菌落和菌体形态特征观察及16S rDNA、gyrB和rpoB基因序列分析结果,明确拮抗菌BG-2为贝莱斯芽孢杆菌。致病性测定结果表明,致腐菌CH-3对甜瓜有致病性,拮抗菌BG-2对甜瓜致腐菌尖孢镰刀菌CH-3孢子萌发、菌丝生长的相对抑制率分别为90.00%、60.11%。[结论]获得1株拮抗效果最佳的拮抗菌BG-2,鉴定为贝莱斯芽孢杆菌,分离到1株甜瓜主要致腐菌CH-3,鉴定为尖孢镰刀菌。贝莱斯芽孢杆菌BG-2对尖孢镰刀菌CH-3有较强的拮抗作用,致腐菌CH-3对甜瓜有致病性,拮抗菌BG-2能有效抑制甜瓜致腐菌尖孢镰刀菌CH-3孢子萌发和菌丝生长,且拮抗菌浓度越高对孢子萌发的抑制效果越好,在甜瓜采后贮藏及生物保鲜中具有潜在的应用价值。

微塑料对土壤微生物群落结构影响及共生网络分析

土壤是微塑料的主要储存库,微塑料进入土壤生态系统后可以形成与周围环境显著不同的“塑料圈”,影响土壤微生物群落结构。通过外源添加微塑料颗粒模拟不同程度的农田土壤微塑料污染,探究微塑料对土壤微生物群落的影响。结果显示,微塑料污染会对土壤中微生物属水平细菌和真菌群落带来极大改变,根际土壤和非根际土壤的微塑料处理高浓度组真菌群落特有属数量显著高于低浓度组(p<0.05),且微塑料污染引起的根际土壤与非根际土壤的细菌群落和真菌群落结构变化均存在较大差异。土壤微生物群落多样性及共生网络分析结果表明,高浓度组微塑料添加显著降低土壤微生物多样性,微塑料对根际土壤微生物的影响大于非根际土壤。研究结果提示土壤真菌群落对微塑料污染的响应程度大于细菌群落,未来土壤微塑料相关研究需要进一步重视根际土壤监测。

短期OTC增温对晋北农牧交错带温性草地土壤微生物的影响

土壤微生物作为参与生物地球化学循环的重要生物类群,对陆地生态系统至关重要,但温度升高如何影响农牧交错带温性草地土壤微生物群落的丰度仍不清楚。本研究依托山西右玉黄土高原草地生态系统定位观测研究站2017年建立的开顶式同化箱(Open-Top chamber,OTC)增温实验平台,处理5年后进行土壤样品的采集,测定土壤真菌和细菌的丰度以及土壤微生物生物量碳(Microbial biomass carbon,MBC)和氮(Microbial biomass nitrogen,MBN)含量等指标,探讨农牧交错带温性草地土壤微生物对不同增温处理的响应。结果表明:增温显著降低土壤真菌丰度,对土壤微生物生物量碳、氮含量没有产生显著影响,细菌丰度随着增温处理的温度上升呈现先上升再下降的趋势;增温处理下,微生物生物量与土壤全磷、硝态氮和可溶性有机氮含量呈正相关关系。未来需要加强针对气候变化对该类脆弱生态系统影响的监测,为农牧交错带温性草地管理提供预警及科学依据。

丛枝菌根真菌和解磷细菌双接种对小麦磷肥利用率的影响

试验采用单因素随机区组设计,以接种复合灭活菌剂为对照,分析了2种丛枝菌根真菌(Rhizoph-agus irregularis,RI;Glomus intraradices,GI)和4种解磷细菌(Bacillus amyloliquefaciens,BA;Bacillus megate-rium,BM;Arthrobacter pascens,AP;Bacillus subtilis,BS)双接种对小麦生长和磷肥利用率的影响。结果表明:(1)与对照相比,接菌组小麦的菌根侵染率、产量、速效磷含量均显著提高,而土壤pH值显著下降,小麦产量和速效磷含量在接菌处理下分别提高了7.31%~27.00%和19.03%~60.35%。(2)GI+AP处理的产量最高,添加RI接菌组的速效磷含量、碱性磷酸酶活性均高于添加GI的接菌组,其中以RI+BS处理的最高;RI+BS和RI+BA处理的磷肥吸收利用率最高,分别为30.86%和27.94%。(3)相关性分析结果表明,小麦磷肥吸收利用率与菌根侵染率、籽粒重、籽粒磷含量、速效磷含量、碱性磷酸酶活性呈极显著正相关,与叶片磷含量呈显著正相关,与土壤pH值呈极显著负相关。综上,双接种丛枝菌根真菌和解磷细菌有利于增强土壤碱性磷酸酶活性、增加土壤速效磷含量、降低土壤pH值,从而提高小麦产量和磷素积累量,其中RI+BS处理对小麦磷肥利用率的提高作用最为显著。

云产雪茄烟叶微生物群落、游离氨基酸及挥发性风味物质特征分析

为探究云南产区(以下简称“云产”)雪茄烟叶的品质差异,采用高通量测序和代谢组学技术等对云产雪茄烟叶的微生物群落结构、游离氨基酸和挥发性风味物质进行测定,通过O2PLS分析和相关性分析系统性地揭示产地微生物与烟叶风味品质之间的关系,并确定烟叶中的功能微生物和协同作用类群。结果表明:云产雪茄烟叶微生物群落结构存在产地差异,其中优势细菌主要为Aerococcus、Staphylococcus和Corynebacterium,优势真菌主要为Aspergillus、Cladosporium和Alternaria;雪茄烟叶中共检测出17种游离氨基酸,氨基酸含量整体表现为Asp含量最高,Met含量最低,味觉活性值较高的Asp和Glu对其呈味具有较大贡献,临沧云雪2号和普洱云雪2号雪茄烟叶游离氨基酸呈味特征较为突出;雪茄烟叶中共检测出65种挥发性风味物质,主要以酮类物质为主,甲基庚烯酮、β-大马酮、β-紫罗兰酮、癸醛、二氢猕猴桃内酯等16种差异风味物质对云产雪茄烟叶的风味形成具有重要作用,普洱2号的整体风味特征更加突出;Sphingomonas、Staphylococcus、Pseudomonas和Oceanobacillus之间的协同作用对烟叶的风味形成具有重要贡献,而Penicillium相对丰度与烟叶品质呈负相关。

细菌群落主导沙漠公路防护林营造后的土壤功能变化

防护林作为沙漠公路的安全保护屏障,其生长和应对胁迫所需的养分供给依赖于土壤微生物。以塔里木沙漠公路防护林和自然沙漠为研究系统,探究土壤细菌和真菌群落、两种生境共有和特有微生物物种变化对土壤物质循环功能的驱动作用。结果显示,土壤细菌和真菌物种丰富度(P<0.01,P<0.01)及群落组成(P<0.05,P<0.01)均受防护林营造的显著影响,细菌物种丰富度的响应增幅为77.5%,高于真菌22.1%。细菌群落是导致土壤酶活性升高的显著驱动因素,而非真菌群落或环境因子;细菌物种丰富度(rho=0.46,P<0.01)和群落组成(rho=0.68,P<0.01)与土壤酶之间呈显著偏Mantel相关。共有细菌相对丰度(rho=0.47,P<0.01)和特有细菌物种丰富度(rho=0.36,P<0.01)是驱动土壤酶活性改善的关键因素,与土壤酶之间呈显著偏Mantel相关。研究表明,沙漠公路防护林土壤细菌而非真菌主导微生物群落的响应,细菌群落通过改变本地物种丰度和新物种数量来调控土壤功能。

不同碳源下共存细菌对铜绿微囊藻生长的影响

铜绿微囊藻(Microcystis aeruginosa)可通过二氧化碳浓缩机制(carbon concentrating mechanism,CCM)利用水环境中的无机碳进行光合固碳来促进自身生长,是引发淡水蓝藻水华的优势种。自然水体生态系统中菌藻共生体系是其重要组成部分,对藻华起到重要调控作用,但有关不同碳源条件下共生细菌对蓝藻藻华的影响仍不清楚。文章以铜绿微囊藻为模式蓝藻,探究在不同碳源组合下共存细菌对其生长的影响。在总碳(total carbon,TC)质量浓度为25 mg/L的无机碳源和有机碳源组合,环境初始菌藻比为1∶2时,铜绿微囊藻的最大生物量达到最大值5.0×10^(7)个/mL,是纯藻对照组最大生物量的2.05倍;在加入25 mg/L的有机碳源,初始菌藻比为5∶1时,培养周期内可预测的最大生物量达到最小,为1.5×10^(7)个/mL,仅为纯藻对照组最大生物量的0.76倍。结果表明:不同碳源下初始细菌的出现会极大程度地影响铜绿微囊藻的生长,其中,在无机碳源和混合碳源的营养条件下,初始细菌显著加快了铜绿微囊藻的生长繁殖。