Plant diversity enhances soil fungal network stability indirectly through the increase of soil carbon and fungal keystone taxa richness.

Plant diversity is critical to the stability of ecosystems. However, our knowledge about the plant diversity effect on the stability of belowground communities is limited. Here, we characterized soil fungal diversity and co-occurrence network across a plant diversity gradient in a diversity manipulation experiment. We found that higher plant diversity resulted in higher fungal diversity, network complexity and stability. The positive plant diversity effect on fungal network stability was indirect via the increase of soil carbon and fungal keystone taxa richness based on structural equation modeling analysis. The model explained 44% variations of network stability when combining soil carbon and fungal keystone taxa richness, but explained approximate 30% variations of network stability when considering either one of the two factors, indicating that environmental filtering and biotic interaction processes play comparable roles in mediating the plant diversity effect on soil fungal network stability. The plant diversity-induced fungal network stability was significantly correlated with community-level functions including community resistance and enzyme activities. This study, from the view of networks, provides new insights into the plant diversity effect on the stability of soil microbial communities, which have implications for biodiversity conservation and policy development.

Arbuscular mycorrhizal fungi and plant diversity drive restoration of nitrogen-cycling microbial communities.

Soil microbial communities, key players of many crucial ecosystem functions, are susceptible to environmental disturbances, which might cause the loss of microbial diversity and functions. However, few ecological concepts and practices have been developed for rescuing stressed soil microbial communities. Here, we manipulated an experiment with or without arbuscular mycorrhizal fungi (AMF) inoculation and at three levels (one, three and six species) of plant diversity to disentangle how the AMF and vegetation rescue soil nitrogen (N) -cycling microbial loop from simulated degraded soil ecosystem. Our results showed that AMF inoculation improved the restoration of soil N-cycling microbial communities. This improved restoration was related to the role of AMF in enhancing interactions within the N-cycling microbial loop. Furthermore, increased plant diversity strengthened the role of AMF in rescuing N-cycling microbial communities. Our findings provide novel insights into the roles of AMF and plant diversity in facilitating the rescue of microbial communities in degraded terrestrial ecosystems.

Thiacloprid exposure perturbs the gut microbiota and reduces the survival status in honeybees.

Honeybees (Apis mellifera) offer ecosystem services such as pollination, conservation of biodiversity, and provision of food. However, in recent years, the number of honeybee colonies is diminishing rapidly, which is probably linked to the wide use of neonicotinoid insecticides. Middle-aged honeybees were fed with 50% (w/v) sucrose solution containing 0, 0.2, 0.6, and 2.0 mg/L thiacloprid (a neonicotinoid insecticide) for up to 13 days, and on each day of exposure experiment, percentage survival, sucrose consumption, and bodyweight of honeybees were measured. Further, changes in honeybee gut microbial community were examined using next-generation 16S rDNA amplicon sequencing on day 1, 7, and 13 of the exposure. When compared to control-treatment, continuous exposure to high (0.6 mg/L) and very high (2.0 mg/L) concentrations of thiacloprid significantly reduced percentage survival of honeybees (p < 0.001) and led to dysbiosis of their gut microbial community on day 7 of the exposure. However, during subsequent developmental stages of middle-aged honeybees (i.e. on day 13), their gut microbiome recovered from dysbiosis that occurred previously due to thiacloprid exposure. Taken together, improper application of thiacloprid can cause loss of honeybee colonies, while the microbial gut community of honeybee is an independent variable in this process.

Vibrio profundi sp. nov., isolated from a deep-sea seamount.

A Gram-stain negative, rod-shaped, facultative anaerobic, motile bacterial strain, designated TP187T, was isolated from a seamount near the Yap Trench in the tropical western Pacific. Phylogenetic analysis based on the 16S rRNA gene sequence showed that strain TP187T is related to members of the genus Vibrio and has high 16S rRNA gene sequence similarity with the type strains of Vibrio chagasii (97.3%) and Vibrio gallaecicus (97.1%). Sequence similarities to all other type strains of current species of the genus Vibrio were below 97%. The polar lipids profile was found to contain diphosphatidylglycerol, phosphatidylglycerol, an aminophospholipid, two aminolipids, four phospholipids and eleven unidentified polar lipids. Ubiquinone Q-8 was detected as the predominant quinone. The genomic DNA G + C content of strain TP187T was determined to be 43.7 mol%. In addition, the maximum values of in silico DNA-DNA hybridization (isDDH) and average nucleotide identity (ANI) between strain TP187T with V. chagasii LMG 21353T were 22.40 and 77.50% respectively. Both values are below the proposed cutoff levels for species delineation, i.e. 70 and 95%, respectively. Combined data from phenotypic, phylogenetic, isDDH and ANI data demonstrated that the strain TP187T is representative of a novel species of the genus Vibrio, for which we propose the name Vibrio profundi sp. nov. (type strain TP187T = KACC 18555T = CGMCC 1.15395T).

Pannonibacter carbonis sp. nov., isolated from coal mine water.

Two bacterial strains were isolated from coal mine water in China. Isolates were facultatively anaerobic, Gram-stain-negative, rod-shaped, motile by means of a single polar flagellum, and they did not produce bacteriochlorophyll α. Cells grew in tryptic soy broth with 0-5.5 % (w/v) NaCl, at 4-55 °C and pH 3.5-10.5. Isolates were positive for catalase, oxidase, urease, Voges-Proskauer test, gelatin hydrolysis and H2S production. Analysis of 16S rRNA gene sequences indicated that the closest relatives of strains Q4.6T and Q2.11 were the type strains Labrenzia suaedae DSM 22153T (97.4 %), Pannonibacter phragmitetus DSM 14782T (96.9 and 97.0 %) and Pannonibacter indicus DSM 23407T (96.8 %). The genomic average nucleotide identity (ANI) value for Q4.6T and Q2.11 was 100 %; however, this value was less than 77.7 % for the type strains P. phragmitetus and P. indicus, and less than 74.0 % for the type strain L. suaedae. The cellular fatty acid profile of strains Q4.6T and Q2.11 consisted primarily of C18 : 1ω7c. The principal quinone of the isolates was Q-10. The polar lipid profile consisted of diphosphatidyl glycerol, phosphatidyl glycerol, phosphatidyl ethanolamine and phosphatidyl choline. On the basis of phylogenetic analysis, genomic ANI analysis, DNA-DNA hybridization results, as well as phenotypic and chemotaxonomic data, strains Q4.6T and Q2.11 are assigned as a novel species within the genus Pannonibacter. The type strain is Pannonibacter carbonis Q4.6T (=CGMCC 1.15703T=KCTC 52466T).

Catechol 2,3-dioxygenase from a new phenolic compound degrader Thauera sp. K11: purification and biochemical characterization.

Catechol 2,3-dioxygenase (C23O) from a new phenolic compound degrader Thauera sp. K11 was purified and characterized. The native form of the enzyme was determined as a homotetramer with a molecular weight of 140 kDa, and its isoelectric point was close to 6.4. One iron per enzyme subunit was detected using atom absorption spectroscopy, and the effective size of C23O in its dilute solution (0.2 g L-1 , pH 8.0) was 14.5 nm. The optimal pH and temperature were 8.4 and 45 °C, respectively. The addition of Mg2+ , Cu2+ , Fe2+ , and Mn2+ could improve the enzyme activity, while Ag+ was found to be a strong inhibitor. C23O was stable in alkali conditions (pH 7.6-11.0) and thermostable below 50 °C. The final purified C23O had a sheet content of 53%, consistent with the theoretical value. This showed that the purified catechol 2,3-dioxygenase folded with a reasonable secondary structure.

Deinococcus petrolearius sp. nov. isolated from crude oil recovery water in China.

A Gram-stain positive, non-motile, spherical, red-pigmented and facultatively anaerobic bacterium, designated strain 6.1T, was isolated from a crude oil recovery water sample from the Huabei oil field in China. The novel strain exhibited tolerance of UV irradiation (> 1000 J m-2). Based on 16S rRNA gene sequence comparisons, strain 6.1T shows high similarity to Deinococcus citri DSM 24791T (98.1%) and Deinococcus gobiensis I-0T (97.8%), with less than 93.5% similarity to other closely related taxa. The major cellular fatty acids were identified as summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH), followed by iso-C17:1 ω9c and C16:0. The polar lipid profile was found to contain phospholipids, glycolipids, phosphoglycolipids and aminophospholipids. The predominant respiratory quinone was identified as MK-8. The DNA G + C content was determined to be 68.3 mol %. DNA-DNA hybridization between strain 6.1T and D. citri DSM 24791T was 45.6 ± 7.1% and with D. gobiensis I-OT was 36.6 ± 4.7%. On the basis of phylogenetic, chemotaxonomic and phenotypic data, we conclude strain 6.1T represents a novel species of the genus Deinococcus, for which we propose the name Deinococcus petrolearius sp. nov. The type strain is 6.1T (= CGMCC 1.15053T = KCTC 33744T).

Thauera sinica sp. nov., a phenol derivative-degrading bacterium isolated from activated sludge.

A bacterial strain, K11T, capable of degrading phenol derivatives was isolated from activated sludge of a sewage treatment plant in China. This strain, which can degrade more than ten phenol derivatives, was identified as a Gram-stain negative, rod-shaped, asporogenous, facultative anaerobic bacterium with a polar flagellum. The strain was found to grow in tryptic soy broth in the presence of 0-2.5% (w/v) NaCl (optimum 0-1%), at 4-43 °C (optimum 30-35 °C) and pH 4.5-10.5 (optimum 7.5-8). Comparative analysis of nearly full-length 16S rRNA gene sequences showed that this strain belongs to the genus Thauera. The 16S rRNA gene sequence was found to show high similarity (97.5%) to that of Thauera chlorobenzoica 3CB-1T, with lesser similarity to other recognised Thauera strains. The G+C content of the DNA of the strain was determined to be 67.8 mol%. The DNA-DNA hybridization value between K11T and Thauera aromatica DSM6984T was 10.4 ± 4.5%. The genomic OrthoANI values of K11T with the other nine type strains of genus Thauera were less than 81.1%. Chemotaxonomic analysis of strain K11T revealed that Q-8 is the predominant quinone; the polar lipids contain phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, two unidentified phospholipids and five uncharacterised lipids; the major cellular fatty acid was identified as summed feature 3 (C16:1 ω7c and/or iso-C15:0 2-OH; 45.9%), followed by C16:0 (20.5%) and C18:1 ω7c (15.8%). Based on the phenotypic and phylogenetic evidence, DNA-DNA hybridisation, OrthoANI, chemotaxonomic analysis and results of the physiological and biochemical tests, a new species named Thauera sinica sp. nov. is proposed with strain K11T (= CGMCC 1.15731T = KACC 19216T) designated as the type strain.

Sinorhodobacter hungdaonensis sp. nov. isolated from activated sludge collected from a municipal wastewater treatment plant.

A novel bacterium, strain L3T, was isolated from an activated sludge sample retrieved from a municipal wastewater treatment plant in Huangdao, China. On the basis of 16S rRNA gene sequence similarity studies, strain L3T was affiliated to the genus Sinorhodobacter, being most closely related to Sinorhodobacter ferrireducens (98.0 %). The 16S rRNA gene sequence similarity of strain L3T to other related species, Thioclava atlantica DLFJ1-1T (96.5 %), Rhodobacter capsulatus ATCC 11166T (96.3 %), Paenirhodobacter enshiensis DW2-9T (96.3 %) and Rhodobacter viridis JA737T (96.0 %) is less than 96.5 %. Chemotaxonomic characterization further supported classification of the strain to the genus Sinorhodobacter. The major polar lipid profile consists of diphosphatidyglycerol, phosphatidylglycerol and phosphatidylethanolamine. The major fatty acids are C18:1 ω7c (66.3 %), C16:0 (12.9 %) and C18:0 (8.0 %). The major quinone is Q-10. The G+C content of the genomic DNA of strain L3T is 68.0 mol %. DNA-DNA relatedness value between L3T and the closely related type strain S. ferrireducens SgZ-3T was 35.2 %. Based on these results, a new species Sinorhodobacter huangdaonensis is proposed. The type strain is L3T (= CGMCC 1.12963T = KCTC 42823T).

Complete genome sequence of the novel thermophilic polyhydroxyalkanoates producer Aneurinibacillus sp. XH2 isolated from Gudao oilfield in China.

Aneurinibacillus sp. XH2 (CGMCC 1.15535) was isolated from Gudao oilfield in China. It is able to use simple carbon resources to accumulate Polyhydroxyalkanoates (PHAs) in a thermophilic fashion. Here, we describe the genomic features of this strain. The total genome size of Aneurinibacillus sp. XH2 is 3,664,835bp and contains 3441 coding sequences and 114 tRNAs. The annotated genome sequence of this strain provides the genetic basis for revealing its role as a themophilic PHAs producing bacterium.