Towards establishing a fungal economics spectrum in soil saprobic fungi.

Trait-based frameworks are promising tools to understand the functional consequences of community shifts in response to environmental change. The applicability of these tools to soil microbes is limited by a lack of functional trait data and a focus on categorical traits. To address this gap for an important group of soil microorganisms, we identify trade-offs underlying a fungal economics spectrum based on a large trait collection in 28 saprobic fungal isolates, derived from a common grassland soil and grown in culture plates. In this dataset, ecologically relevant trait variation is best captured by a three-dimensional fungal economics space. The primary explanatory axis represents a dense-fast continuum, resembling dominant life-history trade-offs in other taxa. A second significant axis reflects mycelial flexibility, and a third one carbon acquisition traits. All three axes correlate with traits involved in soil carbon cycling. Since stress tolerance and fundamental niche gradients are primarily related to the dense-fast continuum, traits of the 2nd (carbon-use efficiency) and especially the 3rd (decomposition) orthogonal axes are independent of tested environmental stressors. These findings suggest a fungal economics space which can now be tested at broader scales.

Mameliella sediminis sp. nov., a novel polyhydroxyalkanoate-accumulating bacterium.

A Gram-stain-negative, strictly aerobic, non-motile, rod-shaped bacterium, capable of producing poly-ß-hydroxyalkanoate, designated DP3N28-2T, was isolated from the sediment collected from Daya Bay, Guangdong, PR China. Optimal growth occurred at 37-40 °C, pH 6.0 and in the presence of 4 % NaCl. The 16S rRNA gene sequences analysis revealed that DP3N28-2T showed highest similarities with Mameliella alba DSM 23384T (98.3 %), Antarctobacter jejuensis 13-2-B6T (97.2 %), Antarctobacter heliothermus El-219T (96.8 %), Maliponia aquimaris MM-10T (96.7 %), Ponticoccus litoralis CL-GR66T (96.4 %) and Aquicoccus porphyridii L1 8-17T (96.1 %). The predominant fatty acids (>10 %) were summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c; 72.1 %) and C16 : 0 (11.0 %). The polar lipids contain phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, one aminophosphlipid, one phospholipid and three unidentified lipids. The respiratory quinone was Q-10. The DNA G+C content was 63.0 mol% (data from the genome sequence). The estimated genome size was 5.12 Mb. The average nucleotide identity values between the DP3N28-2T genome and the genome of M. alba was 81.1 %, while the digital DNA-DNA hybridization value was 23.4 %. The phenotypic, genotypic and chemotaxonomic differences between DP3N28-2T and its phylogenetic relatives indicates that DP3N28-2T should be regarded as representing a novel species of the genus Mameliella, for which the name Mameliella sediminis sp. nov. is proposed. The type strain is DP3N28-2T (=MCCC 1K06218T=KCTC 82804T).

Maritimibacter dapengensis sp. nov., a poly-ß-hydroxyalkanoates-producing bacterium isolated from sediment of the Dapeng peninsula (Guangdong, China).

A Gram-negative, obligate aerobic, non-motile, rod-shaped bacterium lacking a flagellum, was isolated from sediment sampled at the Dapeng peninsula of Shenzhen, Guangdong, China, and designated strain DP4N28-5T. Growth of strain DP4N28-5T occurred at 15-45 °C (optimum at 30 °C), pH 6.0-8.0 (optimum at 6.0) and in 2.0-10.0 % NaCl (w/v; optimum at 2.0-3.0 %). The 16S rRNA gene sequence analysis revealed that strain DP4N28-5T was most closely related to Maritimibacter alkaliphilus DSM 100037T (97.6 %; sequence similarity). The strain synthesized a trace amount of poly-ß-hydroxybutyrate. The dominant cellular fatty acids were summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c), C16 : 0, 11-mehtyl C18 : 1 ω7c and C16 : 0 2-OH. The major polar lipids included phosphatidylethanolamine, phosphatidylglycerol, phosphatidylmethylethanolamine, one unidentified aminophospholipid, three unidentified aminolipids and four unidentified lipids. The respiratory quinone was Q-10. The DNA G+C content was 62.0 mol% and the estimated genome size was 3.9 Mbp. The calculated average nucleotide value between strain DP4N28-5T and M. alkaliphilus DSM 100037T was 78.1 %. The phenotypic, genotypic and chemotaxonomic differences between strain DP4N28-5T and its phylogenetic relatives indicate that DP4N28-5T represents a novel species in the genus Maritimibacter, for which the name Maritimibacter dapengensis sp. nov. is proposed. The type strain is DP4N28-5T (=MCCC 1K05640T=KCTC 82805T). The description of genus Maritimibacter was emended to include this new species.

Multifunctional, Robust, and Porous PHBV-GO/MXene Composite Membranes with Good Hydrophilicity, Antibacterial Activity, and Platelet Adsorption Performance.

The limitations of hydrophilicity, strength, antibacterial activity adsorption performance of the biobased and biocompatible polymer materials, such as polyhydroxyalkanoates (PHAs), significantly restrict their wider applications especially in medical areas. In this paper, a novel composite membrane with high antibacterial activity and platelet adsorption performance was prepared based on graphene oxide (GO), MXene and 3-hydroxybutyrate-co-hydroxyvalerate (PHBV), which are medium-chain-length-copolymers of PHA. The GO/MXene nanosheets can uniformly inset on the surface of PHBV fibre and give the PHBV-GO/MXene composite membranes superior hydrophilicity due to the presence of hydroxyl groups and terminal oxygen on the surface of nanosheets, which further provides the functional site for the free radical polymerization of ester bonds between GO/MXene and PHBV. As a result, the tensile strength, platelet adsorption, and blood coagulation time of the PHBV-GO/MXene composite membranes were remarkably increased compared with those of the pure PHBV membranes. The antibacterial rate of the PHBV-GO/MXene composite membranes against gram-positive and gram-negative bacteria can reach 97% due to the antibacterial nature of MXene. The improved strength, hydrophilicity, antibacterial activity and platelet adsorption performance suggest that PHBV-GO/MXene composite membranes might be ideal candidates for multifunctional materials for haemostatic applications.

Growth rate trades off with enzymatic investment in soil filamentous fungi.

Saprobic soil fungi drive many important ecosystem processes, including decomposition, and many of their effects are related to growth rate and enzymatic ability. In mycology, there has long been the implicit assumption of a trade-off between growth and enzymatic investment, which we test here using a set of filamentous fungi from the same soil. For these fungi we measured growth rate (as colony radial extension) and enzymatic repertoire (activities of four enzymes: laccase, cellobiohydrolase, leucine aminopeptidase and acid phosphatase), and explored the interaction between the traits based on phylogenetically corrected methods. Our results support the existence of a trade-off, however only for the enzymes presumably representing a larger metabolic cost (laccase and cellobiohydrolase). Our study offers new insights into potential functional complementarity within the soil fungal community in ecosystem processes, and experimentally supports an enzymatic investment/growth rate trade-off underpinning phenomena including substrate succession.

Tradeoffs in hyphal traits determine mycelium architecture in saprobic fungi.

The fungal mycelium represents the essence of the fungal lifestyle, and understanding how a mycelium is constructed is of fundamental importance in fungal biology and ecology. Previous studies have examined initial developmental patterns or focused on a few strains, often mutants of model species, and frequently grown under non-harmonized growth conditions; these factors currently collectively hamper systematic insights into rules of mycelium architecture. To address this, we here use a broader suite of fungi (31 species including members of the Ascomycota, Basidiomycota and Mucoromycota), all isolated from the same soil, and tested for ten architectural traits under standardized laboratory conditions. We find great variability in traits among the saprobic fungal species, and detect several clear tradeoffs in mycelial architecture, for example between internodal length and hyphal diameter. Within the constraints so identified, we document otherwise great versatility in mycelium architecture in this set of fungi, and there was no evidence of trait 'syndromes' as might be expected. Our results point to an important dimension of fungal properties with likely consequences for coexistence within local communities, as well as for functional complementarity (e.g. decomposition, soil aggregation).

Thauera lacus sp. nov., isolated from a saline lake in Inner Mongolia.

A Gram-stain-negative, facultatively anaerobic, motile and rod-shaped bacterium, designated D20T, was isolated from the saline Lake Dai in Inner Mongolia, PR China. Growth of strain D20T occurred at 25-45 °C (optimum, 40 °C), pH 4.0-12.0 (optimum, 8.0) and with 0-3 % NaCl (w/v); (optimum, 0-1 %). The results of 16S rRNA gene sequence analysis revealed that strain D20T was most closely related to three Thauera species, Thaueraselenatis AXT, Thaueraaminoaromatica S2T and Thaueraaromatica K172T, with a similarity value of 96.2 %. The major respiratory quinone of strain D20T was ubiquinone-8 (Q-8), and the dominant fatty acids (>10 %) were summed feature 3 (C16 : 1ω6c and/or C16 : 1ω7c; 39.8 %), C16 : 0 (30.9 %) and summed feature 8 (C18 : 1ω6c and/or C18 : 1ω7c; 13.5 %). The polar lipid profile contained phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, one aminophospholipid and five unidentified lipids. The DNA G+C content was 67.2 mol% (data from the genome sequence). The estimated genome size was 3.7 Mb. The phenotypic, genotypic and chemotaxonomic differences between strain D20T and its phylogenetic relatives indicated that strain D20T should be regarded as a novel species in the genus Thauera, for which the name Thaueralacus sp. nov. is proposed. The type strain is D20T (=MCCC 1H00305T=KCTC 62586T).

Aquiflexum aquatile sp. nov., isolated from lake water.

A Gram-stain-negative, facultative anaerobic, red-coloured, rod-shaped, non-flagellated, non-motile and non-gliding bacterium, designated strain Z0201T, was isolated from lake water in Yunnan, China (26° 16' N, 99° 94' E). Cells of strain Z0201T were 0.2-0.4 µm wide and 1.4-2.5 µm long, catalase-positive and oxidase-negative. Strain Z0201T was found to grow at 4-37 °C (optimum, 30 °C) and pH 6.5-8.5 (pH 7.5) in the presence of 0-2.0 % (w/v) NaCl (0-0.5 %). The sole respiratory quinone of strain Z0201T was MK-7 and the DNA G+C content was 41.2 mol%. The major fatty acid was iso-C15 : 0 (49.4 %). The polar lipid profile of strain Z0201T consisted of aminophospholipid, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylethanolamine, two unidentified phospholipids and five unidentified lipids. Based on the 16S rRNA gene sequence analysis, strain Z0201T was a member of the genus Aquiflexum, appearing to be closely related to Aquiflexum balticum (95.4 %). On the basis of phenotypic distinctiveness and phylogenetic divergence, strain Z0201T is considered to represent a novel species of the genus Aquiflexum, for which the name Aquiflexumaquatile sp. nov. is proposed. The type strain is Z0201T (=KCTC 62450T=MCCC 1H00328T).

Fungal Traits Important for Soil Aggregation.

Soil structure, the complex arrangement of soil into aggregates and pore spaces, is a key feature of soils and soil biota. Among them, filamentous saprobic fungi have well-documented effects on soil aggregation. However, it is unclear what properties, or traits, determine the overall positive effect of fungi on soil aggregation. To achieve progress, it would be helpful to systematically investigate a broad suite of fungal species for their trait expression and the relation of these traits to soil aggregation. Here, we apply a trait-based approach to a set of 15 traits measured under standardized conditions on 31 fungal strains including Ascomycota, Basidiomycota, and Mucoromycota, all isolated from the same soil. We find large differences among these fungi in their ability to aggregate soil, including neutral to positive effects, and we document large differences in trait expression among strains. We identify biomass density, i.e., the density with which a mycelium grows (positive effects), leucine aminopeptidase activity (negative effects) and phylogeny as important factors explaining differences in soil aggregate formation (SAF) among fungal strains; importantly, growth rate was not among the important traits. Our results point to a typical suite of traits characterizing fungi that are good soil aggregators, and our findings illustrate the power of employing a trait-based approach to unravel biological mechanisms underpinning soil aggregation. Such an approach could now be extended also to other soil biota groups. In an applied context of restoration and agriculture, such trait information can inform management, for example to prioritize practices that favor the expression of more desirable fungal traits.

Aliidiomarina celeris sp. nov., isolated from coastal sediment.

A Gram-stain-negative, heterotrophic, facultative anaerobic, gliding and motile bacterium, approximately 0.6-0.9 µm wide and 1.5-2.6 µm long, designated F3105T, was isolated from a marine sediment sample collected along the coast of Rongcheng, China . The growth of strain F3105T occurred on media with 1.0-8.0 % (w/v) NaCl (optimum, 2.0-3.0 %) and a pH of 6.5-9.5 (optimum, pH 7.5) at 4-45 °C (optimum, 37 °C). The phylogenetic analysis of the 16S rRNA gene and chemotaxonomic data revealed that the isolate belonged to the genus Aliidiomarina, and is closely related to Aliidiomarina shirensis (95.9 % sequence similarity). The sole isoprenoid quinone was Q-8. The major cellular fatty acids of the isolate were iso-C15 : 0, iso-C17 : 1ω9c and iso-C17 : 0, and its polar lipids consisted of phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, aminolipid, two unidentified lipids and two unidentified aminophospholipids. The DNA G+C content of strain F3105T was 49.5 mol%. On the basis of phenotypic distinctiveness and phylogenetic divergence, strain F3105T is considered to represent a novel species of the genus Aliidiomarina, for which the name Aliidiomarinaceleris sp. nov. is proposed. The type strain is F3105T (=MCCC 1H00223T=KCTC 52891T).

Arbuscular mycorrhizal fungi increase grain yields: a meta-analysis.

Increasing grain yields of food cereal crops is a major goal in future sustainable agriculture. We quantitatively analyzed the potential role of arbuscular mycorrhizal (AM) fungi in enhancing grain yields of seven cereal crops with exceptional importance for human nutrition across the globe: corn, wheat, rice, barley, sorghum, millet and oat. We conducted a meta-analysis for three datasets including both English and Chinese language publications: the 'whole' dataset including both laboratory and field studies (168 articles); the 'field' dataset comprising only field studies (97 studies); and the 'field-inoculation' dataset including only AM fungal inoculation studies conducted in field conditions (70 articles). We found that the AM fungal effect on grain yield was less pronounced in field and noninoculation studies. AM fungal inoculation in field led to a 16% increase (overall effect) based on the 'field-inoculation' dataset; this effect was variable (77% trials had positive values), crop-specific, lower for new cultivars released after 1950 and further modulated by soil pH. Although there are neutral and negative effects of AM fungi on grain yields, we emphasize the importance of integrating AM fungi in sustainable agriculture to increase grain yields of cereal crops.

Soil biota contributions to soil aggregation.

Humankind depends on the sustainability of soils for its survival and well-being. Threatened by a rapidly changing world, our soils suffer from degradation and biodiversity loss, making it increasingly important to understand the role of soil biodiversity in soil aggregation-a key parameter for soil sustainability. Here, we provide evidence of the contribution of soil biota to soil aggregation on macro- and microaggregate scales, and evaluate how specific traits, soil biota groups and species interactions contribute to this. We conducted a global meta-analysis comprising 279 soil biota species. Our study shows a clear positive effect of soil biota on soil aggregation, with bacteria and fungi generally appearing to be more important for soil aggregation than soil animals. Bacteria contribute strongly to both macro- and microaggregates while fungi strongly affect macroaggregation. Motility, body size and population density were important traits modulating effect sizes. Investigating species interactions across major taxonomic groups revealed their beneficial impact on soil aggregation. At the broadest level, our results highlight the need to consider biodiversity as a causal factor in soil aggregation. This will require a shift from the current management and physicochemical perspective to an approach that fully embraces the significance of soil organisms, their diversity and interactions.

Salinimicrobium flavum sp. nov., isolated from coastal sediment.

A novel Gram-stain-negative, non-gliding, facultatively anaerobic and rod-shaped bacterium, designated X7T, was isolated from marine sediment taken from the coast of Weihai, China. Strain X7T grew optimally at 28-30 °C, at pH 7.0 and in the presence of 2-3 % (w/v) NaCl. Based on the 16S rRNA gene sequence analysis, strain X7T was a member of the genus Salinimicrobium and was most closely related to the species Salinimicrobium gaetbulicola with a 96.3 % 16S rRNA gene sequence similarity value. The major cellular fatty acids of strain X7T were anteiso-C15 : 0, iso-C15 : 0, anteiso-C17 : 1ω9c, iso-C17 : 1ω9c, C17 : 0 2-OH and iso-C17 : 0 3-OH. The major polar lipids of strain X7T were phosphatidylethanolamine, one unidentified phospholipid, two unidentified aminolipids and five unidentified lipids. The predominant respiratory quinone was MK-6, and the genomic DNA G+C content was 46.7 mol%. Phylogenetic, phenotypic, chemotaxonomic and genotypic results indicated that strain X7T represents a novel species of the genus Salinimicrobium, for which the name Salinimicrobium flavum sp. nov. is proposed. The type strain is X7T (=KCTC 42585T=MCCC 1H00115T).

Confluentibacter citreus sp. nov., isolated from lake sediment, and emended description of the genus Confluentibacter.

A Gram-stain-negative, non-gliding, aerobic and rod-shaped bacterium, designated XJNYT, was isolated from Sayram Lake (44° 30' 30.41″ N 81° 12' 39.55″ E), Xinjiang Province, north-west China, and was characterized taxonomically by a polyphasic study. Strain XJNYT grew at salinities of 0-4 % (w/v) and temperatures of 4-37 °C. The pH range for growth was 6.5-8.5. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain XJNYT belonged to the genus Confluentibacter and was closely related to the type strain of Confluentibacter lentus with 97.8 % similarity. The DNA G+C content was 34.5 mol%. The major fatty acids were iso-C15 : 0, iso-C15 : 1 G, anteiso-C15 : 0, iso-C15 : 0 3-OH, C17 : 0 2-OH and iso-C17 : 0 3-OH. The major respiratory isoprenoid quinone was menaquinone-6 (MK-6) and the polar lipids were phosphatidylethanolamine, an unidentified phospholipid, two unidentified aminolipids and four unidentified lipids. On the basis of morphological, physiological and molecular properties and phylogenetic distinctiveness, strain XJNYT represents a novel species within the genus Confluentibacter, for which the name Confluentibactercitreus sp. nov. is proposed. The type strain is XJNYT (=KCTC 52638T=MCCC 1H00183T).

Soluble protein and acid phosphatase exuded by ectomycorrhizal fungi and seedlings in response to excessive Cu and Cd.

Fungi and their symbionts can alleviate heavy metal stress by exuding soluble proteins and enzymes. This study examined the role of soluble protein and acid phosphatase (APase) exuded by Xerocomus chrysenteron, an ectomycorrhizal fungus, and the seedlings of its symbiont, Chinese pine (Pinus tabulaeformis), under conditions of excessive Cu and Cd. The growth type showed that this poorly studied ectomycorrhizal fungus was capable of tolerating high concentrations of Cu, and may be useful in phytoremediation. X. chrysenteron grew well at 80 mg/L Cu, and the EC50 for Cd was 17.82 mg/L. X. chrysenteron also showed enhanced exudation of soluble protein in both isolated and inoculated cultivations under the influence of Cu and Cd. Soluble protein exudation, however, differed under Cu and Cd stress in isolates. In mediums containing Cu, soluble protein exudation increased with concentration, but in mediums containing Cd the content of soluble protein increased to a comparable level at all concentrations. This study demonstrated that soluble protein was related to heavy metal tolerance, although the different ions played different roles. While APase activity in exudates of fungi and seedlings decreased under Cu and Cd stress in comparison to the control, the APase activity in seedlings was maintained by inoculation. Thus, X. chrysenteron facilitated the ability of plant to maintain a normal nutrient uptake, and therefore to protect it from heavy metal toxicity.