Signature fatty acids in the polar lipids of acid-producingThiobacillusspp.: Methoxy, cyclopropyl, alpha-hydroxy-cyclopropyl and branched and normal monoenoic fatty acids

Bacterial precursors and unsaturated long-chain fatty acids are biomarkers of North-Atlantic deep-sea demosponges

Sponges produce distinct fatty acids (FAs) that (potentially) can be used as chemotaxonomic and ecological biomarkers to study endosymbiont-host interactions and the functional ecology of sponges. Here, we present FA profiles of five common habitat-building deep-sea sponges (class Demospongiae, order Tetractinellida), which are classified as high microbial abundance (HMA) species. Geodia hentscheli, G. parva, G. atlantica, G. barretti, and Stelletta rhaphidiophora were collected from boreal and Arctic sponge grounds in the North-Atlantic Ocean. Bacterial FAs dominated in all five species and particularly isomeric mixtures of mid-chain branched FAs (MBFAs, 8- and 9-Me-C_16:0 and 10- and 11-Me-C_18:0) were found in high abundance (together ≥ 20% of total FAs) aside more common bacterial markers. In addition, the sponges produced long-chain linear, mid- and a(i)-branched unsaturated FAs (LCFAs) with a chain length of 24‒28 C atoms and had predominantly the typical Δ^5,9 unsaturation, although the Δ^9,19 and (yet undescribed) Δ^11,21 unsaturations were also identified. G. parva and S. rhaphidiophora each produced distinct LCFAs, while G. atlantica, G. barretti, and G. hentscheli produced similar LCFAs, but in different ratios. The different bacterial precursors varied in carbon isotopic composition (δ¹³C), with MBFAs being more enriched compared to other bacterial (linear and a(i)-branched) FAs. We propose biosynthetic pathways for different LCFAs from their bacterial precursors, that are consistent with small isotopic differences found in LCFAs. Indeed, FA profiles of deep-sea sponges can serve as chemotaxonomic markers and support the concept that sponges acquire building blocks from their endosymbiotic bacteria.

Acyl-group specificity of AHL synthases involved in quorum-sensing in Roseobacter group bacteria

N-Acylhomoserine lactones (AHLs) are important bacterial messengers, mediating different bacterial traits by quorum sensing in a cell-density dependent manner. AHLs are also produced by many bacteria of the marine Roseobacter group, which constitutes a large group within the marine microbiome. Often, specific mixtures of AHLs differing in chain length and oxidation status are produced by bacteria, but how the biosynthetic enzymes, LuxI homologs, are selecting the correct acyl precursors is largely unknown. We have analyzed the AHL production in Dinoroseobacter shibae and three Phaeobacter inhibens strains, revealing strain-specific mixtures. Although large differences were present between the species, the fatty acid profiles, the pool for the acyl precursors for AHL biosynthesis, were very similar. To test the acyl-chain selectivity, the three enzymes LuxI₁ and LuxI₂ from D. shibae DFL-12 as well as PgaI₂ from P. inhibens DSM 17395 were heterologously expressed in E. coli and the enzymes isolated for in vitro incubation experiments. The enzymes readily accepted shortened acyl coenzyme A analogs, N-pantothenoylcysteamine thioesters of fatty acids (PCEs). Fifteen PCEs were synthesized, varying in chain length from C₄ to C₂₀, the degree of unsaturation and also including unusual acid esters, e.g., 2E,11Z-C18:2-PCE. The latter served as a precursor of the major AHL of D. shibae DFL-12 LuxI₁, 2E,11Z-C18:2-homoserine lactone (HSL). Incubation experiments revealed that PgaI₂ accepts all substrates except C₄ and C₂₀-PCE. Competition experiments demonstrated a preference of this enzyme for C₁₀ and C₁₂ PCEs. In contrast, the LuxI enzymes of D. shibae are more selective. While 2E,11Z-C18:2-PCE is preferentially accepted by LuxI₁, all other PCEs were not, except for the shorter, saturated C₁₀–C₁₄-PCEs. The AHL synthase LuxI₂ accepted only C₁₄ PCE and 3-hydroxydecanoyl-PCE. In summary, chain-length selectivity in AHLs can vary between different AHL enzymes. Both, a broad substrate acceptance and tuned specificity occur in the investigated enzymes.

Chemoautotrophic carbon fixation rates and active bacterial communities in intertidal marine sediments

Chemoautotrophy has been little studied in typical coastal marine sediments, but may be an important component of carbon recycling as intense anaerobic mineralization processes in these sediments lead to accumulation of high amounts of reduced compounds, such as sulfides and ammonium. We studied chemoautotrophy by measuring dark-fixation of ¹³C-bicarbonate into phospholipid derived fatty acid (PLFA) biomarkers at two coastal sediment sites with contrasting sulfur chemistry in the Eastern Scheldt estuary, the Netherlands. At one site where free sulfide accumulated in the pore water right to the top of the sediment, PLFA labeling was restricted to compounds typically found in sulfur and ammonium oxidizing bacteria. At the other site, with no detectable free sulfide in the pore water, a very different PLFA labeling pattern was found with high amounts of label in branched i- and a-PLFA besides the typical compounds for sulfur and ammonium oxidizing bacteria. This suggests that other types of chemoautotrophic bacteria were also active, most likely Deltaproteobacteria related to sulfate reducers. Maximum rates of chemoautotrophy were detected in first 1 to 2 centimeters of both sediments and chemosynthetic biomass production was high ranging from 3 to 36 mmol C m⁻² d⁻¹. Average dark carbon fixation to sediment oxygen uptake ratios were 0.22±0.07 mol C (mol O₂)⁻¹, which is in the range of the maximum growth yields reported for sulfur oxidizing bacteria indicating highly efficient growth. Chemoautotrophic biomass production was similar to carbon mineralization rates in the top of the free sulfide site, suggesting that chemoautotrophic bacteria could play a crucial role in the microbial food web and labeling in eukaryotic poly-unsaturated PLFA was indeed detectable. Our study shows that dark carbon fixation by chemoautotrophic bacteria is a major process in the carbon cycle of coastal sediments, and should therefore receive more attention in future studies on sediment biogeochemistry and microbial ecology.

Methoxylated fatty acids from the bark of Fraxinus sieboldiana

Nine new fatty acid derivatives, including seven methoxylated (1, 2, and 4-8) and two hydroxylated (3 and 9) fatty acids, have been isolated from the ethanol extract of the stem bark of Fraxinus sieboldiana. Their structures were determined by spectroscopic methods including IR, MS, 1D, and 2D NMR experiments. The 3- or 9-methoxylated fatty acids are reported for the first time in nature.

Organic matter in sediments of an acidic mining lake as assessed by lipid analysis. Part I: fatty acids

Fatty acid (FA) patterns of sediments collected from the bottom of an acidic mine pit lake (AML) at different depths (surface sediment: 0 to 1cm; deep sediment: 4 to 5 cm) were studied to characterize microbial communities and the sources of sedimentary organic matter (SOM). Studies were performed on the molecular level utilizing source-specific, diagnostic FA biomarkers. The biomarker-based approach has been used widely in marine sediment studies, but has not been applied for sediments from AMLs so far. Combined FA concentrations in the surface sediment were higher compared to those in the deep sediment (497 vs. 127 μg g(-1)d.w., respectively). This was related to deposition of autochthonous biomass and higher terrestrial plants onto the surface sediment, as well as--to lesser extent--with higher bacterial activity on the sediment-water interface. The FA distribution in both sediments was characterized by a strong even-over-odd preference and was bimodal in nature: there was a cluster at nC(14)-nC(18) characteristic of chiefly autochthonous (algal and bacterial) SOM production, and another cluster at nC(22-28) related to input from higher plants. The FA distribution in the surface sediment pointed to higher terrestrial input compared to autochthonous contribution to SOM (67%:33%) as an estimate. Fingerprinting of viable bacteria was accomplished through signature FA markers including branched C(15) and C(17) surrogates, cyclopropanoic acids, 3-hydroxy (OH) acids and monounsaturated surrogates with unusual double bond localization. The abundance of Gram-negative bacteria was higher in the surface sediment as evidenced by total diagnostic 3-OH-fatty acids (37 μg g(-1) versus 25 μg g(-1)). Potential source taxa in both sediment layers included acidophilic iron- and sulfur-oxidizing bacteria including Acidithiobacillus ferrooxidans. High abundances of terminally branched C(15) and C(17) surrogates in both sediments pointed to sulfate- and iron-reducing bacteria. Signature FAs characteristic of methanotrophs were virtually lacking in both sediments.

Double bond migration to methylidene positions during electron ionization mass spectrometry of branched monounsaturated fatty acid derivatives

Electron ionization mass spectra of several monounsaturated methyl-branched fatty acid methyl and trimethylsilyl esters were examined. These spectra exhibited some intensive fragment ions, whose formation could be explained after double-bond migration to methylidene position. This preferential migration (substantiated by deuterium labeling) acts significantly in the case of monounsaturated fatty acid methyl and trimethylsilyl esters possessing a methyl branch localized between the penultimate and the C(4) positions (relative to the ester group), whatever the position of the double-bond. Allylic cleavage and gamma-hydrogen rearrangement of the ionized methylidene group thus formed afforded very interesting fragment ions, which could be particularly useful to determine branching positions of monounsaturated methyl-branched fatty acid methyl and trimethylsilyl esters without additional treatment.

Soil microbial community associated with an invasive grass differentially impacts native plant performance

This study is one of the first to show that invasive plant-induced changes in the soil microbial community can negatively impact native plant performance. This greenhouse experiment tested whether soil microbial communities specific to the rhizospheres of an invasive grass (Aegilops triuncialis) and two native plants (Lasthenia californica and Plantago erecta) affected invasive and/or native plant performance. Each of these species were grown in separate pots for 2 months to prime the soils with plant-specific rhizosphere microbial communities. Each plant species was then planted in native- and invasive-primed soil, and effects on plant performance were monitored. At 5 months, differences in microbial biomarker fatty acids between invaded and native soils mirrored previous differences found in field-collected soil. L. californica performance was significantly reduced when grown in invaded soil compared to native soil (flowering date was delayed, aboveground biomass decreased, specific root length increased, and root mass ratio increased). In contrast, P. erecta and A. triuncialis performance were unaffected when grown in invaded vs native soil. These results suggest that in some cases, invasion-induced changes in the soil microbial community may contribute to a positive feedback loop, leading to the increased dominance of invasive species in an ecosystem.

Description of Labrenzia alexandrii gen. nov., sp. nov., a novel alphaproteobacterium containing bacteriochlorophyll a, and a proposal for reclassification of Stappia aggregata as Labrenzia aggregata comb. nov., of Stappia marina as Labrenzia marina comb. nov. and of Stappia alba as Labrenzia alba comb. nov., and emended descriptions of the genera Pannonibacter, Stappia and Roseibium, and of the species Roseibium denhamense and Roseibium hamelinense

A slightly pink-coloured strain, strain DFL-11T, was isolated from single cells of the marine dinoflagellate Alexandrium lusitanicum and was found to contain the genes encoding two proteins of the photosynthetic reaction centre, pufL and pufM. 16S rRNA gene sequence analysis revealed that the novel strain belonged to the α-2 subgroup of the Proteobacteria and was most closely related to Stappia aggregata (97.7 % similarity), Stappia alba (98.0 %) and Stappia marina (98.0 %). Dark-grown cells of strain DFL-11T contained small amounts of bacteriochlorophyll a (bchl a) and a carotenoid. Cells of strain DFL-11T were rods, 0.5–0.7×0.9–3.0 μm in size and motile by means of a single, subpolarly inserted flagellum. The novel strain was strictly aerobic and utilized a wide range of organic carbon sources, including fatty acids, tricarboxylic acid cycle intermediates and sugars. Biotin and thiamine were required as growth factors. Growth was obtained at sea salt concentrations of between 1 and 10 % (w/v), at a pH between 6 and 9.2 and at a temperature of up to 33 °C (optimum, 26 °C). Nitrate was not reduced and indole was not produced from tryptophan. Strain DFL11T was resistant to potassium tellurite and transformed it to elemental tellurium. The major respiratory lipoquinone was ubiquinone 10 (Q10). The polar lipids comprised phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylcholine, an unidentified aminolipid and the glycolipid sulphoquinovosyldiacylglyceride. The fatty acids comprised 16 : 1ω7c, 16 : 0, 18 : 1ω7c, 18 : 0, 11-methyl 18 : 1ω6t, 11-methyl 20 : 1ω6t, 20 : 1ω7c, 22 : 0, 22 : 1 and the hydroxy fatty acids 3-OH 14 : 0, 3-OH 16 : 0 (ester-linked), 3-OH 18 : 0, 3-OH 20 : 1 and 3-OH 20 : 0, all of which are amide-linked. The DNA G+C value was 56 mol%. Comparative analysis of α-2 subgroup 16S rRNA gene sequences showed that the type species of the genus Stappia, Stappia stellulata, is only distantly related to S. aggregata (95.3 % sequence similarity). Based on the combination of the 16S rRNA gene sequence data, a detailed chemotaxonomic study and the biochemical and physiological properties of members of the genera Stappia, Pannonibacter and Roseibium, it is proposed that S. aggregata, S. alba, S. marina are transferred to a new genus, Labrenzia gen. nov., as Labrenzia aggregata comb. nov., Labrenzia alba comb. nov. and Labrenzia marina comb. nov. The type species of the new genus is Labrenzia alexandrii sp. nov., with strain DFL-11T (=DSM 17067T=NCIMB 14079T) as the type strain. The pufLM genes of the photosynthesis reaction centre were shown to be present in some, but not all, species of the new genus Labrenzia and they were identified for the first time in S. stellulata. In accordance with the new data collected in this study, emended descriptions are provided for the genera Pannonibacter, Roseibium and Stappia.

Methoxylated fatty acids in Blumeria graminis conidia

The total fatty acids (FA) composition of Blumeria graminis f.sp. tritici conidia, the causal agent of wheat powdery mildew, was analyzed as a function of their age. A total of 19 FA (C12-C24 saturated and unsaturated) and unusual methoxylated fatty acids (mFA) were detected in young, intermediate and old conidia. Two very long chain methoxylated FA were identified by GC-MS as 3-methoxydocosanoic and 3-methoxytetracosanoic acids. Medium chain FA were predominant in young conidia (75%, including 13% of mFA) while very long chain fatty acids constituted the major compounds in old conidia (74%, including 30% of mFA). We have shown for the first time that the total FA composition is strongly correlated with the age of B. graminis f.sp. tritici (Bgt) conidia.

GC-MS structural characterization of fatty acids from marine aerobic anoxygenic phototrophic bacteria

The FA composition of 12 strains of marine aerobic anoxygenic phototrophic bacteria belonging to the genera Erythrobacter, Roseobacter, and Citromicrobium was investigated. GC-MS analyses of different types of derivatives were performed to determine the structures of the main FA present in these organisms. All the analyzed strains contained the relatively rare 11-methyloctadec-12-enoic acid, and three contained 12-methyl-octadec-11-enoic acid, which has apparently never been reported before. High amounts of the very unusual octadeca-5,11-dienoic acid were present in 9 of the 12 strains analyzed. A FA containing a furan ring was detected in three strains. Analytical data indicated that this FA was 10,13-epoxy-11-methyloctadeca-10,12-dienoic acid. A very interesting enzymatic peroxidation of the allylic carbon 10 of cis-vaccenic acid was observed in three strains. Deuterium labeling and GC-MS analyses enabled us to demonstrate that this enzymatic process involves the initial dioxygenase-mediated formation of 10-hydroperoxyoctadec-11(cis)-enoic acid, which is then isomerized to 10-hydroperoxyoctadec-11(trans)-enoic acid and converted to the corresponding hydroxyacids and oxoacids. Different biosynthetic pathways were proposed for these different compounds.

The use of phospholipid fatty acid analysis to measure impact of acid rock drainage on microbial communities in sediments

The impact of acid rock drainage (ARD) and eutrophication on microbial communities in stream sediments above and below an abandoned mine site in the Adelaide Hills, South Australia, was quantified by PLFA analysis. Multivariate analysis of water quality parameters, including anions, soluble heavy metals, pH, and conductivity, as well as total extractable metal concentrations in sediments, produced clustering of sample sites into three distinct groups. These groups corresponded with levels of nutrient enrichment and/or concentration of pollutants associated with ARD. Total PLFA concentration, which is indicative of microbial biomass, was reduced by >70% at sites along the stream between the mine site and as far as 18 km downstream. Further downstream, however, recovery of the microbial abundance was apparent, possibly reflecting dilution effect by downstream tributaries. Total PLFA was >40% higher at, and immediately below, the mine site (0-0.1 km), compared with sites further downstream (2.5-18 km), even after accounting for differences in specific surface area of different sediment samples. The increased microbial population in the proximity of the mine source may be associated with the presence of a thriving iron-oxidizing bacteria community as a consequence of optimal conditions for these organisms while the lower microbial population further downstream corresponded with greater sediments' metal concentrations. PCA of relative abundance revealed a number of PLFAs which were most influential in discriminating between ARD-polluted sites and the rest of the sites. These PLFA included the hydroxy fatty acids: 2OH12:0, 3OH12:0, 2OH16:0; the fungal marker: 18:2omega6; the sulfate-reducing bacteria marker 10Me16:1omega7; and the saturated fatty acids 12:0, 16:0, 18:0. Partial constrained ordination revealed that the environmental parameters with the greatest bearing on the PLFA profiles included pH, soluble aluminum, total extractable iron, and zinc. The study demonstrated the successful application of PLFA analysis to rapidly assess the toxicity of ARD-affected waters and sediments and to differentiate this response from the effects of other pollutants, such as increased nutrients and salinity.

The first total synthesis of the marine fatty acid (+/-)-9-methoxypentadecanoic acid: a synthetic route towards mid-chain methoxylated fatty acids

The marine fatty acid (+/-)-9-methoxypentadecanoic acid was synthesized for the first time in seven steps (7.8% overall yield) starting from commercially available 9-decen-1-ol. The key step in the synthesis was the coupling of pentylmagnesium bromide with 1-benzyloxy-9,10-epoxydecane under 1,5-cyclooctadiene copper (I) chloride catalysis. Nuclear magnetic resonance data are provided for the first time for this type of methoxylated fatty acids and the synthetic approach utilized is of general applicability since it can be used in the synthesis of other mid-chain methoxylated fatty acids. This synthetic methodology should afford sufficient quantities of these fatty acids for biological evaluation. The spectral data obtained for the title compound will also be helpful in subsequent characterizations of other mid-chain methoxylated fatty acids using nuclear magnetic resonance spectroscopy.

New advances in the chemistry of methoxylated lipids

Methoxylated lipids have been reviewed emphasizing the alkylglycerol ethers and fatty acids bearing the methoxy group in the alkyl chain. The literature on methoxylated lipids and their derivatives has been divided into four main groups, namely 2-methoxylated alkyl glycerols, omega-methoxylated fatty acids, mid-chain methoxylated fatty acids, and alpha-methoxylated fatty acids. The natural occurrence, biological activity, and synthesis of this interesting group of lipids are discussed. Most of these compounds have been isolated from either bacterial or marine sources, but others are mainly of synthetic origin. Among the interesting biological activities displayed by these compounds the most important are antibacterial, antifungal, antitumor, and antiviral.

Characterization of microbial communities of biofilters by phospholipid fatty acid analysis and rRNA targeted oligonucleotide probes

The microbial community of a biofilter for waste gas treatment of an animal rendering plant was characterized by the analyses of the phospholipid fatty acids (PLFAs) of the filter material. For these analyses five samples of one filter were taken in intervals between one and two months. The main components of the PLFA profiles were straight chain saturated, monounsaturated and cyclopropyl fatty acids. Terminally branched and 10-methyl branched fatty acids were present in minor amounts. The structure and succession of the microbial community was interpreted by the presence and quantitative changes of diagnostic fatty acids. The stability of diagnostic fatty acids in relation to varying incubation parameters was tested for a number of bacterial isolates from biofilters representing different phylogenetic branches. For two samples, the data from the PLFA-analyses were compared with data obtained by hybridization with fluorescently labeled, rRNA-targeted oligonucleotide probes specific for the alpha-, beta- and gamma-subclass of the Proteobacteria, the Actinobacteria (Firmicutes with high G+C content) and the Firmicutes with low G+C content. These data indicated a dominating number of Proteobacteria (54% and 35% of DAPI-stained cells), in which the gamma-Proteobacteria represented the main fraction. Actinobacteria were detected in minor amounts, the number of Firmicutes with low G+C content was near the detection limit of the method. About half of the cells detected with a probe specific for Bacteria did not hybridize with the probes specific for the alpha-, beta- and gamma subclass of the Proteobacteria and the two subgroups of the Firmicutes. The results of both methods, the fluorescence in situ hybridization (FISH) and the PLFA analyses corresponded well and were best suited to confirm and complement each other.

Acid habituation of Escherichia coli and the potential role of cyclopropane fatty acids in low pH tolerance

A reversible adaptive tolerance to low pH termed 'acid habituation' is demonstrated for five strains of Escherichia coli. Superimposed upon the intrinsic acid tolerance of individual strains, acid habituation significantly enhances the survival of exponential phase cultures exposed to a lethal acid challenge (pH 3.0), and minimises inter-strain variability in acid tolerance. The fatty acid composition of acid habituated, non-habituated, and de-habituated exponential phase cultures is also reported. During acid habituation, monounsaturated fatty acids (16:1 omega 7c and 18:1 omega 7c) present in the phospholipids of E. coli are either converted to their cyclopropane derivatives (cy17:0 and cy19:0), or replaced by saturated fatty acids. The acid tolerance of individual strains of E. coli appears to be correlated with membrane cyclopropane fatty acid content and, thus, it is postulated that increased levels of cyclopropane fatty acids may enhance the survival of microbial cells exposed to low pH. The results presented illustrate the remarkable capacity of E. coli to adapt to environmental challenges, and have significant implications for the survival of spoilage and pathogenic bacteria, and hence for food safety.

Emission of Climate-Relevant Trace Gases and Succession of Microbial Communities during Open-Windrow Composting

Determination of different indicators of microbial biomass, community structure, and bioactivity by the fumigation extraction method, as well as determination of phospholipid fatty acids (PLFAs) and their subfractions and the measurement of trace gases, respectively, provides valuable information about microbial succession in composting processes. The emission rates of carbon dioxide (CO(inf2)), methane (CH(inf4)), and nitrous oxide (N(inf2)O) increased successively during compost maturation: initially in the presence of easily degradable nutrients, during high temperature, and after the temperature had cooled down, respectively. The emission rate patterns of these trace gases corresponded to the concentrations of PLFAs and their particular subfractions. (i) Similar to the CO(inf2) emission rates, microbial biomass estimations by fumigation extraction and by determination of the amount of total PLFAs showed a discontinuous decrease during the composting process, with a slight increase at the end of the observation period. (ii) An increase in ether lipids, indicating the enhanced presence of archaean methanogens, and an elevated CH(inf4) emission were observed at the same time. (iii) The period of enhanced N(inf2)O emission corresponded to the increase in beta and omega hydroxy fatty acids derived from the outer membrane. Additionally, the continuous increase in branched-chain fatty acids suggested an increase in gram-positive bacteria and actinomycetes, and the decrease in polyunsaturated fatty acids indicated a decrease in eukaryotic cells during the composting.

Characterization of Bacteria That Suppress Rhizoctonia Damping-Off in Bark Compost Media by Analysis of Fatty Acid Biomarkers

Examination of cucumber roots ( Cucumis sativus L.) grown in bark compost media and of the surrounding edaphic substrate showed profiles of polar lipid fatty acids commonly found in bacteria. The composition of fatty acids in these profiles differed significantly between roots grown in a medium naturally suppressive to Rhizoctonia damping-off and roots from a conducive medium. Cucumber roots from the suppressive medium had higher proportions of cis -vaccenic acid (18:1 ω 7 c ) and the iso-branched monoenoic fatty acid i17:1 ω 8 but lower proportions of several iso- and anteiso-branched fatty acids compared with roots from the conducive medium. The concentrations of the bacterial fatty acids were significantly lower in the surrounding media. However, the suppressive and conducive growth substrates had differences in the composition of the bacterial fatty acids similar to those found between the cucumber roots proper. These results suggest major differences in bacterial community composition between suppressive and conducive systems. Fatty acid analyses were also utilized to examine the effects on bacterial community composition of root colonization by Flavobacterium balustinum 299, a biocontrol agent. The concentration of the most prominent fatty acid in this bacterium, i17:1 ω 8, was increased on roots produced from inoculated seeds in a medium rendered suppressive by the treatment. This change was concomitant with a significant increase in the concentration of 18:1 ω 7 c , not present in the lipids of the antagonist, indicating a shift in the microflora from a conducive to a suppressive bacterial community.