Interactions Of Organisms Research Articles

Allelopathic effects and potential active substances of Ceratophyllum demersum L. on Chlorella vulgaris Beij.

Morphological responses of green algae to submerged macrophytes were rarely studied, and the potential active substances played roles in the interaction were little known previously. In the current work, according to acetone extract experiments, it was demonstrated that submerged macrophytes (Ceratophyllum demersum L.) could allelopathically inhibit the growth of Chlorella vulgaris Beij. and induce its colony formation, the effects of which were concentration dependent. Gas chromatography–mass spectrometry analysis revealed eight kinds of active substances from the C. demersum extracts, namely hexanoic acid, phthalic acid, octanedioic acid, butenoic acid, azelaic acid, palmitic acid, alpha linolenic acid and pentanedioic acid. Standard compound addition test indicated that palmitic acid and alpha linolenic acid might play important roles in the induction of colony formation and growth inhibition of C. vulgaris. This study provided some more new insights into the photosynthetic organism interaction between submerged macrophytes and green algae, in terms of not only growth but also morphological responses.

The World Still Is Not Flat: Lessons Learned from Organismal Interactions with Environmental Heterogeneity in Terrestrial Environments.

Over the past decade, ecologists and physiologists alike have acknowledged the importance of environmental heterogeneity. Meaningful predictions of the responses of organisms to climate will require an explicit understanding of how organismal behavior and physiology are affected by such heterogeneity. Furthermore, the responses of organisms themselves are quite heterogeneous: physiology and behavior vary over different time scales and across different life stages, and because physiological systems do not operate in isolation of one another, they need to be considered in a more integrated fashion. Here, we review case studies from our laboratories to highlight progress that has been made along these fronts and generalizations that might be made to other systems, particularly in the context of predicting responses to climate change.

Adaptation and Evolution of Biological Materials.

Research into biological materials often centers on the impressive material properties produced in Nature. In the process, however, this research often neglects the ecologies of the materials, the organismal contexts relating to how a biological material is actually used. In biology, materials are vital to organismal interactions with their environment and their physiology, and also provide records of their phylogenetic relationships and the selective pressures that drive biological novelties. With the papers in this symposium, we provide a view on cutting-edge work in biological materials science. The collected research delivers new perspectives on fundamental materials concepts, offering surprising insights into biological innovations and challenging the boundaries of materials' characterization techniques. The topics, systems, and disciplines covered offer a glimpse into the wide range of contemporary biological materials work. They also demonstrate the need for progressive "whole organism thinking" when characterizing biological materials, and the importance of framing biological materials research in relevant, biological contexts.

Cry2A rice did not affect the interspecific interactions between two rice planthoppers, Nilaparvata lugens, and Sogatella furcifera

ABSTRACTInterspecific interactions are complex in agro-ecosystems and could be affected by agricultural technologies including transgenic crop planting. Few studies focused on the effects of Bt crops on the interspecific interactions of non-target organisms. Here we assessed the effects of transgenic cry2A rice (Cry2A rice) on the interspecific interaction between two rice planthoppers, namely, Nilaparvata lugens (the brown planthopper, BPH) and Sogatella furcifera (the white-backed planthopper, WBPH). Cry2A rice showed no significant effects on most biological parameters of these two rice planthoppers, except for wet weight of BPH female adults and development duration of WBPH female nymphs. In contrast, interspecific interactions between BPH and WBPH showed significant impacts on their biological parameters, no matter on Cry2A rice or non-transgenic control. In two-factor analysis combing rice line and interspecific interaction together, the interaction between these two factors did not affect most biological parameters of neither planthopper species, except for development duration of BPH female nymphs and WBPH nymphs (both male and female). Additionally, the egg distributions of BPH and WBPH had no significant differences between Cry2A and non-Cry2A treatments. Results of field experiments showed that Cry2A rice did not affect their population densities at most sampling dates in a five-year survey, and the interaction between BPH and WBPH showed no significant differences in both Cry2A and non-Cry2A rice paddies. In conclusion, our tested Cry2A rice would not affect the interspecific interactions between BPH and WBPH based both laboratory and field results.

ANTIMICROBIAL PROPERTIES OF BIOGENIC VOLATILE ORGANIC COMPOUNDS FROM TREE PLANTS

The article analyzes and summarizes scientific sources about the antimicrobial properties of phytoncides of common tree plants, the possibilities of rational use of them for preservation and improvement of human health and optimization of the microbial composition of the air environment. It has been discovered that the study of biogenic volatile organic compounds of plant origin has attracted the attention of many scholars of the last decades for the purpose of their wide use in various spheres of the national economy, particularly in medicine.It is noted that in the process of life higher plants release volatile organic substances that are one of the factors of natural immunity of plants, regulators of the sanitary state of the biosphere, play a significant role in the interaction of organisms in urbanized phytocoenoses, maintaining the balance of pathogenic microflora in atmospheric air of an urbanized ecosystem and residential apartments. Phytoncides are a mean of prevention and therapy a number of diseases, because when they enter the human body, they actively influence on different groups of microorganisms (Staphylococcus aureus, Bacillus subtilis, Esсherichia coli, Corynebacterium diphtheriae, Bordetella pertussis, Paramaecium caudatum, Stillonima millibus, etc.), which are the causative agents of bacterial, viral, fungal or protozoal infections.Many scientists have proven that volatile organic compounds of plant origin varies by their chemical composition and power of action, while the degree of their antimicrobial activity depends not only on the species belonging of plants and the phenological phase of seasonal development, but also on the vital state of the plant organism, meteorological conditions.Analysis of literary sources showed that all species of coniferous plants (in particular, genera Abies, Pínus, Picea, etc.) are characterized by high bactericidality of primary and secondary phytoncides, and among the deciduous ones it is necessary to note the following species: Betula pendula Roth, Padus avium Mill., Morus alba L., Acer platanoides L., A. pseudoplatanus L., Syringa vulgaris L., Ulmus pumila L., Vaccіnium vіtis-idaеa e L., tc. Such species, as Populus bolleana Lauche, Salix alba L., Quercus robur L., Sorbus aucuparia L., Spiraea×vanhouttei (Briot) Carrière, Viburnum opulus L., Aesculus hippocastanum L., Fraxinus excelsior L., Tillia cordata Mill., which possess both secondary and primary volatile secretions, are characterized by medium antimicrobial action.

Laser ablation tomography for visualization of root colonization by edaphic organisms.

Soil biota have important effects on crop productivity, but can be difficult to study in situ. Laser ablation tomography (LAT) is a novel method that allows for rapid, three-dimensional quantitative and qualitative analysis of root anatomy, providing new opportunities to investigate interactions between roots and edaphic organisms. LAT was used for analysis of maize roots colonized by arbuscular mycorrhizal fungi, maize roots herbivorized by western corn rootworm, barley roots parasitized by cereal cyst nematode, and common bean roots damaged by Fusarium. UV excitation of root tissues affected by edaphic organisms resulted in differential autofluorescence emission, facilitating the classification of tissues and anatomical features. Samples were spatially resolved in three dimensions, enabling quantification of the volume and distribution of fungal colonization, western corn rootworm damage, nematode feeding sites, tissue compromised by Fusarium, and as well as root anatomical phenotypes. Owing to its capability for high-throughput sample imaging, LAT serves as an excellent tool to conduct large, quantitative screens to characterize genetic control of root anatomy and interactions with edaphic organisms. Additionally, this technology improves interpretation of root–organism interactions in relatively large, opaque root segments, providing opportunities for novel research investigating the effects of root anatomical phenes on associations with edaphic organisms.

Phenotypic niche partitioning and transcriptional responses of Microcystis aeruginosa in a spatially heterogeneous environment

Variant morphotypes (smooth; S-type and wrinkled; W-type cells) of Microcystis aeruginosa KW strain were observed in bloom samples and during the cultivation of cells in static broth cultures. RNA-seq based whole transcriptome sequencing was performed to examine the pattern of gene expression in these morphotypes. In total 493 differentially expressed transcripts were identified between the two morphotypes. Genes involved in photosynthesis, photosynthesis-related antenna proteins and oxidative phosphorylation were significantly upregulated in W-type cells relative to the control (S-type cells). Here we discussed the roles of these genes and showed that M. aeruginosa responds and acclimates to subtle variations in environmental parameters, especially light, through alteration of the transcript levels of relevant genes. Furthermore, additional physiological experiments such as analyses of photosynthetic activity, redox state and exopolysaccharide production provided further evidence and confirmed the validity of the transcriptomic results. The findings of this study provide greater insight into the metabolic pathways and complex mechanisms that may regulate the interaction and niche adaptation of this important bloom-forming organism in fluctuating environmental conditions.

Collaborative involvement of woody plant roots and rhizosphere microorganisms in the formation of pedogenetic clays.

Previous studies have described the laying down of specific B horizons in south-western Australian ecosystems. This paper presents biomolecular, morphological and physicochemical analyses elucidating the roles of specific woody plant taxa and rhizosphere bacteria in producing these phenomena. Clayey deposits within lateral root systems of eucalypts and appropriate background soil samples were collected aseptically at multiple locations on sand dunes flanking Lake Chillinup. Bacterial communities were profiled using tagged next-generation sequencing (Miseq) of the 16S rRNA gene and assigned to operational taxonomic units. Sedimentation, selective dissolution and X-ray diffraction analyses quantitatively identified clay mineral components. Comparisons were made of pedological features between the above eucalypt systems, giant podzols under proteaceous woodland on sand dunes at the study site of Jandakot and apparently similar systems observed elsewhere in the world. Bacterial communities in clay pods are highly diverse, resolving into 569 operational taxonomic units dominated by Actinobacteria at 38.0-87.4 % of the total reads. Multivariate statistical analyses of community fingerprints demonstrated substrate specificity. Differently coloured pods on the same host taxon carry distinctive microfloras correlated to diversities and abundances of Actinobacteria, Acidobacteria, Firmicutes and Proteobacteria. A number of these microbes are known to form biominerals, such as phyllosilicates, carbonates and Fe-oxides. A biogenic origin is suggested for the dominant identified mineral precipitates, namely illite and kaolinite. Comparisons of morphogenetic features of B horizons under eucalypts, tree banksias and other vegetation types show remarkably similar developmental trajectories involving pods of precipitation surrounding specialized fine rootlets and their orderly growth to form a continuous B horizon. The paper strongly supports the hypothesis that B-horizon development is mediated by highly sophisticated interactions of host plant and rhizosphere organisms in which woody plant taxa govern overall morphogenesis and supply of mineral elements for precipitation, while rhizosphere microorganisms execute biomineralization processes.

Whole-body spatially-resolved metabolomics method for profiling the metabolic differences of epimer drug candidates using ambient mass spectrometry imaging

Investigation of the in vivo drug action and metabolic differences of epimer drugs is challenging. Whole-body MSI analysis can visually present the stereoscopic distribution of molecules related to the interaction of drugs and organisms, and can provide more comprehensive organ-specific profiling information. Herein, we developed a whole-body spatially-resolved imaging metabolomics method based on an air flow-assisted ionisation desorption electrospray ionisation (AFADESI)-MSI system coupled with a high-resolution mass spectrometer and highly discriminating imaging software. The epimeric sedative-hypnotic drug candidates YZG-331 and YZG-330 were selected as examples, and rats administered normal or high oral doses were used. By performing multivariate statistical data-mining on the combined MSI data, organ-specific differential ions were screened. By comparing the variations in the relative contents of the drugs, their metabolites, and endogenous neurotransmitters throughout whole-body tissue sections of the rats, rich information that could potentially explain the more significant sedative-hypnotic effects of YZG-330 compared to YZG-331 was obtained. Such as the increased ratio of gamma-aminobutyric acid in the brain and stomach of the rats (0.25, 0.47, 0.68, 0.30, and 0.89 for the control and YZG-331-H, YZG-330-H, YZG-331-L, and YZG-330-L, respectively) were interesting. This study provided a convenient and visual method to investigate in vivo molecular metabolic differences and provide insight towards a better understanding of the pharmacodynamic mechanisms of these sedative-hypnotic drug-candidates.

Fungi in aquatic ecosystems.

Fungi are phylogenetically and functionally diverse ubiquitous components of almost all ecosystems on Earth, including aquatic environments stretching from high montane lakes down to the deep ocean. Aquatic ecosystems, however, remain frequently overlooked as fungal habitats, although fungi potentially hold important roles for organic matter cycling and food web dynamics. Recent methodological improvements have facilitated a greater appreciation of the importance of fungi in many aquatic systems, yet a conceptual framework is still missing. In this Review, we conceptualize the spatiotemporal dimensions, diversity, functions and organismic interactions of fungi in structuring aquatic food webs. We focus on currently unexplored fungal diversity, highlighting poorly understood ecosystems, including emerging artificial aquatic habitats.

Response of bleached and symbiotic sea anemones to plastic microfiber exposure

Microplastics are emerging contaminants in the marine environment. They enter the ocean in a variety of sizes and shapes, with plastic microfiber being the prevalent form in seawater and in the guts of biota. Most of the laboratory experiments on microplastics has been performed with spheres, so knowledge on the interactions of microfibers and marine organisms is limited. In this study we examined the ingestion of microfibers by the sea anemone Aiptasia pallida using three different types of polymers: nylon, polyester and polypropylene. The polymers were offered to both symbiotic (with algal symbionts) and bleached (without algal symbionts) anemones. The polymers were introduced either alone or mixed with brine shrimp homogenate. We observed a higher percentage of nylon ingestion compared to the other polymers when plastic was offered in the absence of shrimp. In contrast, we observed over 80% of the anemones taking up all types of polymers when the plastics were offered in the presence of shrimp. Retention time differed significantly between symbiotic and bleached anemones with faster egestion in symbiotic anemones. Our results suggest that ingestion of microfibers by sea anemones is dependent both on the type of polymers and on the presence of chemical cues of prey in seawater. The decreased ability of bleached anemones to reject plastic microfiber indicates that the susceptibility of anthozoans to plastic pollution is exacerbated by previous exposure to other stressors. This is particularly concerning given that coral reef ecosystems are facing increases in the frequency and intensity of bleaching events due to ocean warming.

Interactions in self-assembled microbial communities saturate with diversity

How the diversity of organisms competing for or sharing resources influences community function is an important question in ecology but has rarely been explored in natural microbial communities. These generally contain large numbers of species making it difficult to disentangle how the effects of different interactions scale with diversity. Here, we show that changing diversity affects measures of community function in relatively simple communities but that increasing richness beyond a threshold has little detectable effect. We generated self-assembled communities with a wide range of diversity by growth of cells from serially diluted seawater on brown algal leachate. We subsequently isolated the most abundant taxa from these communities via dilution-to-extinction in order to compare productivity functions of the entire community to those of individual taxa. To parse the effect of different types of organismal interactions, we defined relative total function (RTF) as an index for positive or negative effects of diversity on community function. Our analysis identified three overall regimes with increasing diversity. At low richness (<12 taxa), positive and negative effects of interactions were both weak, while at moderate richness (12–26 taxa), community resource uptake increased but the carbon use efficiency decreased. Finally, beyond 26 taxa, the effect of interactions on community function saturated and further diversity increases did not affect community function. Although more diverse communities had overall greater access to resources, on average individual taxa within these communities had lower resource availability and reduced carbon use efficiency. Our results thus suggest competition and complementation simultaneously increase with diversity but both saturate at a threshold.

Inverse Correlation between Lethality and Thermodynamic Stability of Contact Insecticide Polymorphs

Contact insecticides often involve the interaction of whole organisms and toxicant crystal surfaces. The crystalline phase of these compounds has not, however, been considered for the optimization of insecticide performance. Lindane (1R,2r,3S,4R,5r,6S-hexachlorocyclohexane) has been one of the most widely used insecticides, but other (inactive) stereoisomers accompanying its manufacture have led to massive chemical waste remediation problems. Crystalline polymorphs are also isomers in the broadest sense, yet only one crystal structure of lindane has been reported. Herein, we report the discovery and characterization of two new polymorphs, Forms II and III. The efficacy of Forms I, II, and III against Drosophila melanogaster revealed an inverse correlation between lethality and thermodynamic stability; the least stable kills fastest. This understanding provides a crystal engineering opportunity wherein formulations containing the most active contact insecticide polymorph can achieve infectious disease prop...

Soil Metagenome of Tropical White Sand Heath Forests in Borneo: What Functional Traits Are Associated with an Extreme Environment Within the Tropical Rainforest?

White sand heath forests (WS) or kerangas, an unusual variant of tropical forests in Borneo, characterized by open scrubby vegetation, low productivity, and distinctive plant species composition and soil microbial community, are regarded as a stressful low-pH and/or nutrient environment. We investigated whether the functional soil metagenome also shows a predicted set of indicators of stressful conditions in WS. Based on stress-tolerant strategies exhibited by larger organisms, we hypothesized that genes for stress tolerance, dormancy, sporulation, and nutrient processing are more abundant in the soil microbiota of WS. We also hypothesized that there is less evidence of biotic interaction in white sand soils, with lower connectivity and fewer genes related to organismic interactions. In Brunei, we sampled soils from a WS and a normal primary dipterocarp forest, together with an inland heath, an intermediate forest type. Soil DNA was extracted, and shotgun sequencing was performed using Illumina HiSeq platform, with classification by the Metagenomics Rapid Annotation using Subsystem Technology (MG-RAST). The results, on one hand, supported our hypothesis (on greater abundance of dormancy, virulence, and sporulation-related genes). However, some aspects of our results showed no significant difference (specifically in stress tolerance, antibiotic resistance, viruses, and clustered regularly interspaced short palindrome repeats (CRISPRs)). It appears that in certain respects, the extreme white sand environment produces the predicted strategy of less biotic interaction, but exhibits high soil microbiota connectivity and functional diversity.

Burrowing macroinvertebrates alter phosphorus dynamics in drainage ditch sediments

Consumptive and nonconsumptive interactions of benthic organisms play important roles in regulating rates of ecosystem services such as nutrient cycling in freshwater ecosystems. Studies of macroinvertebrate communities in drainage ditches have focused on documenting the biodiversity supported by these human-altered environments, but none have explored the ecosystem functions provided by those biological communities in ditches. Bioturbation by burrowing benthic invertebrates in ditch sediments may change rates of biogeochemical processes controlling fluxes of nutrients across the sediment–water interface. We used microcosms to test the effect of four species of burrowing invertebrates (Naididae: Ilyodrilus templetoni, Naididae: Limnodrilus hoffmeisteri, Gammaridae: Crangonyx sp., Chironomidae: Chironomus decorus S.G.) on exchanges of phosphorus between sediment and water from a drainage ditch. These effects were measured across a range of sediment and water characteristics, representing variability within ditches. All species reduced concentrations of P (as molybdenum-reactive phosphorus) in the surface water relative to controls under conditions were sediment porewater was not likely to contain higher concentrations of P than surface water. Decreases in P concentration were linked to changes in the sediment redox potential and water pH. Two species (L. hoffmeisteri and C. decorus) increased P concentrations under conditions where sediment porewater likely had higher concentrations of P than surface water. Increases in P concentrations were likely due to physical changes to the sediment from burrowing, and increased transport of dissolved P from sediment porewater to surface waters. Management of ditches should consider effects of burrowing benthic invertebrates on physical and biogeochemical processes at the sediment–water interface. Habitat manipulation in ditches could lead to unpredicted changes in nutrient dynamics mediated by changes to the burrowing benthic invertebrate community.

Mother-fetus immunogenetic dialogue as a factor of progeny immune system development

Despite the advances in medicine, about 4 million children under the age of 6 months die annually around the world due to infection, which is 450 deaths per hour (UNISEF, 2009). The degree of development of the immune system of children born in time is determined by many factors, including the immunogenetic similarity or difference of mother and fetus organisms, which, in turn, is due to the genotypes of mating pairs, as well as the selection of surrogate mothers duringin vitrofertilization. From our review of the literature, it follows that immunogenetic interactions of mother and fetus organisms, which occur at all stages of pre- and postnatal development, have a signifcant effect on the resistance of offspring to infections and allergens. Before implantation, the mother’s immune responses are formed under the influence of semen fluid antigens, leukocytes and cytokines, as well as under the influence of the genes of the major histocompatibility complex, which are expressed in embryos at the stage of two cells. After implantation, transplacental transfer of immunoglobulins and immunocompetent cells becomes of immunomodulating importance. It is important to emphasize that, although substances with a high molecular weight usually do not pass through the placenta, this rule does not apply to immunoglobulin G (IgG), which, with a molecular weight of about 160 kDa, overcomes the transplacental barrier due to binding to the fetal Fc receptor. The level of IgG in newborns usually correlates with the level of maternal antibodies. During the period of natural feeding, the immune protection of newborns is provided by the mechanisms of innate immunity and the factors of humoral immunity of mothers. It has been shown that immunoglobulins from the milk of many animal species are transferred through the neonatal intestinal epithelium to the blood. Since breast milk contains large amounts of various immunoactive components, including proteins, cytokines, hormones, immunoglobulins, exosomes containing micro-RNA, and viable immune cells, the immunomodulating effects of breast milk persist even after elimination of maternal immunoglobulins from the blood of the offspring, up to maturation. Analysis of a large body of experimental data shows that the study of mechanisms of “motherfetus” and “mother-newborn” interactions are the basis of a knowledge base needed to fnd means of life-long directed modulation of the descendants’ immune status.

INFLUENCE OF LOCAL CRUSTAL HETEROGENEITY ON THE RESIDENTS’ MORBIDITY OF THE NORTHERN URBANIZED TERRITORIES

The aim: to reveal the influence of local crustal heterogeneity peculiarities on the course of visceral diseases in the conditions of the northern urbanized territory in the context of Surgut city. Methods. Frequency of patients' medical aid appealability depending on their residence - upper local crustal heterogeneity or upper solid was studied. Besides, comparative average monthly frequency of patients' appealability with acute coronary syndrome and acute cerebrovascular accident, residents of upper local crustal heterogeneity or upper solid was also studied. Medical records of 6 932 patients were analyzed (cardiovascular diseases included). Results. A significant predominance of frequency of appealability among patients with cerebrovascular accident (in 1,5 times), angor pectoris (in 1,4 times), myocardial infarction (in 1,4 times), hypertensive disease attack (in 1,3 times) (p &lt; 0,001), living in the zones of local crustal heterogeneity in comparison with those living upper solid was revealed. Frequency of patients' appealability with acute coronary syndrome and acute cerebrovascular accident living upper local crustal heterogeneity prevails in the periods of geomagnetic activity increase (p &lt; 0,05 and p &lt; 0,01 respectively). Conclusions. Negative effect of geomagnetic field of the Earth's fault zones on cardiovascular system morbidity of the population was revealed. The results of the carried out medico-ecological study open a prospect for a more enhanced study of the ecologically dependent public health from a new perspective of the organism's interaction with geophysical factors.

Biological interactions mediate context and species-specific sensitivities to salinity.

Toxicants have both sub-lethal and lethal effects on aquatic biota, influencing organism fitness and community composition. However, toxicant effects within ecosystems may be altered by interactions with abiotic and biotic ecosystem components, including biological interactions. Collectively, this generates the potential for toxicant sensitivity to be highly context dependent, with significantly different outcomes in ecosystems than laboratory toxicity tests predict. We experimentally manipulated stream macroinvertebrate communities in 32 mesocosms to examine how communities from a low-salinity site were influenced by interactions with those from a high-salinity site along a gradient of salinity. Relative to those from the low-salinity site, organisms from the high-salinity site were expected to have greater tolerance and fitness at higher salinities. This created the potential for both salinity and tolerant-sensitive organism interactions to influence communities. We found that community composition was influenced by both direct toxicity and tolerant-sensitive organism interactions. Taxon and context-dependent responses included: (i) direct toxicity effects, irrespective of biotic interactions; (ii) effects that were owing to the addition of tolerant taxa, irrespective of salinity; (iii) toxicity dependent on sensitive-tolerant taxa interactions; and (iv) toxic effects that were increased by interactions. Our results reinforce that ecological processes require consideration when examining toxicant effects within ecosystems.This article is part of the theme issue 'Salt in freshwaters: causes, ecological consequences and future prospects'.

Exploring variation in phyllosphere microbial communities across four hemlock species

AbstractThe hemlock woolly adelgid (HWA) is an insect native to Asia and likely western North America. First reported in eastern North America in 1951, it has devastated eastern hemlock (Tsuga canadensis) populations. Loss of hemlock will greatly affect the structure and function of eastern forests. Susceptibility to adelgid infestation varies within eastern hemlocks and across other hemlock species. Our study was conducted to determine whether eastern hemlocks share a similar stem (phyllosphere) microbial community with other co‐occurring hemlocks and whether community‐level shifts are associated within trees of the same species based on HWA infestation. Surprisingly, we found no difference in microbial community composition or diversity between trees of the same species based on the level of HWA infestation. However, microbial communities varied significantly across the four hemlock trees sampled, native T. canadensis and three non‐natives: Tsuga chinensis, Tsuga dumosa, and Tsuga sieboldii. Within these tree hosts, microbial communities from T. dumosa and T. chinensis clustered together, and microbial communities from T. canadensis and T. sieboldii clustered separately from all other tree species. Additionally, specific indicator taxa were identified for all the tree species sampled. These results indicate that Asian hemlocks might not fill the same niche in eastern forests as the native eastern hemlock. Further work should be conducted to determine how differences in hemlock species and associated microbial communities might scale up to alter organismal interactions involving hemlocks.

2397. Comparing Predictive Performance of INCREMENT Scores on Mortality Among Patients With Carbapenem-Non-Susceptible (CNS) Klebsiella pneumoniae (Kp) and Enterobacter cloacae Complex (Ecc) Bloodstream Infections (BSI) in the Veterans Health Administration (VHA)

BackgroundINCREMENT is an international collaborative study of BSI caused by extended-spectrum β-lactamase (ESBL) or carbapenemase-producing Enterobacteriaceae (CPE) that has developed and validated predictive models for mortality. Most CNS Enterobacteriaceae BSI in the VHA are either Klebsiella pneumoniae (Kp) or Enterobacter cloacae complex (Ecc). We applied the INCREMENT score for CPE to predict mortality in patients with CNS-Kp and CNS-Ecc BSIs in the VHA and compared the distribution and predictive performance of the score across organisms.MethodsUsing nationwide VHA databases, unique patients in the continental United States with Kp or Ecc BSI post 48 hours of hospitalization from 2006 to 2015 were identified. Isolates with intermediate susceptibility or resistance to any tested carbapenem were considered non-susceptible. We used databases and medical records to obtain clinical characteristics, treatment, and outcomes, and applied INCREMENT criteria and definitions to calculate a prediction score. We compared the distribution of the scores by organism and used receiver operating curve methods to compare predictive performance between Kp and Ecc BSI.ResultsWe identified 57 patients with CNS-Ent and 140 with CNS-Kp BSI. The demographics and infection characteristics were highly consistent across organisms, both afflicting patients who were predominantly male, older and chronically ill. Mortality at 14 days was 39% in CNS-Ecc and 38% in CNS-Kp. Similar proportions (65% of Ecc and 68% of Kp) met the criteria for an INCREMENT score: monomicrobial and alive over 48 hours after culture specimen. The distribution of scores was similar within mortality outcomes across organisms, with the highest scores observed in Kp patients who died (Figure 1). The ROC areas under the curve were 0.71 for CNS-Ecc and 0.75 for CNS-Kp (Figure 2). A multivariable logistic model predicting mortality detected neither an organism effect nor an interaction of organism and INCREMENT score.ConclusionThe INCREMENT score, validated in a CPE cohort predominantly comprised of Kp, performed similarly well across CNS-Ent and CNS-Kp patients in our cohort. This suggests the model is robust to CNS organisms of undetermined resistance mechanism and that the association between INCREMENT and mortality is consistent across Kp and Ecc. Disclosures All authors: No reported disclosures.