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Colonization by fragments of the submerged macrophyte Myriophyllum spicatum under different sediment type and density conditions.

ABSTRACT: In this paper, the effect of plant density, sediment type, and macrophyte fragment size on the fragment colonization ability of Myriophyllum spicatum was evaluated in an outdoor experiment. The relative growth rate (RGR) was higher in the mud and low-density treatments than in the sand and high-density treatments. The relative elongation rate (RER) decreased with increasing density and fragment size, with RER values being much higher in the mud than the sand treatments. Both branching number and shoot diameter increased with decreasing density and increasing fragment size, and were significantly higher in the mud than the sand treatments. The shoot : root ratio was higher in the mud treatments than in the sand treatments. Total N content in both the shoot and root was significantly higher in the mud and low-density treatments than in the sand and high-density treatments. Shoot P content only decreased with increasing density, while root P content was higher in the mud and low-density treatments than in the sand and high-density treatments. These data indicate that fragment colonization by M. spicatum is improved by large fragments, low density, and nutrient-rich sediments, and that these conditions contribute to the rapid population expansion of this species.

SUBMITTER: Li F

PROVIDER: S-EPMC4488764 | biostudies-other | 2015

REPOSITORIES: biostudies-other

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Project description:BackgroundSynthetic microplastics (≤5-mm fragments) are emerging environmental contaminants that have been found to accumulate within coastal marine sediments worldwide. The ecological impacts and fate of microplastic debris are only beginning to be revealed, with previous research into these topics having primarily focused on higher organisms and/or pelagic environments. Despite recent research into plastic-associated microorganisms in seawater, the microbial colonization of microplastics in benthic habitats has not been studied. Therefore, we employed a 14-day microcosm experiment to investigate bacterial colonization of low-density polyethylene (LDPE) microplastics within three types of coastal marine sediment from Spurn Point, Humber Estuary, U.K.ResultsBacterial attachment onto LDPE within sediments was demonstrated by scanning electron microscopy and catalyzed reporter deposition fluorescence in situ hybridisation (CARD-FISH). Log-fold increases in the abundance of 16S rRNA genes from LDPE-associated bacteria occurred within 7 days with 16S rRNA gene numbers on LDPE surfaces differing significantly across sediment types, as shown by quantitative PCR. Terminal-restriction fragment length polymorphism (T-RFLP) analysis demonstrated rapid selection of LDPE-associated bacterial assemblages whose structure and composition differed significantly from those in surrounding sediments. Additionally, T-RFLP analysis revealed successional convergence of the LDPE-associated communities from the different sediments over the 14-day experiment. Sequencing of cloned 16S rRNA genes demonstrated that these communities were dominated after 14 days by the genera Arcobacter and Colwellia (totalling 84-93% of sequences). Attachment by Colwellia spp. onto LDPE within sediments was confirmed by CARD-FISH.ConclusionsThese results demonstrate that bacteria within coastal marine sediments can rapidly colonize LDPE microplastics, with evidence for the successional formation of plastisphere-specific bacterial assemblages. Although the taxonomic compositions of these assemblages are likely to differ between marine sediments and the water column, both Arcobacter and Colwellia spp. have previously been affiliated with the degradation of hydrocarbon contaminants within low-temperature marine environments. Since hydrocarbon-degrading bacteria have also been discovered on plastic fragments in seawater, our data suggest that recruitment of hydrocarbonoclastic bacteria on microplastics is likely to represent a shared feature between both benthic and pelagic marine habitats.

Project description:Cordycepin is a crucial bioactive compound produced by the fungus Cordyceps spp. Its therapeutic potential has been recognized for a wide range of biological properties such as anticancer, anti-diabetic, antidepressant, antioxidant, immunomodulation, etc. Moreover, its human random clinical trials depicted a promising anti-inflammatory activity that reduced the airway inflammation remarkably in asthmatic patients. But its overexploitation and low production of cordycepin in naturally growing biomass are insufficient to meet its existing market demand for its therapeutic use. Therefore, strategies for enhancement of cordycepin production in Cordyceps spp. are warranted. However, specifically, wild type Ophiocordyceps sinensis possesses a very low content of cordycepin and has restricted growth in natural mycelial biomass. To overcome these limitations, this study attempted to enhance cordycepin production in its mycelial biomass in vitro under submerged conditions by adding various growth supplements. The effect of these growth supplements was evaluated by reversed-phase high-performance liquid chromatography (RP-HPLC) which demonstrated that among nucleosides- hypoxanthine and adenosine; amino acids-glycine and glutamine; plant hormones- 1-naphthaleneacetic acid (NAA) and 3-indoleacetic acid (IAA); vitamin-thiamine (B1) from each group of growth supplements yielded a higher amount of cordycepin with 466.48 ± 3.88, 380.23 ± 1.78, 434.97 ± 2.32, 269.78 ± 2.92, 227.61 ± 2.34, 226.02 ± 1.69 and 185.26 ± 2.35 mg/L respectively as compared to control with 13.66 ± 0.64 mg/L. Further, at the transcriptional level, quantitative real time-polymerase chain reaction (qRT-PCR) analysis of genes associated with metabolism and cordycepin biosynthesis depicted significant upregulation of major downstream genes- NT5E, RNR, purA, and ADEK which corroborated well with RP-HPLC analysis. Taken together, the present study identified growth supplements as potential precursors to activate the cordycepin biosynthesis pathway leading to improved cordycepin production in O. sinensis.

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Colonization by fragments of the submerged macrophyte Myriophyllum spicatum under different sediment type and density conditions.

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