Bacterial treatments inoculated onto the <i>Acropora palmata</i> fragments in the challenge experiments.

<p>Eight isolates of <i>Serratia marcescens</i> representing three pulsed-field gel electrophoresis (PFGE) strains (PDR60, PDL100, and WWI31) were used. The source, location, and date of collection are included for each treatment.</p

Time series of white pox affected <i>Acropora palmata</i> at Looe Key Reef in the Florida Keys and average time to tissue loss in the challenge experiments.

<p>A. Images of white pox affected <i>A. palmata</i> at Looe Key, from June 2008, to June 2009, to July 2009 (left to right), show colony growth and partial mortality. Scales bars are 3 cm on a side or 3 cm in diameter. (Photographs by JW Porter and MK Meyers) B. Average time (days) to development of disease signs on <i>A. palmata</i> inoculated with <i>Serratia marcescens</i>. Days to tissue loss was averaged for the three <i>A. palmata</i> fragments used in each treatment and each control. The original inoculum was recovered for all seven of the presented <i>S. marcescens</i> inocula, including five isolates of strain PDR60 collected from acroporid serratiosis (APS)-affected <i>A. palmata</i> (isolates 1, 2), non-host coral <i>Siderastrea siderea</i> (isolate 4), corallivorous snail <i>Coralliophila abbreviata</i> (isolate 5), and untreated wastewater (isolate 6). Two additional inocula included <i>S. marcescens</i> strain PDL100 (isolate 7), previously confirmed as an APS pathogen through fulfillment of Koch's Postulates (2) and <i>S. marcescens</i> strain WWI31 from untreated wastewater (isolate 8). The vehicle control exhibited tissue loss beginning at day 15. The <i>E. coli</i>-plus-vehicle control and the isolate 3-plus-vehicle treatment did not exhibit tissue loss and remained apparently healthy for the duration of the 26 day study. Virulent strains (isolates 1, 2, 5, 6, 8) caused tissue loss within 14 days of inoculation and attenuated strains (isolates 4, 7) caused tissue loss after day 14.</p

Treatments and controls used in the challenge experiments.

<p>A total of eleven challenge experiments were conducted each within a single aquarium and each with three <i>Acropora palmata</i> coral fragments (F1, F2, F3). Coral colony of origin and number of days to tissue loss is included for each coral fragment. Treatments and controls for which there was no tissue loss are also noted.</p

<i>Acropora palmata</i> colonies used in the challenge experiments.

<p>Number of fragments per <i>A. palmata</i> colony, the challenge for each fragment (control or inoculation with a <i>Serratia marcescens</i> test isolate), and the result of each challenge (tissue loss or no tissue loss) are included. Three coral fragments (F1, F2, F3) were used for each challenge.</p

Spatial Homogeneity of Bacterial Communities Associated with the Surface Mucus Layer of the Reef-Building Coral <i>Acropora palmata</i>

<div><p>Coral surface mucus layer (SML) microbiota are critical components of the coral holobiont and play important roles in nutrient cycling and defense against pathogens. We sequenced 16S rRNA amplicons to examine the structure of the SML microbiome within and between colonies of the threatened Caribbean reef-building coral <i>Acropora palmata</i> in the Florida Keys. Samples were taken from three spatially distinct colony regions—uppermost (high irradiance), underside (low irradiance), and the colony base—representing microhabitats that vary in irradiance and water flow. Phylogenetic diversity (PD) values of coral SML bacteria communities were greater than surrounding seawater and lower than adjacent sediment. Bacterial diversity and community composition was consistent among the three microhabitats. Cyanobacteria, Bacteroidetes, Alphaproteobacteria, and Proteobacteria, respectively were the most abundant phyla represented in the samples. This is the first time spatial variability of the surface mucus layer of <i>A</i>. <i>palmata</i> has been studied. Homogeneity in the microbiome of <i>A</i>. <i>palmata</i> contrasts with SML heterogeneity found in other Caribbean corals. These findings suggest that, during non-stressful conditions, host regulation of SML microbiota may override diverse physiochemical influences induced by the topographical complexity of <i>A</i>. <i>palmata</i>. Documenting the spatial distribution of SML microbes is essential to understanding the functional roles these microorganisms play in coral health and adaptability to environmental perturbations.</p></div

Regions of the surface mucus layer (SML) sampled (uppermost, underside, base) from <i>A</i>. <i>palmata</i>.

<p>Regions of the surface mucus layer (SML) sampled (uppermost, underside, base) from <i>A</i>. <i>palmata</i>.</p

Principal coordinate analysis of beta-diversity metrics among microbial samples from <i>A</i>. <i>palmata</i>.

<p>Samples are coded by source tissue or environment (base, underside, uppermost, reef seawater, and sediment).</p

Microbial diversity in different regions of the SML of <i>A</i>. <i>palmata</i> (n = 3–4; 11 samples), reef seawater (n = 4), and adjacent sediment (n = 2).

<p>Microbial diversity in different regions of the SML of <i>A</i>. <i>palmata</i> (n = 3–4; 11 samples), reef seawater (n = 4), and adjacent sediment (n = 2).</p

Biodegradation of Poly(3-hydroxybutyrate-<i>co</i>-3-hydroxyhexanoate) Plastic under Anaerobic Sludge and Aerobic Seawater Conditions: Gas Evolution and Microbial Diversity

Poly­(3-hydroxybutyrate-<i>co</i>-3-hydroxyhexanoate) (poly­(3HB-<i>co</i>-3HHx)) thermoplastics are a promising biodegradable alternative to traditional plastics for many consumer applications. Biodegradation measured by gaseous carbon loss of several types of poly­(3HB-<i>co</i>-3HHx) plastic was investigated under anaerobic conditions and aerobic seawater environments. Under anaerobic conditions, the biodegradation levels of a manufactured sheet of poly­(3HB-<i>co</i>-3HHx) and cellulose powder were not significantly different from one another over 85 days with 77.1 ± 6.1 and 62.9 ± 19.7% of the carbon converted to gas, respectively. However, the sheet of poly­(3HB-<i>co</i>-3HHx) had significantly higher methane yield (<i>p</i> ≤ 0.05), 483.8 ± 35.2 mL·g^–1 volatile solid (VS), compared to cellulose controls, 290.1 ± 92.7 mL·g^–1 VS, which is attributed to a greater total carbon content. Under aerobic seawater conditions (148–195 days at room temperature), poly­(3HB-<i>co</i>-3HHx) sheets were statistically similar to cellulose for biodegradation as gaseous carbon loss (up to 83% loss in about 6 months), although the degradation rate was lower than that for cellulose. The microbial diversity was investigated in both experiments to explore the dominant bacteria associated with biodegradation of poly­(3HB-<i>co</i>-3HHx) plastic. For poly­(3HB-<i>co</i>-3HHx) treatments, <i>Cloacamonales</i> and <i>Thermotogales</i> were enriched under anaerobic sludge conditions, while <i>Clostridiales</i>, <i>Gemmatales</i>, <i>Phycisphaerales</i>, and <i>Chlamydiales</i> were the most enriched under aerobic seawater conditions

Map of sampling areas in the Oconee River watershed (near Athens in the Piedmont physiographic province) and Little River watershed (near Tifton in the Coastal Plain physiographic province).

<p>Base map source: U.S. Geological Survey, Department of the Interior. (<a href="http://water.usgs.gov/lookup/getspatial?physio" target="_blank">http://water.usgs.gov/lookup/getspatial?physio</a>). Background: watershed produced using ESRI-ArcGIS (LM_LICENSE_FILE: <a href="mailto:[email protected]" target="_blank">[email protected]</a>) based on U.S Geological Survey, National Elevation Dataset (NED), 2012. Site location: Department of Environmental Health Science-UGA. (Produced by Presotto A, 2015).</p