Effect of Various Local Anthropogenic Impacts on the Diversity of Coral Mucus-Associated Bacterial Communities

The global continued decline in coral reefs is intensifying the need to understand the response of corals to local environmental stressors. Coral-associated bacterial communities have been suggested to have a swift response to environmental pollutants. This study aims to determine the variation in the bacterial communities associated with the mucus of two coral species, Pocillopora damicornis (Linnaeus, 1758) and Stylophora pistillata (Esper, 1792), and the coral-surrounding seawater from three areas exposed to contamination at the Jordanian coast of the Gulf of Aqaba (Red Sea), and also explores the antibacterial activity of these bacteria. Corals were collected from three contaminated zones along the coast, and the bacteria were quantified and identified by conventional morphological and biochemical tests, as well as 16S rRNA gene sequencing. The average number of bacteria significantly varied among the coral mucus from the sampling zones and between the coral mucus and the surrounding seawater. The P. damicornis mucus-associated bacterial community was dominated by members of the classes Gammaproteobacteria, Cytophagia, and Actinomycetia, while the mucus of S. pistillata represented higher bacterial diversity, with the dominance of the bacterial classes Gammaproteobacteria, Actinomycetia, Alphaproteobacteria, and Bacilli. The effects of local anthropogenic impacts on coral mucus bacterial communities were represented in the increased abundance of bacterial species related to coral diseases. Furthermore, the results demonstrated the existence of bacterial isolates with antibacterial activity that possibly acted as a first line of defense to protect and maintain the coral host against pathogens. Indeed, the dynamics of coral-associated microbial communities highlight the importance of holistic studies that focus on microbial interactions across the coral reef ecosystem

Centroceras gasparrinii subsp. minor subsp. nov. (Ceramiaceae, Rhodophyta) in the North Adriatic Sea (Mediterranean): molecular and morphological characterization

In this study we examined several specimens previously identified as C. clavulatum from the North Adriatic Sea (Italy and Croatia) using morphological and molecular methods to understand which species is effectively present in this area of the Mediterranean Sea. Centroceras spp. were collected along the Italian (33 samples) and Croatian (7 samples) coasts of the North Adriatic Sea from 10 different sampling sites (Fig. 1) during March 2018-October 2018. For each sample, part was silica gel-dried for molecular analyses, and part was preserved in 4% formaldehyde/ seawater solution for morphological observations. When necessary, material was stained with 0.5% aqueous toluidine blue. Specimens were observed using a light microscope (Optika B-510PH, OPTIKA, Italy) equipped with a digital image acquisition system. A voucher specimen was deposited at PAD Herbarium, Botanical Garden Padova (Italy)

Exploring the microbial diversity in Jordanian hot springs by comparative metagenomic analysis

A culture-independent approach was utilized in this study to reveal the microbial diversity in Jordanian hot springs represented by Ma\u27in and Afra hot springs. Water samples from Ma\u27in and Afra hot springs were collected in June 2015. The in situ temperature of water samples range was 38-59°C and the pH range was 7.4-8.4. The metagenome was extracted and analyzed using the next generation technology (bTEFAP ). A total of 314,310 sequences were parsed and 288,452 were then clustered. The sequences were predominated by bacteria (\u3e84%) and the relative abundance of archaea in each sample was \u3c1%. Eukaryotic microorganisms were detected but with varying abundances (0.6%-15%). Because most of the detected sequences were found to belong to the domain of bacteria (196,936 sequences out 288,452), the bacterial sequences were utilized for further microbial analyses. With respect to alpha and beta diversity, samples were rarefied to 30,000 sequences and bootstrapped at 10,000 sequences. The Shannon-Wiener Index curve plot reaches a plateau at approximately 3,000 sequences indicating that sequencing depth was sufficient to capture the full scope of microbial diversity. By examining the relative abundance of phyla detected in each sample, it appears that the biota of both Jordanian hot springs sampled are compositionally similar, with over 50% of the microbial community of each sample being comprised of the phylum Proteobacteria. The second most abundant phylum was the phylum Bacteroidetes which represents more than 13% in each sample. The phylum Firmicutes was also detected with a significant abundance. However, lower abundance of Deinococcus, Verrucomicrobia, Planctomycetes, and Chloroflexi was detected. A principal coordinate analysis plot was generated based upon the weighted UniFrac distance matrix. By utilizing Monte Carlo simulations, we were able to determine that there were no significant differences in the microbial diversity between each sample

Microbiological analysis, antimicrobial activity, and heavy-metals content of Jordanian Ma'in hot-springs water

Ma'in hot springs are known as sites of balneotherapy. However, little is known about their microbiology and chemistry. In this study, we aim at evaluating the antimicrobial activity of Ma'in hot-springs water (MHSW), studying its microbiology, and determining its physicochemical properties including the heavy metals content. Therefore, water samples were collected from Ma'in hot springs and tested for antimicrobial activity using agar diffusion method. Water was then cultivated on nutrient agar to isolate and identify the dominant bacteria by chemical and molecular methods. The identified strains were tested by cross streak method to evaluate their antimicrobial activity against different clinical and standard strains. Finally, water samples were chemically analyzed and the heavy-metals content was assessed. Results revealed that MHSW was not active against any of the clinical isolates. Nevertheless, MHSW was found to be active against five standard bacterial strains, namely, Staphylococcus epidermidis ATCC 12228 (inhibition zone: 20 mm), Staphylococcus aureus ATCC 29213 (inhibition zone: 19 mm), Micrococcus luteus ATCC 9341 (inhibition zone: 15.3 mm), and Bacillus cereus ATCC 11778 (inhibition zone: 12.3 mm). After cultivation of MHSW, five bacterial isolates were obtained and identified based on 16S rRNA gene analysis as new strains of Anoxybacillus flavithermus (identity percentage ranges between 96–99%). Physicochemical analysis revealed that the in situ temperature was 59 °C, pH was 7.8, salinity was 1.6 ppt, and dissolved oxygen was 3.8 mg l−1. In respect to heavy-metals content in MHSW, the following metals were present in the order: Cr (0.571 ppm) > Mn(0.169 ppm) > Fe (0.124 ppm) > Zn (0.095) > Cu(0.070 ppm) > Ni(0.058 ppm) > Cd (0.023 ppm) > Pb (0 ppm). Cd, Cr, Ni and Mn were found to be higher than permissible levels set by international organizations and countries. This study highlights new chemical and microbiological data about Ma'in hot springs. Keywords: Ma'in hot springs, Antimicrobial activity, Heavy metals, Water microbiology, Thermophilic bacteria, Balneotherap

Effect of Various Local Anthropogenic Impacts on the Diversity of Coral Mucus-Associated Bacterial Communities

The global continued decline in coral reefs is intensifying the need to understand the response of corals to local environmental stressors. Coral-associated bacterial communities have been suggested to have a swift response to environmental pollutants. This study aims to determine the variation in the bacterial communities associated with the mucus of two coral species, Pocillopora damicornis (Linnaeus, 1758) and Stylophora pistillata (Esper, 1792), and the coral-surrounding seawater from three areas exposed to contamination at the Jordanian coast of the Gulf of Aqaba (Red Sea), and also explores the antibacterial activity of these bacteria. Corals were collected from three contaminated zones along the coast, and the bacteria were quantified and identified by conventional morphological and biochemical tests, as well as 16S rRNA gene sequencing. The average number of bacteria significantly varied among the coral mucus from the sampling zones and between the coral mucus and the surrounding seawater. The P. damicornis mucus-associated bacterial community was dominated by members of the classes Gammaproteobacteria, Cytophagia, and Actinomycetia, while the mucus of S. pistillata represented higher bacterial diversity, with the dominance of the bacterial classes Gammaproteobacteria, Actinomycetia, Alphaproteobacteria, and Bacilli. The effects of local anthropogenic impacts on coral mucus bacterial communities were represented in the increased abundance of bacterial species related to coral diseases. Furthermore, the results demonstrated the existence of bacterial isolates with antibacterial activity that possibly acted as a first line of defense to protect and maintain the coral host against pathogens. Indeed, the dynamics of coral-associated microbial communities highlight the importance of holistic studies that focus on microbial interactions across the coral reef ecosystem