Recruitment preferences of blue mussel spat (Mytilus edulis) for different substrata and microhabitats in the White Sea

We tested the assumption that fouling pressure by the blue mussel Mytilus edulis on a small spatial scale - especially onto a given substratum type - is homogeneous. Artificial substrata were exposed to natural recruitment within and outside different microhabitats. These microhabitats were monospecific patches (diameter in the meter range) in a mixed subtidal community composed of the brown algae Laminaria saccharina, and Chorda tomentosa, the green filamentous alga Cladophora rupestris, and the blue mussel Mytilus edulis. While mussel spat settled in all microhabitats, recruitment was far from homogeneous. Within microhabitats, artificial substrata were preferred over living surfaces. Recruitment also differed between microhabitats exhibiting identical preference gradients on living surfaces and associated artificial substrata: recruitment preference for microhabitats increased in the order Laminaria saccharina < control area (stone or mud) < Chorda tomentosa < Cladophora rupestris < Mytilus edulis. In a second experimental approach on a smaller spatial scale (cm range), we assessed mussel recruitment in the vicinity of identical aliquots of some of the microhabitat-constituting species. Again, Laminaria proved to be of least, Cladophora of highest attractiveness. We conclude that primary settlement of mussel spat is not only influenced by the structure of the substratum (e.g. filamentous forms) but additionally by nearby macroorganisms - presumably by exuded chemical cues as suggested by the second experiment

Optical sensing of microbial life on surfaces

The label-free detection of microbial cells attached to a surface is an active field of research. The field is driven by the need to understand and control the growth of biofilms in a number of applications, including basic research in natural environments, industrial facilities, and clinical devices, to name a few. Despite significant progress in the ability to monitor the growth of biofilms and related living cells, the sensitivity and selectivity of such sensors are still a challenge. We believe that among the many different technologies available for monitoring biofilm growth, optical techniques are the most promising, as they afford direct imaging and offer high sensitivity and specificity. Furthermore, as each technique offers different insights into the biofilm growth mechanism, our analysis allows us to provide an overview of the biological processes at play. In addition, we use a set of key parameters to compare state-of-the-art techniques in the field, including a critical assessment of each method, to identify the most promising types of sensors. We highlight the challenges that need to be overcome to improve the characteristics of current biofilm sensor technologies and indicate where further developments are required. In addition, we provide guidelines for selecting a suitable sensor for detecting microbial cells on a surface

Living on the edge: Biofilms developing in oscillating environmental conditions

For the first time, the densities and diversity of microorganisms developed on ocean gliders were investigated using flow cytometry and Illumina MiSeq sequencing of 16S and 18S rRNA genes. Ocean gliders are autonomous buoyancy-driven underwater vehicles, equipped with sensors continuously recording physical, chemical, and biological parameters. Microbial biofilms were investigated on unprotected parts of the glider and surfaces coated with base, biocidal and chitosan paints. Biofilms on the glider were exposed to periodical oscillations of salinity, oxygen, temperature, pressure, depth and light, due to periodic ascending and descending of the vehicle. Among the unprotected surfaces, the highest microbial abundance was observed on the bottom of the glider’s body, while the lowest density was recorded on the glider’s nose. Antifouling paints had the lowest densities of microorganisms. Multidimensional analysis showed that the microbial communities formed on unprotected parts of the glider were significantly different from those on biocidal paint and in seawater

Studies of concentration and temperature dependencies of precipitation kinetics in iron-copper alloys using kinetic monte carlo and stochastic statistical simulations

The earlier-developed ab initio model and the kinetic Monte Carlo method (KMCM) are used to simulate precipitation in a number of iron-copper alloys with different copper concentrations x and temperatures T. The same simulations are also made using the improved version of the earlier-suggested stochastic statistical method (SSM). The results obtained enable us to make a number of general conclusions about the dependencies of the decomposition kinetics in Fe-Cu alloys on x and T. We also show that the SSM describes the precipitation kinetics in a fair agreement with the KMCM, and employing the SSM in conjunction with the KMCM enables us to extend the KMC simulations to the longer evolution times. The results of simulations seem to agree with available experimental data for Fe-Cu alloys within statistical errors of simulations and the scatter of experimental results. Comparison of results of simulations to experiments for some multicomponent Fe-Cu-based alloys enables us to make certain conclusions about the influence of alloying elements in these alloys on the precipitation kinetics at different stages of evolution.Comment: 18 pages, 17 postscript figures, LaTe

Gramella portivictoriae sp nov, a novel member of the family Flavobacteriaceae isolated from marine sediment (vol 55, pg 2497, 2005)

A yellow-pigmented, Gram-negative, slowly gliding, rod-shaped, strictly aerobic bacterium (UST040801-001T) was isolated from marine sediment. The DNA G+C content was 39?9 mol%. The predominant fatty acids were a15 : 0, i15 : 0, i15 : 0 3-OH, i17 : 1v9c, i17 : 0 3-OH and summed feature 3, comprising i15 : 0 2-OH and/or 16 : 1v7c (altogether representing 76?2% of the total). MK-6 was the only respiratory quinone. Flexirubin-type pigments were not produced. Phylogenetic analysis based on 16S rRNA gene sequences indicated that Gramella echinicola KMM 6050T (the only species in the genus) was the closest relative of UST040801-001T, sharing 98?0% sequence similarity. The DNA–DNA relatedness between UST040801-001T and Gramella echinicola KMM 6050T was 13 %. Strain UST040801-001T can be distinguished from G. echinicola by means of 11 phenotypic traits. The results of molecular and phenotypic analyses suggested that UST040801-001T represents a novel species of Gramella. The name Gramella portivictoriae sp. nov. is proposed for this bacterium, with UST040801-001T (=NRRL 41137T=JCM 13192T) as the type strain

Bioactive Compounds from Omani Soft Corals Belonging to Genera Sarcophyton and Sinularia

Soft corals are marine invertebrates belonging to the class Anthozoa and are rich in bioactive substances that provide their defense and protection from predators, pathogens, and other unfavorable organisms. Seven soft coral species belonging to the genera Sarcophyton and Sinularia were collected from Omani water and extracted and their antibacterial and antifungal properties were tested using the agar-disk diffusion method and a MicroResp technique. Potential compounds that were present in the species were characterized using GC-MS analysis. The results showed that the soft coral species have anti-bacterial activity against Gram-negative bacteria Pseudomonas putida and Pseudomonas tunicata. The GC-MS analysis found the presence of antibacterial, antifungal, antiviral, anticancer, antioxidant agents, agrochemicals, and medicine chemicals. Three novel compounds were found in a Sarcophyton sp. In addition, the compound Andrographolide found in a Sarcophyton sp. has been recently studied as an antiviral agent against SAR-CoV-2. Moreover, the compound Decosane which is found in Sinularia sp. has been used as an anti-parasitic agent against the female Anopheles mosquito to treat malaria in Pakistan. This study highlighted the importance of Omani soft corals as a source of novel bioactive compounds

Stenothermobacter spongiae gen. nov., sp. nov., a novel member of the family Flavobacteriaceae isolated from a marine sponge in the Bahamas, and emended description of Nonlabens tegetincola

A bacterial strain, UST030701-156T, was isolated from a marine sponge in the Bahamas. Strain UST030701-156T was orange-pigmented, Gram-negative, rod-shaped with tapered ends, slowly motile by gliding and strictly aerobic. The predominant fatty acids were a15 : 0, i15 : 0, i15 : 0 3-OH, i17 : 0 3-OH, i17 : 1ω9c and summed feature 3, comprising i15 : 0 2-OH and/or 16 : 1ω7c. MK-6 was the only respiratory quinone. Flexirubin-type pigments were not produced. Phylogenetic analysis based on 16S rRNA gene sequences placed UST030701-156T within a distinct lineage in the family Flavobacteriaceae, with 93·3 % sequence similarity to the nearest neighbour, Nonlabens tegetincola. The DNA G+C content of UST030701-156T was 41·0 mol% and was much higher than that of N. tegetincola (33·6 mol%). Strain UST030701-156T can be distinguished from other members of the Flavobacteriaceae by means of a number of chemotaxonomic and phenotypic characteristics. It is proposed, therefore, that UST030701-156T represents a novel taxon designated Stenothermobacter spongiae gen. nov., sp. nov. The type strain is UST030701-156T (=NRRL B-41138T=JCM 13191T). Carbon-source utilization by N. tegetincola was re-examined and an emended description is therefore included

Description of Fabibacter halotolerans gen. nov., and reclassification of [Marinicola] seohaensis as Roseivirga seahaensis comb. nov.

Bacterial strains UST030701-097T and UST030701-084T were isolated from a marine sponge in the Bahamas. Both strains were pink-pigmented, Gram-negative, strictly aerobic and chemo-organotrophic. Cells of strain UST030701-097T were short, curved rods with fast-gliding motility, whereas those of strain UST030701-084T were straight rods with a less rapid gliding motion. The two strains had MK-7 as the major respiratory quinone and did not produce flexirubin-type pigments. The DNA G+C contents of strains UST030701-097T and UST030701-084T were 42.5 and 43.7 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the two strains belonged to the family 'Flexibacteraceae' of the phylum Bacteroidetes. 16S rRNA gene sequence similarity between strains UST030701-097T and UST030701-084T was 95.0 %; their closest relative was [Marinicola] seohaensis, with 93.3 % and 96.0 % sequence similarity, respectively. Phylogenetic tree topology indicated that the two strains belonged to the same lineage, but were on separate branches. Whilst strain UST030701-084T and [Marinicola] seohaensis were found on one branch, strain UST030701-097T was in another branch that had no species with validly published names. Based on the polyphasic taxonomic data obtained in the present study, we propose that strain UST030701-097T represents a novel genus and that strain UST030701-084T represents a novel species in the phylum Bacteroidetes. The genus Fabibacter gen. nov. is proposed, with strain UST030701-097T (=NRRL B-41220T=JCM 13334T) as the type strain of the type species, Fabibacter halotolerans sp. nov. Strain UST030701-084T (=NRRL B-41219T=JCM 13337T) is proposed as the type strain of Roseivirga spongicola sp. nov. In an earlier study, it was suggested that the genus Marinicola is a later heterotypic synonym of the genus Roseivirga. However, a formal proposal to reclassify [Marinicola] seohaensis, the only member of the genus Marinicola, has not yet been made. The results of phylogenetic analyses in this study support the reclassification of [Marinicola] seohaensis as Roseivirga seohaensis comb. nov

Relevance of mytilid shell microtopographies for fouling defence - a global comparison

Prevention of epibiosis is of vital importance for most aquatic organisms, which can have consequences for their ability to invade new areas. Surface microtopography of the shell periostracum has been shown to have antifouling properties for mytilid mussels, and the topography shows regional differences. This article examines whether an optimal shell design exists and evaluates the degree to which shell microstructure is matched with the properties of the local fouling community. Biomimics of four mytilid species from different regional provenances were exposed at eight different sites in both northern and southern hemispheres. Tendencies of the microtopography to both inhibit and facilitate fouling were detected after 3 and 6 weeks of immersion. However, on a global scale, all microtopographies failed to prevent fouling in a consistent manner when exposed to various fouling communities and when decoupled from other shell properties. It is therefore suggested that the recently discovered chemical anti-microfouling properties of the periostracum complement the anti-macrofouling defence offered by shell microtopography