Konstantinos Kormas

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Verified

Konstantinos verified their affiliation via an institutional email.

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• B.Sc., Ph.D.
• Professor (Full) at University of Thessaly

The rapidly developing field of targeted analysis of metagenomes focuses on retrieving information about specific genes and/or genome(s) from environmental DNA. The traditional shotgun sequencing methods overemphasise dominant microorganisms and often fail to confidently assign the entirety of the analysed genetic material to specific species, geno...

This study evaluated the dietary fishmeal substitution by full-fat (FF) and defatted (DF) Zophobas morio meals regarding growth, feed efficiency, proximate and fatty acid compositions, digestive enzymes activities, histology and midgut microbiota in gilthead seabream (Sparus aurata). Juveniles initially weighing 3.4 g were distributed to triplicate...

The persistence and specificity of fish host-microbial interaction during evolution is an important part of exploring the host-microbial symbiosis mechanism. However, it remains unclear how the environmental and host factors shape fish host-microbe symbiotic relationships in subtropical rivers with complex natural environments. Freshwater fish are...

Despite the ecological and economic interest of the Norway lobster ( Nephrops norvegicus ), its gut microbiota remains largely understudied. The current study aimed at investigating the gut bacterial microbiota in three geographically separated N. norvegicus populations from the Mediterranean and the North Sea and detect any potential sex-related m...

Understanding niche dimensions and interspecific niche overlap is fundamental for evaluating resource partitioning and competitive interactions among sympatric species. Microbial symbiont acquisition facilitates rapid adaptation to novel ecological niches, substantially augmenting host evolutionary fitness and ecological success. Nevertheless, the...

The introduction of the holobiont concept has triggered scientific interest in depicting the structural and functional diversity of animal microbial symbionts, which has resulted in an unprecedented wealth of such cross-domain biological associations. The steadfast technological progress in nucleic acid-based approaches would cause one to expect th...

The persistence and specificity of fish host-microbial interaction during evolution is an important part of exploring the host-microbial symbiosis mechanism. However, it remains unclear how the environmental and host factors shape fish host-microbe symbiotic relationship in subtropical rivers with complex natural environments. Freshwater fish are i...

Elucidating marine microbiota diversity and dynamics holds significant importance due to their role in maintaining vital ecosystem functions and services including climate regulation. This work aims to contribute in the understanding of microbial ecology and networking in one of the world’s most understudied marine regions, the Eastern Mediterranea...

Telonemia are one of the oldest identified marine protists that for most part of their history have been recognized as a distinct incertae sedis lineage. Today, their evolutionary proximity to the SAR supergroup (Stramenopiles, Alveolates, and Rhizaria) is firmly established. However, their ecological distribution and importance as a natural predat...

Turbulence is one of the least investigated environmental factors impacting the ecophysiology of phytoplankton, both at the community and individual species level. Here, we investigated, for the first time, the effect of a turbulence gradient (Reynolds number, from Reλ = 0 to Reλ = 360) on two species of the marine diatom Pseudo-nitzschia and their...

Coastal ecosystems typically comprise water patches of different salinities that host distinct communities of species. This salinity-driven heterogeneity can be vulnerable to changes in between-patch connectivity due to altered water levels. Despite the potentially grave implications for higher trophic levels, the impact of increased connectivity o...

The gills and skin microbiota and microbiome of wild fish remain far more under-investigated compared to that of farmed fish species, despite that these animal-microbe interactions hold the same ecophysiological roles in both cases. In this study, the gills and skin bacterial microbiota profiles and their presumptive bacterial metabolisms were inve...

Understanding the diversity and dynamics of marine microbiota holds significant importance due to their role in maintaining vital ecosystem functions and services including climate regulation and bioremediation. Here, we studied the diversity and associations between Bacteria and unicellular eukaryotes in the different water masses of the Cretan Pa...

As aquaculture is nowadays the major fish-food production sector, continuous research is undergoing for aquafeeds that could replace conventional fishmeal in order to enhance its environmental and economic sustainability. Fish gut microorganisms might be involved in nutrient assimilation and thus they are crucial for their hosts’ well-being. In thi...

The gills and skin microbiota and microbiome of wild fish remain far more under-investigated compared to that of farmed fish species, despite that these animal-microbe interactions hold the same ecophysiological roles in both cases. In this study, the gills and skin bacterial microbiota profiles and their presumptive bacterial metabolisms were inve...

The aim of this work was to evaluate the effects of dietary microalgae blends as fish oil replacers οn the midgut bacterial microbiota of gilthead sea bream (Sparus aurata). The control diet (FO) contained only fish oil as source of lipids, EPA and DHA fatty acids, while three experimental diets were used where fish oil was replaced at 67% by one o...

Background-Aim Protistan communities have a major contribution to biochemical processes and food webs in coastal ecosystems. However, related studies are scarce and usually limited in specific groups and/or sites. The present study examined the spatial structure of the entire protistan community in seven different gulfs and three different depths i...

The role of animal host-associated microbiomes is becoming more apparent and defined for wild animals, especially for the species under conservation strategies. This study investigated the succession of fecal and skin bacterial microbiota of two rescued female Mediterranean monk seal ( Monachus monachus ) pups for most of their rehabilitation perio...

The use of antibiotics in open-water aquaculture is often unavoidable when faced with pathogens with high mortality rates. In addition, seasonal pathogen surges have become more common and more intense over the years. Apart from the apparent cost of antibiotic treatment, it has been observed that, in aquaculture practice, the surviving fish often d...

The role of animal host-associated microbiomes is becoming more apparent and defined for wild animals, especially for the species under conservation strategies. This study investigated the succession of fecal and skin bacterial microbiota of two rescued female Mediterranean monk seal (Monachus monachus) pups for most of their rehabilitation period....

Simple Summary Optimization of metamorphosis, a key stage in development where fish undergo several morphological and physiological changes, may assure the efficient mass production of greater amberjack (Seriola dumerili) juveniles. Application of probiotics as feed and/or water additive benefits nutrient utilization through modulation of the diges...

Cyanobacterial biomass such as spirulina (Arthrospira spp.) is widely available as a food supplement and can also be added to foods as a nutritionally beneficial ingredient. Spirulina is often produced in open ponds, which are vulnerable to contamination by various microorganisms, including some toxin-producing cyanobacteria. This study examined th...

The possibility of simultaneous production of halophyte and euryhaline fish creates huge interest in both commercial aquaponics systems and in research. The aim of the present study was to investigate the effect of three different salinities (8, 14, and 20 ppt) on the growth performance and survival rate of sea bream (Sparus aurata) and rock samphi...

Brackish aquaponics using euryhaline fish and halophyte plants may be a sustainable method of functional food production. In addition, they could have a great potential as high nutritional, commercial and pharmaceutical value. This study investigated the effect of three different salinity levels (8 ppt, 14 ppt and 20 ppt) on the growth performance...

Fish microbiome science is progressing fast, but it is biased toward farmed or laboratory fish species against natural fish populations, which remain considerably underinvestigated. We analyzed the midgut bacterial microbiota of 45 specimens of 12 fish species collected from the Gyaros Island marine protected area (Aegean Sea, Greece). The species...

Cell growth and differentiation signals of insulin-like growth factor-1 (IGF-1), a key regulator in embryonic and postnatal development, are mediated through the IGF-1 receptor (IGF-1R), which activates several downstream pathways. The present study aims to address crucial organogenesis and development pathways including Akt, MAPKs, heat shock resp...

Remote sensing of inland waters is challenging, but also important, due to the need to monitor the ever-increasing harmful algal blooms (HABs), which have serious effects on water quality. The Ocean and Land Color Instrument (OLCI) of the Sentinel-3 satellites program is capable of providing images for the monitoring of such waters. Atmospheric cor...

In aquaponics, a closed-loop system which combines fish and crop production, essential nutrients for plant growth are often at sub-optimal concentrations. The aim of the present study was to identify system limitations and thoroughly examine the integrated response of its components to minimal external inputs, notably crop’s functional parameters,...

Understanding the processes that underlay an ecological disaster represents a major scientific challenge. Here, we investigated phytoplankton and zooplankton community changes before and during a fauna mass kill in a European protected wetland. Evidence on gradual development and collapse of harmful phytoplankton blooms, allowed us to delineate the...

Fish microbiome science is progressing fast, but it is biased toward farmed or labora-tory fish species against natural fish populations, which remain considerably underinvestigated. We analysed the midgut bacterial microbiota of 45 specimens of 12 fish species collected from the Gyaros Island marine protected area (Aegean Sea, Greece). The species...

Intensive aquaculture food production has been continually increasing over the past decades. Recirculating aquaculture is an innovative technology which relies on water reuse and removal of toxic metabolites by utilizing specific prokaryotic groups such as nitrifiers, settled in special biofilters. Focused on recent next generation sequencing‐based...

The Aegean Sea is a highly oligotrophic marine region and as such the microbial food web is of particular interest for its functioning, especially under conditions of climate change. Structural and functional microbial diversity are the key components to elucidate which microorganisms mediate specific metabolic pathways in certain seasons and depth...

Herein, the effect of dietary inclusion of insect ( Tenebrio molitor ) meal on hepatic pathways of apoptosis and autophagy in three farmed fish species, gilthead seabream ( Sparus aurata ), European seabass ( Dicentrarchus labrax ) and rainbow trout ( Oncorhynchus mykiss ), fed diets at 25%, 50% and 60% insect meal inclusion levels respectively, wa...

Cyanobacterial blooms have been known since ancient times; however, they are currently increasing globally. Human and ecological health risks posed by harmful cyanobacterial blooms have been recorded around the world. These risks are mainly associated with their ability to affect the ecosystem chain by different mechanisms like the production of cy...

Featured Application Poultry by-product meal and hydrolyzed feather meal can successfully replace fishmeal at low dietary levels in feeds for farmed gilthead seabream and thus enhance the environmental and economic sustainability of its production. Abstract The effects on liver and intestinal histomorphology and on intestinal microbiota in gilthea...

Like for other vertebrates, the fish microbiome is critical to the health of its host and has complex and dynamic interactions with the surrounding environment. Thus, the study of the fish microbiome can benefit from the new prospects gained by innovative biotechnological applications in human and other animals, that include manipulation of the ass...

The aim of this study is to investigate the effect of three daily fish feeding frequencies, two, four and eight times per day (FF2, FF4, and FF8, respectively) on growth performance of sea bass ( Dicentrarchus labrax )and lettuce plants ( Lactuca sativa ) reared in aquaponics. 171 juvenile sea bass with an average body weight of 6.80 ± 0.095 g were...

Decline in fish oil and fish meal availability has forced the aquaculture sector to investigate alternative and sustainable aquafeed ingredients. Despite that several studies have evaluated the effect of fish oil replacement in aquaculture fish species, there is a knowledge gap on the effects of alternative dietary lipid sources on the gut microbio...

Arthrospira (“Spirulina”) is the most used cyanobacterium in food supplementation. “Spirulina” products are considered as superfood due to their excellent nutritional content, although several studies have shown the toxic effects of short and long term “Spirulina” consumption. In this work, a total of 31 “Spirulina” products from different brands,...

Irrigation water coming from freshwater bodies that suffer toxic cyanobacterial blooms causes adverse effects on crop productivity and quality and raises concerns regarding food contamination and human exposure to toxins. The common agricultural practice of spray irrigation is an important exposure route to cyanotoxins, yet its impact on crops has...

The diversity and degradation capacity of hydrocarbon-degrading consortia from surface and deep waters of the Eastern Mediterranean Sea were studied in time-series experiments. Microcosms were set up in ONR7a medium at in situ temperatures of 25 °C and 14 °C for the Surface and Deep consortia, respectively, and crude oil as the sole source of carbo...

Insect meals are considered promising, eco-friendly, alternative ingredients for aquafeed. Considering the dietary influence on establishment of functioning gut microbiota, the effect of the insect meal diets on the microbial ecology should be addressed. The present study assessed diet- and species-specific shifts in gut resident bacterial communit...

In this study, we hypothesized that sympatrically grown farmed fish, i.e. fish which experience similar environmental conditions and nutritionally similar diets, would have more convergent gut microbiota. Using a “common garden” approach, we identified the core microbiota and bacterial community structure differences between five fish species farme...

Geothermal springs are essentially un‐affected by environmental conditions aboveground as they are continuously supplied with subsurface water with little variability in chemistry. Therefore, changes in their microbial community composition and function, especially over a long period, are expected to be limited but this assumption has not yet been...

Backgound: The present study investigated the effect of different lipid source in the feed on the colonization and the bacterial succession in early life stages (fertilized eggs until 93 days post first feeding) of S. salar. The two diets used in this study, FD (fish oil based diet) and VD (vegetable oil based diet), were formulated to cover the fi...

Backgound: The present study investigated the effect of different lipid source in the feed on the colonization and the bacterial succession in early life stages (fertilized eggs until 93 days post first feeding) of S. salar. The two diets used in this study, FD (fish oil based diet) and VD (vegetable oil based diet), were formulated to cover the fi...

Backgound: The present study investigated the effect of different lipid source in the feed on the colonization and the bacterial succession in early life stages (fertilized eggs until 93 days post first feeding) of S. salar. The two diets used in this study, FD (fish oil based diet) and VD (vegetable oil based diet), were formulated to cover the fi...

Cyanobacterial blooms have become a frequent phenomenon in freshwaters worldwide; they are a widely known indicator of eutrophication and water quality deterioration. Information and knowledge contributing towards the evaluation of the ecological status of freshwaters, particularly since many are used for recreation, drinking water, and aquaculture...

In Skiathos Island the water is not potable due to mercury contamination and salinization. The mercury’s origin is natural due to the existence of cinnabar in the Skiathos aquifer as a mineral in the Earth’s crust. The possibility of mercury contaminants ending up in the coastal area was investigated through a field experiment. Mussels (Mytilus gal...

Recent discoveries suggest that the candidate superphyla Patescibacteria and DPANN constitute a large fraction of the phylogenetic diversity of Bacteria and Archaea. Their small genomes and limited coding potential have been hypothesized to be ancestral adaptations to obligate symbiotic lifestyles. To test this hypothesis, we performed cell–cell as...

Despite the technical progress in high-throughput sequencing technologies, defining the sample size which is capable of yielding representative inferences in metabarcoding analysis still remains debatable. The present study addresses the influence of individual variability in assessing dietary effects on fish gut microbiota parameters and estimates...

Geothermal springs are barely affected by environmental conditions aboveground as they are continuously supplied with subsurface water with little variability in chemistry. Therefore, changes in their microbial community composition and function, especially over a long period, are expected to be limited but this assumption has not yet been rigorous...

Microcystins (MCs) are toxins produced during cyanobacterial blooms. They reach soil and translocated to plants through irrigation of agricultural land with water from MC-impacted freshwater systems. To date we have good understanding of MC effects on plants, but not for their effects on plant-associated microbiota. We tested the hypothesis that MC...

Recent discoveries suggest that the candidate superphyla Patescibacteria and DPANN constitute a large fraction of the phylogenetic diversity of Bacteria and Archaea. Their small genomes and limited coding potential have been hypothesized to be ancestral adaptations to obligate symbiotic lifestyles. To test this hypothesis, we performed cell-cell as...

Mud volcanoes and pockmarks are sites which methane and other gases seep out towards the overlying water. This supply and the microbiologically-mediated processes of these cold seeps can be the basis of unique microbial habitats. Although mud volcanoes and pockmarks vary in the seepage rate and chemical composition of their outflows, the communitie...

The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions against reference (or nonimpaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise. Another important...

Unicellular eukaryotes have pivotal ecological roles in aquatic ecosystems by participating in biogeochemical processes and structuring microbial food webs. However, revealing their biogeographical patterns remains challenging, as it is reflected in the rather limited available knowledge. In this study, two central patterns, the taxa–area and the d...

The idea that 'everything is everywhere, but the environment selects' has been seminal in microbial biogeography, and marine phytoplankton is one of the prototypical groups used to illustrate this. The typical argument has been that phytoplankton is ubiquitous, but that distinct assemblages form under environmental selection. It is well established...

Bacterial and archaeal diversity and succession were studied during a mesocosm experiment that investigated whether changing light regimes could affect the onset of phytoplankton blooms. For this, 454-pyrosequencing of the bacterial V1–V3 and archaeal V3–V9 16S rRNA regions was performed in samples collected from four mesocosms receiving different...

Since the introduction of the term holobiont [...]

Brackish aquaponics using Mediterranean fish and plants provides an alternative opportunity for a combined production of high-quality food products with high commercial and nutritional value. This is the first study that investigates the effect of two different salinities (8 and 20 ppt) on growth and survival of Sparus aurata and Crithmum maritimum...

One of the most widely reared fish in the Mediterranean Sea is Sparus aurata. The succession of S. aurata whole-body microbiota in fertilized eggs, five, 15, 21 and 71 days post hatch (dph) larvae and the contribution of the rearing water and the provided feed (rotifers, Artemia sp. and commercial diet) to the host’s microbiota was investigated by...

Aquaponics combines the culture of aquatic animals and the cultivation of plants in recirculating systems, integrating aquaculture and hydroponics in a soil-less system. The present study aims to evaluate the relationship between water quality parameters and fish and plant growth in an aquaponics system. Two aquaponics systems, 720L total water cap...

The overall objective of FutureEUAqua is to effectively promote sustainable growth of resilient to climate changes, environmentally friendly organic and conventional aquaculture of major fish species and low trophic level organisms in Europe, to meet future challenges with respect to the growing consumer demand for high quality, nutritious and resp...

The aquaculture industry is currently looking for alternative, sustainable diets that provide similar or better growth for the reared species. We investigated whether replacing fishmeal with yellow mealworm (Tenebrio molitor) meal in the supplied diets of the gilthead sea bream (Sparus aurata), European sea bass (Dicentrarchus labrax) and rainbow t...

Recent diversity studies have revealed that microbial communities of natural environments are dominated by species-like, sequence-discrete populations. However, how stable the sequence and gene-content diversity are within these populations and especially in highly dynamic lotic habitats remain unclear. Here we quantified the dynamics of intra-popu...

Cyanotoxin-rich irrigation water was applied by spraying and root irrigation on spinach (Spinacia oleracea L.) and the effect on growth and toxin loading in the edible tissues, subsequently health risk, was investigated. The degraded water was collected from the Karla Lake, Central Greece, which is characterised by eutrophic conditions and increase...

This study investigated the profile of the autochthonous gut bacterial communities in adult individuals of Sparus aurata and Dicentrarchus labrax reared in sea cages in five distantly located aquaculture farms in Greece and determine the impact of geographic location on them in order to detect the core gut microbiota of these commercially important...

The enactment of the Water Framework Directive (WFD) initiated scientific efforts to develop reliable methods for comparing prevailing lake conditions against reference (or non- impaired) states, using the state of a set biological elements. Drawing a distinction between impaired and natural conditions can be a challenging exercise, as it stipulate...

Chitinolytic bacteria are widespread in marine and terrestrial environment, and this is rather a reflection of their principle growth substrate’s ubiquity, chitin, in our planet. In this paper, we investigated the development of naturally occurring bacterial biofilms on the exoskeleton of the shrimp Melicertus kerathurus during its degradation in s...

This study investigated the impact of different dietary ingredients with different protein/lipid sources on the midgut and feaces bacteria communities structure just before feeding and 3h after feeding a single meal on rainbow trout (Oncorhynchus mykiss) individuals. Fish were kept in experimental rearing facilities and fed ad libitum two times dai...

The Black Sea harbors unique microbiotas shaped by its specific hydrographic and hydro-chemical conditions. However the observational data on specific pathogenic bacteria is scarce. The monitoring programs in the Black Sea are mostly designed to determine the level of faecal bacteriological indicators in the recreational waters based on cultivation...

Toxic cyanobacterial blooms have been implicated for their negative consequences on many terrestrial and aquatic organisms. Water birds belong to the most common members of the freshwater food chains and are most likely to be affected by the consumption of toxic cyanobacteria as food. However, the contribution of cyanotoxins in bird mortalities is...

This study investigated the microcystins (MCs)-rich irrigation water effect on lettuce of different developmental stages, i.e. during a two months period, covering the whole period from seed germination to harvest at marketable size of the plant. We followed four lettuce plant groups receiving MCs-rich water (1.81 μg l⁻¹ of dissolved MCs), originat...

This paper presents the establishment and the first outcomes of the Hellenic Ecosystem Services Partnership (HESP), a scientific-technical committee aiming at the guidance and coordination of the Ecosystem Services (ES) assessment in Greece. HESP consists of experts from different disciplines (ecology, marine biology, socio-ecological system scienc...

In this chapter details of sampling and sample storage for DNA and RNA analysis are described. Since the sampling strategy and storage protocol are of decisive importance for subsequent analysis, downstream analysis using molecular tools should be defined before the sampling step. This chapter includes protocols to sample planktonic (SOP 2.1) and b...

Microbes are considered to have a global distribution due to their high dispersal capabilities. However, our knowledge of the way geographically distant microbial communities assemble after dispersal in a new environment is limited. In this study, we examined whether communities would converge because similar taxa would be selected under the same e...