Influence of cyclonic and anti-cyclonic eddies on plankton biomass, activity and diversity in the southeastern Mediterranean Sea

Planktonic food-webs were studied contemporaneously in a mesoscale cyclonic (upwelling, ~13 months old) and an anti-cyclonic (down-welling, ~2 months old) eddies, as well as in an uninfluenced-background situation in the oligotrophic southeastern Mediterranean Sea (SEMS) during late summer 2018. We show that integrated nutrients concentrations were higher at the cyclone compared to the anti-cyclone or the background stations by 2–13 fold. Concurrently, Synechococcus and Prochlorococcus were the dominant community component abundance-wise in the oligotrophic anti-cyclone (~300 × 1010 cells m−2). In the cyclone, pico- and nanoeukaryotes such as dinoflagellates, Prymnesiophyceae and Ochrophyta contributed substantially to the total phytoplankton abundnce (~14 × 1010 cells m−2) which was ~65 % lower in the anti-cyclone/background stations (~5 × 1010 cells m−2). Primary production was highest in the cyclonic eddy (191 mg C m−2 d−1) and was 2–5 fold lower outside the eddy area. The calculated doubling time of phytoplankton was ~3 days in the cyclone and ~5–10 days at the anti-cyclone/background stations, further reflecting the nutritional differences between these environments. Heterotrophic prokaryotic cell-specific activity was highest in the cyclone (~10 fg C cell−1 d−1), while the least productive cells were found in the anti-cyclone (4 fg C cell−1 d−1). The calculated doubling time of heterotrophic bacteria were 1.4 days in the cyclone and 2.5–3.5 days at the anti-cyclone/background stations. Total zooplankton biomass in the upper 300 m was tenfold higher in the cyclone compared with the anti-cyclone or background stations (1337 vs. 112–133 mg C m−2, respectively). Copepod diversity was much higher in the cyclone (44 species), compared to the anti-cyclone (6 small-size species). Our results highlight that cyclonic and anti-cyclonic eddies show significantly different community compositions and food-web dynamics in oligotrophic environments, with cyclones representing productive oases in the marine desert of the SEMS.

Biofloc Systems for Sustainable Production of Economically Important Aquatic Species: A Review

The increasing global population has led to an increase in food demand; consequently, aquaculture is one of the food production sectors that has offered opportunities to alleviate hunger, malnutrition, and poverty. However, the development of a sustainable aquaculture industry has been hindered by the limited availability of natural resources as well as its negative impact on the surrounding environment. Hence, there is an urgent need to search for better aquacultural production systems that, despite their high productivity and profitability, utilize fewer resources such as water, energy, land, and capital in conjunction with a negligible impact on the environment. Biofloc technology (BFT) is one of the most exciting and promising sustainable aquaculture systems; it takes into account the intensive culture of aquatic species, zero water exchange, and improved water quality as a result of beneficial microbial biomass activity, which, at the same time, can be utilized as a nutritious aquaculture feed, thus lowering the costs of production. Furthermore, BFT permits the installation of integrated multi-trophic aquaculture (IMTA) systems in which the wastes of one organism are utilized as feed by another organism, without a detrimental effect on co-cultured species. This review, therefore, highlights the basics of BFT, factors associated with BFT for the successful production of aquatic species, the significance of this food production system for the sustainable production of economically important aquatic species, its economic aspects, drawbacks, limitations, and recommended management aspects for sustainable aquaculture.

Biomass of a Psychrophilic Fungus as a Biocatalyst for Efficient Direct Esterification of Citronellol

A biomass-bound lipase from psychrophilic Chrysosporium pannorum A-1 is an efficient biocatalyst for direct esterification of β-citronellol and acetic acid in an organic solvent. The biomass is effectively produced by fungal submerged culture at 20 ℃, which results in lower energy consumption during the production of biocatalyst. Supplementation of the culture medium with calcium carbonate together with olive oil contributed to a significant increase in the active biomass of mycelium in one batch culture and increased the efficiency of the biocatalyst. Biomass-bound lipase showed high catalytic activity in a broad temperature range of 30–60 °C and stability up to 70 °C. A maximum molar conversion value of 98% was obtained at 30 °C in n-hexane using a 2:1 alcohol-to-acid molar ratio and 3% w/v of the biocatalyst within 24 h. The high equimolar concentration of the substrates (200 mM) did not have an adverse effect on mycelial biomass activity. Dry mycelium of C. pannorum is a promising biocatalyst for large-scale biosynthesis of citronellyl acetate, given its low-cost production, high activity at low temperatures, and reusability in a minimum of seven 24-h biocatalytic cycles.

A Review on the Properties of Biomass Active Mixed Materials for Concrete

Experiment shows that wheat straw ash has rich biomass activity. Many scholars have shown that the strength, durability, freezing and thawing resistance of concrete have changed greatly after the wheat straw ash material is mixed into concrete as an active mixed material. This paper reviews and looks forward to the future development direction.

Nitrate-Enrichment Structures Phytoplankton Communities in the Shallow Eastern Mediterranean Coastal Waters

Submarine groundwater discharge (SGD) has been shown to be an important source of nutrients in coastal environments, especially nitrogen and silica, and thereby relive nutrient limitation to phytoplankton. Here, we followed autotrophic microbial biomass, activity, and community composition at a site strongly influenced by SGD and a nearby nutrients-poor reference site at the oligotrophic Israeli shallow rocky coast [southeastern Mediterranean Sea (SEMS)] between 2011 and 2019. The surface water at the SGD-affected area had significantly higher NO3 + NO2 (∼10-fold) and Si(OH)4 (∼2-fold) levels compared to the reference site, while no significant differences were observed for PO4 or NH4. This resulted in a significant increase in algae biomass (∼3.5-fold), which was attributed to elevated Synechococcus (∼3.5-fold) and picoeukaryotes (∼2-fold) at the SGD-affected site, and in elevated primary production rates (∼2.5-fold). Contrary to most SGD-affected coastal areas, diatoms biomass remained unchanged between sites, despite the elevated N and Si, suggesting the dominance of picophytoplankton over microphytoplankton at the SEMS. DNA sequencing of the 16S and 18S rDNA supported these findings. These results highlight the influence of SGD on shallow-water microbial populations. Our observations are consistent with recent studies showing that phytoplankton along the Israeli coast are likely nitrogen + silica limited, and may have important ecological and regulatory implications for environmental policy and management of coastal aquifers.

Development of Decay in Biofilms under Starvation Conditions—Rethinking of the Biomass Model

The study investigates the decay of heterotrophic biomass in biofilms under starvation conditions based on measurements of the oxygen uptake rate (OUR). Original incentive was to understand the preservation of active biomass in SBR-trickling filter systems (SBR-TFS), treating event-based occurring, organically polluted stormwater. In comparison with activated sludge systems, the analyzed biofilm carrier of SBR trickling filters showed an astonishing low decay rate of 0.025 d−1, that allows the biocenosis to withstand long periods of starvation. In activated sludge modeling, biomass decay is regarded as first order kinetics with a 10 times higher constant decay rate (0.17–0.24 d−1, depending on the model used). In lab-scale OUR measurements, the degradation of biofilm layers led to wavy sequence of biomass activity. After long starvation, the initial decay rate (comparable to activated sludge model (ASM) approaches) dropped by a factor of 10. This much lower decay rate is supported by experiments comparing the maximum OUR in pilot-scale biofilm systems before and after longer starvation periods. These findings require rethinking of the approach of single-stage decay rate approach usually used in conventional activated sludge modelling, at least for the investigated conditions: the actual decay rate is apparently much lower than assumed, but is overshadowed by degradation of either cell-internal substrate and/or the ability to tap “ultra-slow” degradable chemical oxygen demand (COD) fractions. For the intended stormwater treatment, this allows the application of technical biofilm systems, even for long term dynamics of wastewater generation.

In vitro interaction of hormone-conditioned neutrophils with commensal and uropathogenic Escherichia coli biofilms

The aim of the work was to examine an interaction between neutrophils conditioned with chorionic gonadotropin, estriol, kisspeptin, leptin, ghrelin and commensal and uropathogenic Escherichia coli biofilms. Peripheral blood neutrophils isolated from healthy non-pregnant women in the first phase of the menstrual cycle (n = 8) were cultured in vitro for 1 hour together with hormones at concentration corresp onding to their level in the first and third trimester of pregnancy. An interaction of neutrophils with commensal E. coli TG1 and uropathogenic E. coli DL82 (UPEC) biofilms was assessed 1 hour later. The biofilm biomass, activity of myeloperoxidase and cathepsin G was measured spectrophotometrically on a microplate reader Synergy H1 (BioTec, USA). Neutrophils conditioned with chorionic gonadotropin (10; 100 IU/ml), estriol (2; 20 ng/ml) and leptin (10 ng/ml) were found to enhance their potential to destroy solely opsonized commensal E. coli biofilm, without affecting the UPEC biofilm. The biomass of non-opsonized biofilm of commensal E. coli TG1 decreased after interaction with neutrophils conditioned with estriol (2 ng/ml), kisspeptin (9.6 pM) and ghrelin (0.83 ng/ml). In contrast, non-opsonized UPEC biofilm was more destroyed by neutrophils exposed to low- vs. high-dose chorionic gonadotropin (10 IU/ml and 100 IU/ml, respectively) or control group. Myeloperoxidase secretion increased when UPEC interacted with neutrophils conditioned with estriol at concentration of 2 ng/ml. Comparing the two E. coli strains allowed to find that chorionic gonadotropin (10 IU/ml) and estriol (20 ng/ml) enhanced activity of neutrophil myeloperoxidase after interaction with UPEC biofilms to a greater extent than with E. coli TG1 biofilms. Estriol (20 ng/ml) and kisspeptin (9 pM) reduced activity of neutrophil cathepsin G after interaction with UPEC biofilms.