Determination of Zn, Fe, Cr and Cu in Marine Fish Commonly Consumed in Senegal

The content of four heavy metals (zinc, iron, chromium and copper) in muscles, liver and gonads has been studied for the five most consumed fish species (Cephalopholus taeniops, Scomber japonicus, Lagocephalus laevigatus, Pagellus bellottii and Pagrus caeruleostictus) in the Soumbedioune region. The samples were digested by acid digestion. The metal contents were quantified using a PF-11 type photometer. The results obtained show that metals such as zinc, iron and chromium are significantly higher (p <0.05) in the muscles of the four species than in the liver and gonads. However, the levels of heavy metals in the muscles, liver, and gonads of the five species are above the acceptable limit recommended by the FAO and WHO, with the exception of the copper levels in the gonads of the species Pagellus bellottii.

An analysis of historical landing data of some pelagic species caught by purse seines in the Aegean Sea

The fishing activity with purse seines in the Aegean Sea accounts for almost half of the pelagic fish excluding anchovy (Engraulis encrasicolus Linnaeus, 1758) in Turkey. In this study, we aimed to analyse the catch amounts of some important pelagic species caught by Aegean purse seiners between 1973 and 2019. While mid-1990s are the most captured years for the European pilchard (Sardina pilchardus Walbaum, 1792) in Aegean Sea and also Turkish Seas, this amount has decreased at the level of 10000 mt in the mid-2000s and remained similar amounts up to now. Though European pilchard was the most caught species in the Aegean until 2011, this has changed in favour of anchovy in the last decade. Recently, almost all pelagic species such as mackerel (Scomber scombrus Linnaeus, 1758), chub mackerel (Scomber japonicus Houttuyn, 1782) and bogue (Boops boops Linnaeus, 1758) have been caught from the Aegean Sea in Turkey. In the study, the production of these species in the historical period was tried to be associated with the regulations implemented with circulars and notifications, and the problems preventing the sustainable use of these species that were caught by purse seiners were determined and solutions were proposed for the future.

Identificación de cepas bacterianas cultivables presentes en peces (caballas) utilizando un fragmento del gen 16S ARNr

El salazonado de pescado es una forma antigua y económica de preservación que se usa aún en países en vías de desarrollo como el Perú. En la región Tumbes, es común la comercialización de caballa (Scomber japonicus peruanus) salada artesanalmente, por lo cual su inocuidad microbiológica no está garantizada. La presente investigación tuvo como objetivo identificar, mediante el secuenciamiento de un fragmento del gen 16S ARNr, las bacterias cultivables presente en la caballa salada comercializada en Tumbes. A partir de tejido del músculo de la caballa, se aislaron cepas bacterianas en medio TSA suplementado con 15% de NaCl, de las que luego se obtuvieron fragmentos del gen 16S ARNr, que fueron secuenciados para luego identificar la especie a la que pertenecieron mediante una búsqueda en Genbank. Adicionalmente se analizaron el contenido de humedad y de NaCl del músculo de la caballa salada. Como resultado se identificaron cepas típicas de productos salados como: Staphylococcus sp, Halomonas sp, Staphylococcus equorum, Salinivibrio sp, Staphylococcus nepalensis y Salinivibrio sp. Sin embargo, en el 70% de las caballas analizadas se tuvieron niveles de humedad inadecuados, así como bajos niveles de NaCl, lo cual indicó un salado inadecuado y en consecuencia un producto con pobre conservación.

Distribution, Feeding Habits, and Growth of Chub Mackerel, Scomber japonicus, Larvae During a High-Stock Period in the Northern Satsunan Area, Southern Japan

To evaluate the importance of the northern Satsunan area in southern Japan as a spawning and nursery ground for chub mackerel (Scomber japonicus), we investigated the early life history characteristics (e.g., larval distribution, feeding habits, and growth) of S. japonicus over five successive years. This area is considered the main habitat and spawning ground of the congeneric species, S. australasicus. Using polymerase chain reaction-restriction fragment length polymorphism analysis, we first confirmed that S. japonicus larvae were abundant in the northern Satsunan area, potentially representing a major spawning and nursery ground in the Japanese Pacific coastal area. The number of recorded larvae started to increase in 2016, corresponding to the population dynamics of the Pacific stock of the species, which has shown increasing trends in recent years. Morphological and DNA metabarcoding analyses of gut contents and stable isotope analysis showed that, in addition to copepods, the larvae fed substantially on appendicularians. The trophic pathway involving appendicularians might support the feeding habits of S. japonicus, promoting its coexistence with other dominant species. Both the instantaneous growth rate and daily specific growth rate were comparable to those in the southern East China Sea, which is the main spawning and nursery ground of the species. Our data strongly suggest that the northern Satsunan area has favorable conditions for sustaining high larval population densities, even during phases with high population numbers. Our results provide insights for the fisheries management for S. japonicus in the Japanese Pacific coastal area, especially during high-stock periods.

Coproduction of 5-Aminovalerate and δ-Valerolactam for the Synthesis of Nylon 5 From L-Lysine in Escherichia coli

The compounds 5-aminovalerate and δ-valerolactam are important building blocks that can be used to synthesize bioplastics. The production of 5-aminovalerate and δ-valerolactam in microorganisms provides an ideal source that reduces the cost. To achieve efficient biobased coproduction of 5-aminovalerate and δ-valerolactam in Escherichia coli, a single biotransformation step from L-lysine was constructed. First, an equilibrium mixture was formed by L-lysine α-oxidase RaiP from Scomber japonicus. In addition, by adjusting the pH and H2O2 concentration, the titers of 5-aminovalerate and δ-valerolactam reached 10.24 and 1.82 g/L from 40 g/L L-lysine HCl at pH 5.0 and 10 mM H2O2, respectively. With the optimized pH value, the δ-valerolactam titer was improved to 6.88 g/L at pH 9.0 with a molar yield of 0.35 mol/mol lysine. The ratio of 5AVA and δ-valerolactam was obviously affected by pH value. The ratio of 5AVA and δ-valerolactam could be obtained in the range of 5.63:1–0.58:1 at pH 5.0–9.0 from the equilibrium mixture. As a result, the simultaneous synthesis of 5-aminovalerate and δ-valerolactam from L-lysine in Escherichia coli is highly promising. To our knowledge, this result constitutes the highest δ-valerolactam titer reported by biological methods. In summary, a commercially implied bioprocess developed for the coproduction of 5-aminovalerate and δ-valerolactam using engineered Escherichia coli.