Comparative genomics of Photobacterium species from terrestrial and marine habitats

Photobacterium (P.) is a genus widely studied in regards to its association with and ubiquitous presence in marine environments. However, certain species (P. phosphoreum, P. carnosum, P. iliopiscarium) have been recently described to colonize and spoil raw meats without a marine link. We have studied 27 strains from meat as well as 26 strains from marine environments in order to probe for intraspecies marine/terrestrial subpopulations and identify distinct genomic features acquired by environmental adaptation. We have conducted phylogenetic analysis (MLSA, ANI, fur, codon usage), search of plasmids (plasmidSPADES), phages (PHASTER), CRISPR-cas operons (CRISPR-finder) and secondary metabolites gene clusters (antiSMASH, BAGEL), in addition to a targeted gene search for specific pathways (e.g. TCA cycle, pentose phosphate, respiratory chain) and elements relevant for growth, adaptation and competition (substrate utilization, motility, bioluminescence, sodium and iron transport). P. carnosum appears as a conserved single clade, with one isolate from MAP fish clustering apart that doesn't, however, show distinct features that could indicate different adaptation. The species harbors genes for a wide carbon source utilization (glycogen/starch, maltose, pullulan, fucose) for colonization of diverse niches in its genome. P. phosphoreum is represented by two different clades on the phylogenetic analyses not correlating to their origin or distribution of other features analyzed that can be divided into two novel subspecies based on genome-wide values. A more diverse antimicrobial activity (sactipeptides, microcins), production of secondary metabolites (siderophores and arylpolyenes), stress response and adaptation (bioluminescence, sodium transporters, catalase, high affinity for oxygen cytochrome cbb3 oxidase, DMSO reductase and proton translocating NADH dehydrogenase) is predicted compared to the other species. P. iliopiscarium was divided into two clades based on source of isolation correlating with phylogeny and distribution of several traits. The species shows traits common to the other two species, similar carbon utilization/transport gene conservation as P. carnosum for the meat-isolated strains, and predicted utilization of marine-common DMSO and flagellar cluster for the sea-isolated strains. Results additionally suggest that photobacteria are highly prone to horizontal acquisition/loss of genetic material and genetic transduction, and that it might be a strategy for increasing the frequency of strain- or species-specific features that offers a growth/competition advantage.

Fatty acid levels in the muscle tissue of eight beef cattle breeds

The objective of the study was to compare the chemical composition and fatty acid profile in ten clinically healthy bulls of similar weight from eight meat cattle breeds. The animals were raised by extensive grazing under the same geographical conditions. Significant differences were observed between the monitored genotypes in terms of the dry matter content, nitrogenous matter and fats (P ≤ 0.05) in the musculus longissimus thoracis. The concentration of fats ranged from 68.5 ± 18.81 g (Galloway cattle) to 171.6 ± 43.3 g (Aberdeen Angus) per kg of dry matter. The total content of unsaturated fatty acids ranged from 20.0 ± 2.25 g (Aberdeen Angus) to 42.4 ± 7.87 g (Gascon); the total sum of monounsaurated fatty acids ranged from 17.0 ± 2.26 g (Aberdeen Angus) to 33.8 ± 3.61 g (Gascon); and the total sum of polyunsaturated fatty acids ranged from 3.0 ± 1.42 g (Aberdeen Angus) to 5.1 ± 3.99 g (Limousin) per 100 g of fat. The total content of n-6 fatty acids ranged from 2.4 ± 1.28 g (Aberdeen Angus) to 4.2 ± 3.59 g (Limousin) and the total content of n-3 fatty acids from 0.5 ± 0.16 g (Salers) to 1.1 ± 0.04 g (Gascon) per 100 g of fat. The properties we studied may predict the biological, dietetic, and culinary value of the meat.

Variation of meat quality parameters due to conformation and fat class in limousin bulls slaughtered at 25 to 27 months of age

The aim of the present study was to determine the influence of age of animal, hot carcass weight, pH, conformation and fat class on basic beef quality attributes (tenderness, sarcomere length, basic chemical composition, marbling and colour) in a group of purebred animals. The object of the study was beef of Limousin bulls (25 to 27 months, hot carcass weight - 432±31 kg, “U” conformation class, “2”–“3” fat class). Analysed cuts were Infraspinatus muscle from the blade and Longissimus dorsi muscle from the cube roll and the striploin. Tenderness was analysed with universal testing machine, colour - chromometer analysis, sarcomere length - microscopic method, basic chemical composition - near-infrared spectroscopy and marbling - computer image analysis. No differences in tenderness and sarcomere length were observed within the age groups of Limousin bulls (age of 25, 26, 27 months) (p>0.05). Moisture (p = 0.0123) and fat (p = 0.0250) content were significantly different for meat of animals slaughtered at the age of 25 and 27 months. No influence of pH value on tenderness was observed, but at the same time, influence on sarcomere length (p = 0.039) and b* component of colour (0.045) was found. For “U” conformation class, in subclasses, as well as for fat classes “2”–“3”, there were no differences in tenderness, sarcomere length and colour components. Higher fat content was observed in the higher fat class, rather than in lower, however this feature was not associated with marbling.