Iraqi Journal of Aquaculture

The current study was conducted in the laboratories of the Marine Science Center at the University of Basrah. In order to propagate lemongrass using plant tissue culture technology and test the effectiveness of leaves methanolic extract in concentrations (2.5%, 5%, 7.5%, and 10%), to demonstrate its effect in inhibiting three species of bacteria (Aeromonas sobria, Sphingomonas paucimobilis, and Sphingomonas paucimobilis Isolated from common carp (Cyprinus carpio) infected with bacterial gill disease, The bacterial types were collected from infected fish at a local fish farm in Basrah Governorate, southern Iraq, The bacterial isolates were identified chemically using VITEK II system cards, as well as genetically using 16s rRNA. The results showed that the 10% extract exhibited the highest antibacterial efficacy, while the 2.5% concentration showed the weakest activity. Notably, Aeromonas sobria strain demonstrated the greatest sensitivity to the lemongrass extract, whereas Sphingomonas paucimobilis showed complete resistance across all tested concentrations. The results of GC MS analysis indicated that the lemongrass extract contained many active compounds, including Itaconate and Eugenol, which have an antibacterial effect, Citral, Curlone, hydrazine, saponin, and all concentrations of the extracts showed varying degrees of activity against these tested bacterial species, comparable to their effectiveness with the standard antibiotic oxytetracycline.

The current study demonstrated variations in total fat content and fatty acid composition in different body parts of the Sepia pharaonis, including both the head and mantle, from three selected specimens weighing 700 ± 50g, 1566.7 ± 410.9g, and 2441.7 ± 401.9g. Fatty acid analysis showed significant differences among weight groups (P ≤ 0.05) between the groups based on weight for most of the fatty acids studied. Oleic acid was the most abundant fatty acid in the head and mantle tissues. Fatty acid analysis showed significant differences among weight groups (P ≤ 0.05) eicosapentaenoic acid (EPA), linoleic acid, linolenic acid, palmitic acid, and stearic acid showed a significant increasing trend with growth, where the largest group exhibited higher values compared to the smallest group, the intermediate group presented intermediate values, statistically indistinguishable from both the lower and higher weight groups. In contrast, docosahexaenoic acid (DHA) remained relatively stable in the head with no significant differences, whereas it showed significant variation in the mantle. the higher fatty acid concentrations in the head may be due to the different nature and functions of the tissues compared to the mantle. The mantle contains lower lipid accumulation possibly because it is mostly muscular compared to the head. Overall, the results suggest a positive relationship between body weight and lipid accumulation and clear differences in fatty acid profiles between tissues. These results emphasise the effect of growth and tissue type on the biochemical composition of S. pharaonis, with possible implications for its nutritional value and exploitation.