Responses of Atlantic cod Gadus morhua head kidney leukocytes to phytase produced by gastrointestinal-derived bacteria

Abstract

This study identified phytase-producing bacteria that were previously isolated from the gastrointestinal tract of Atlantic cod, Gadus morhua and determined its effect on head kidney leukocytes. Out of the 216 bacterial strains tested, the two phytase producers were identified as Pseudomonas sp. and Psychrobacter sp. based on their 16S rDNA sequence. Crude phytase from these two bacterial strains was produced employing the shake flask method. Even though the total protein of the crude phytase was not significantly different for the two bacteria, the phytase activity of the crude enzyme produced by Pseudomonas sp. (97.1±16.7 U) was significantly higher than that of the enzyme from Psychrobacter sp. (75.9±2.4 U). When cod head kidney leukocytes were incubated with the crude phytase (50 μg ml(-1)), it resulted in enhanced cell proliferation, higher myeloperoxidase, and acid phosphatase activities. Extracellular responses-respiratory burst activity and hydrogen peroxide production were not enhanced by the crude enzyme. As a consequence, the growth of two pathogenic bacteria Aeromonas salmonicida and Vibrio anguillarum was not suppressed by the supernatants obtained from head kidney leukocytes incubated with the crude bacterial phytase. Thus, the enzyme from phytase-producing intestinal bacteria of Atlantic cod can stimulate intracellular head kidney leukocyte activities but not the production of extracellular substances that are involved in antibacterial response. These have implications on the potential use of bacterial phytase as feed supplement to boost cellular immune response of the fish and could be employed as a health management strategy in culture systems.

Use of phytase at graded levels for improving nutrient digestibility, growth and hematology of Catla catla fingerlings fed Moringa oleifera seed meal (MOSM) based diet

“…Similarly, the values of RBCs, WBCs and Hb were found higher in Cyprinus carpio fed diets supplemeted at 500 FTU kg -1 level of phytase in soya protein based diet (Sardar et al, 2007). Encouraging results were found when phytase was used in Gadus morhua (Atlantic cod) feed which resulted in higher number of WBCs as compared to fish fed control diet (Lazado et al, 2010). Hemoglobin (Hb) level in fish fed phytase supplemented diet was slightly higher than that of fish fed a diet without phytase, but was not significantly (p<0.05) different from that of other dietary treatments (Yoo and Bai, 2014).…”

Characterization of GP21 and GP12: Two Potential Probiotic Bacteria Isolated from the Gastrointestinal Tract of Atlantic Cod

“…Previously, we found that two of these bacteria could produce phytase and therefore we attempted to characterize them for further applications. They were identified as belonging to the genera Pseudomonas (GP21) and Psychrobacter (GP12) based on their 16s rDNA sequences [20].…”

Bacterial viability differentially influences the immunomodulatory capabilities of potential host-derived probiotics in the intestinal epithelial cells of Atlantic cod Gadus morhua

“…(Lazado et al . ). These host‐derived bacteria have the capability to modulate immune responses in the head kidney leucocytes of the fish (Lazado et al .…”