Lacticaseibacillus casei in Diet of Juvenile Convict Cichlid Fish (Amatitlania nigrofasciata): Evaluating Growth Performance, Digestive Enzyme Activities, Immune Responses, and Stress Resistance

Lactobacillus casei (IBRC-M 10,711) ameliorates the growth retardation, oxidative stress, and immunosuppression induced by malathion toxicity in goldfish (Carassius auratus)

Probiotics can functionality improve fish wellbeing and are suggested as antioxidative agents to protect fish from xenobiotics toxicity. Herein, dietary Lactobacillus casei (IBRC-M 10,711) was included in the diets of goldfish (Carassius auratus) to protect against malathion toxicity. Fish (12.47 ± 0.06 g) were randomly allocated to six groups (triplicates), as follows: T1) control; T2) fish exposed to 50% of malathion 96 h LC50; T3) L. casei at 106 CFU/g diet; T4) L. casei at 107 CFU/g diet; T5) fish exposed to 50% of malathion 96 h LC50 + L. casei at 106 CFU/g diet; T6) fish exposed to 50% of malathion 96 h LC50 + L. casei at 107 CFU/g diet. After 60 days, goldfish fed T4 had the highest final body weight (FBW), weight gain (WG), and specific growth rate (SGR), and the lowest feed conversion ratio (FCR) among the groups (P < 0.05). However, the T2 group showed lower FBW, WG, and SGR and higher FCR than fish in T1 (P < 0.05). Fish in the T4 group had the highest blood total proteins, albumin, and globulin, while fish in T2 had the lowest levels (P < 0.05). Fish in the group T2 had the highest triglycerides, cholesterol, cortisol, lactate dehydrogenase (LDH), alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) levels in the blood, while fish fed T4 had the lowest values (P < 0.05). The superoxide dismutase (SOD) and catalase (CAT) showed the highest activities in T3 and T4 groups, and the lowest SOD was seen in the T2 group, whereas the lowest CAT was seen in the T2, T5, and T6 groups (P < 0.05). Fish in the T5 and T6 groups had higher glutathione peroxidase (GSH-Px) activities than fish in T1 and T2 groups but T3 and T4 groups showed the highest values (P < 0.05). T2 group had the highest malondialdehyde (MDA) level, while T3 and T4 groups had the lowest MDA level (P < 0.05). Blood immunoglobulin (Ig) and lysozyme activity were significantly higher in T3 and T4 groups and lower in the T2 group than in the control (P < 0.05). The alternative complement pathway (ACH50) was significantly higher in T2, T3, T4, T5, and T6 groups than in the T1 group (P < 0.05). Skin mucus Ig was significantly higher in T3 and T4 groups and lower in the T2 group than in the control (P < 0.05). The highest lysozyme activity, protease, and ACH50 in the skin mucus samples were in the T4 group, while the lowest values were in the T2 group (P < 0.05). In conclusion, dietary L. casei protects goldfish from malathion-induced growth retardation, oxidative stress, and immunosuppression.

Biological Functions of Exopolysaccharides from Lactic Acid Bacteria and Their Potential Benefits for Humans and Farmed Animals

Lactic acid bacteria (LAB) synthesize exopolysaccharides (EPS), which are structurally diverse biopolymers with a broad range of technological properties and bioactivities. There is scientific evidence that these polymers have health-promoting properties. Most commercialized probiotic microorganisms for consumption by humans and farmed animals are LAB and some of them are EPS-producers indicating that some of their beneficial properties could be due to these polymers. Probiotic LAB are currently used to improve human health and for the prevention and treatment of specific pathologic conditions. They are also used in food-producing animal husbandry, mainly due to their abilities to promote growth and inhibit pathogens via different mechanisms, among which the production of EPS could be involved. Thus, the aim of this review is to discuss the current knowledge of the characteristics, usage and biological role of EPS from LAB, as well as their postbiotic action in humans and animals, and to predict the future contribution that they could have on the diet of food animals to improve productivity, animal health status and impact on public health.