Effects of food wastes on yellow mealworm Tenebriomolitor larval nutritional profiles and growth performances

In this study, nutritional profiles and growth performances of yellow mealworm, Tenebriomolitor larvae (TML) were assessed cultivated using common food wastes i.e. watermelon rinds, broilers’ eggshells and banana peels. Nutritional profiles and growth performance of TML were evaluated after 28-day feeding trial. Post-feeding proximate analysis showed significant increment of nutritional contents compared to the control groups; whereby TML demonstrated highest level of crude protein (43.38%±2.71), moisture (9.74%±0.23) and ash (4.40%±0.22) in the group treated with watermelon wastes. On the other hand, TML showed highest level of crude fibre (8.73%±0.05) when treated with broilers’ eggshells; and higher level of crude fat (40.13%±4.66) with banana wastes. Nitrogen-free extract (NFE) contents were also noticed higher in the group treated with banana wastes (4.46%±5.30). In terms of growth performance, TML administrated with watermelon wastes demonstrated superior in specific growth rate (2.50%±0.43) and feed conversion efficiency (0.10%±0.01). Interestingly, TML grown with banana wastes showed highest survival rate (97.5%) among all. In short, TML cultivation using watermelon and banana wastes showed a promising result on nutritional fortification and growth enhancement

Gut immune system and the implications of oral-administered immunoprophylaxis in finfish aquaculture

The gastrointestinal immune system plays an important role in immune homeostasis regulation. It regulates the symbiotic host-microbiome interactions by training and developing the host’s innate and adaptive immunity. This interaction plays a vital role in host defence mechanisms and at the same time, balancing the endogenous perturbations of the host immune homeostasis. The fish gastrointestinal immune system is armed with intricate diffused gut-associated lymphoid tissues (GALTs) that establish tolerance toward the enormous commensal gut microbiome while preserving immune responses against the intrusion of enteric pathogens. A comprehensive understanding of the intestinal immune system is a prerequisite for developing an oral vaccine and immunostimulants in aquaculture, particularly in cultured fish species. In this review, we outline the remarkable features of gut immunity and the essential components of gut-associated lymphoid tissue. The mechanistic principles underlying the antigen absorption and uptake through the intestinal epithelial, and the subsequent immune activation through a series of molecular events are reviewed. The emphasis is on the significance of gut immunity in oral administration of immunoprophylactics, and the different potential adjuvants that circumvent intestinal immune tolerance. Comprehension of the intestinal immune system is pivotal for developing effective fish vaccines that can be delivered orally, which is less labour-intensive and could improve fish health and facilitate disease management in the aquaculture industry

Dietary hydrolyzable tannins reduce growth performance and induce histological damage of Chinese seabass (Lateolabrax maculatus)

Chinese seabass (Lateolabrax maculatus) is a popular carnivorous fish with delicious taste. Although the feed value of condensed tannins has been well documented for L. maculatus, information about the effects of hydrolyzable tannins (HTs) on the growth and health of L. maculatus is limited. This study was conducted to assess the effects of dietary HTs on growth performance, body composition, intestinal digestive enzyme activities, serum metabolites, antioxidant and immune response, and intestine and liver morphology of L. maculatus. A total of 640 fish were randomly divided into four groups with four replicates per group and 40 fish per replicate. Four diets were prepared to contain 0 (G0), 1 (G1), 2 (G2), and 4 (G4) g/kg of HTs. Fish were fed to apparent satiation twice a day during the 56-day feeding trial. Results showed that the final body weight, weight gain rate, specific growth rate, and feed intake were linearly decreased (p< 0.001) as dietary HTs increased. All fish had similar (p > 0.05) whole body compositions. Fish fed G2 and G4 had lower (p< 0.05) intestinal trypsin and lipase activities than those fed G0 and G1, whereas G4 had higher (p< 0.05) aspartate aminotransferase and alanine aminotransferase activities than G0. Serum total antioxidant capacity and lysozyme were linearly decreased (p< 0.01), but the malondialdehyde concentration was linearly increased (p< 0.01) as dietary HTs increased. Intestinal villi in G2 and G4 showed increased deformation, and the vacuolation of liver cells began to appear in G1 and was aggravated as dietary HTs increased. This study showed that HTs should be used with caution due to their growth-inhibiting effect, and the dietary HT level for L. maculatus is recommended to be less than 1 g/kg

Effects of lignosulfonates on callus proliferation and shoot induction of recalcitrant indica rice

In vitro culture of recalcitrant indica rice cultivar through intervening callus is difficult due to long regeneration period. Therefore, this study was undertaken to evaluate the growth promoting effects of lignosulfonate (LS) on callus proliferation and shoot induction of Malaysian recalcitrant indica rice cv. MR219. LS is a by-product of wood industry, commonly used as a plant growth enhancer. Seed derived calli were proliferated on Murashige and Skoog (MS) medium supplemented with different ion-chelated LS (calcium LS: CaLS and sodium LS: NaLS) at 50, 100, 150, and 200 mg/L. MS supplemented with 100 mg/L CaLS significantly increased the callus proliferation rate and adventitious root formation. In shoot induction study, both LSs did not enhance the shoot induction efficiency as compared to the control. However, the formation of albino shoot increased in MS fortified with 100 mg/L CaLS. Further chlorophyll and molecular analyses showed that, albino shoots induced from 100 mg/L CaLS had severe reduction in total chlorophyll content and expression of both chlorophyll-associated genes, chlorophyll a/b-binding protein 1 (OsCAB1R) and young seedling albino (OsYSA). Taken together, LS improves callus proliferation rate and modulate different physiological responses during plant growth of recalcitrant indica rice

Effects of lignosulfonates on callus proliferation and shoot induction of recalcitrant Indica rice

In vitro culture of recalcitrant indica rice cultivar through intervening callus is difficult due to long regeneration period. Therefore, this study was undertaken to evaluate the growth promoting effects of lignosulfonate (LS) on callus proliferation and shoot induction of Malaysian recalcitrant indica rice cv. MR219. LS is a by-product of wood industry, commonly used as a plant growth enhancer. Seed derived calli were proliferated on Murashige and Skoog (MS) medium supplemented with different ion-chelated LS (calcium LS: CaLS and sodium LS: NaLS) at 50, 100, 150, and 200 mg/L. MS supplemented with 100 mg/L CaLS significantly increased the callus proliferation rate and adventitious root formation. In shoot induction study, both LSs did not enhance the shoot induction efficiency as compared to the control. However, the formation of albino shoot increased in MS fortified with 100 mg/L CaLS. Further chlorophyll and molecular analyses showed that, albino shoots induced from 100 mg/L CaLS had severe reduction in total chlorophyll content and expression of both chlorophyll-associated genes, chlorophyll a/b-binding protein 1 (OsCAB1R) and young seedling albino (OsYSA). Taken together, LS improves callus proliferation rate and modulate different physiological responses during plant growth of recalcitrant indica rice

Sterile alpha and TIR motif-containing protein 1 is a negative regulator in the anti-bacterial immune responses in nile tilapia (Oreochromis niloticus)

Nile tilapia (Oreochromis niloticus) is one of the most important food fish in the world. However, the farming industry has encountered significant challenges, such as pathogen infections. Toll-like receptors (TLRs) play an essential role in the initiation of the innate immune system against pathogens. Sterile alpha and TIR motif-containing protein 1 (SARM1) is one of the most evolutionarily conserved TLR adaptors, and its orthologs are present in various species from worms to humans. SARM1 plays an important role in negatively regulating TIR domain-containing adaptor proteins inducing IFNβ (TRIF)-dependent TLR signaling in mammals, but its immune function remains poorly understood in fish. In this study, O. niloticus SARM1 (OnSARM1) was cloned and its evolutionary status was verified using bioinformatic analyses. mRNA expression of OnSARM1 was found at a higher level in the trunk kidney and muscle in healthy fish. The examination of its subcellular location showed that the OnSARM1 was detected only in the cytoplasm of THK cells, and colocalized with OnMyD88, OnTRIF and OnTRIF in small speckle-like condensed granules. The transcript levels of OnMyD88, OnTIRAP, OnTRIF, and downstream effectors, including interleukin (IL)-1β, IL-8, IL-12b and type I interferon (IFN)d2.13, were regulated conversely to the expression of OnSARM1 in the head kidney from Aeromonas hydrophila and Streptococcus agalactiae infected fish. Moreover, the treatment of THK cells with lysates from A. hydrophila and S. agalactiae enhanced the activity of the NF-κB promoter, but the effects were inhibited in the OnSARM1 overexpressed THK cells. Overexpression of OnSARM1 alone did not activate the NF-κB-luciferase reporter, but it suppressed OnMyD88- and OnTIRAP-mediated NF-κB promoter activity. Additionally, OnSARM1 inhibited the mRNA expression of proinflammatory cytokines and hepcidin in A. hydrophila lysate stimulated THK cells. Taken together, these findings suggest that OnSARM1 serves as a negative regulator by inhibiting NF-κB activity, thereby influencing the transcript level of proinflammatory cytokines and antimicrobial peptides in the antibacterial responses

Bioencapsulation and Colonization Characteristics of Lactococcus lactis subsp. lactis CF4MRS in Artemia franciscana: a Biological Approach for the Control of Edwardsiellosis in Larviculture

Predominance of beneficial bacteria helps to establish a healthy microbiota in fish gastrointestinal system and thus to reduce emerging pathogen. In this study, the colonization efficacy of Lactococcus lactis subsp. lactis CF4MRS in Artemia franciscana and its potential as a probiotic in suppressing Edwardsiella sp. infection were investigated in vivo. The colonization extent of the bioencapsulated L. lactis was established through visualization of gfp gene-transformed L. lactis in A. franciscana. Here, we demonstrate that when A. franciscana is administrated with L. lactis at 108 CFU mL−1 for 8 h, the highest relative percentage of survival (RPS = 50.0) is observed after inoculation with Edwardsiella sp. The total counts of L. lactis entrapped in Artemia were the highest (ranged from 3.2 to 5.1 × 108 CFU mL−1), when 108–109 CFU mL−1 of L. lactis was used as starting inoculum, with the bioencapsulation performed within 8–24 h. Fluorescent microscopy showed gfp-transformed L. lactis colonized the external trunk surfaces, mid-gut and locomotion antennules of the A. franciscana nauplii. These illustrations elucidate the efficiency of colonization of L. lactis in the gastrointestinal tract and on the body surfaces of Artemia. In conclusion, L. lactis subsp. lactis CF4MRS shows a good efficacy of colonization in Artemia and has the potential for biocontrol/probiotic activity against Edwardsiella sp. infection

Bioencapsulation and disease suppression studies of beneficial bacteria against Edwardsiella tarda infection in climbing perch larvae (Anabas testudineus, Bloch)

This study aimed to develop the best bioencapsulation condition for potential probiotic bacteria to control Edwardsiella tarda infection in climbing perch, Anabas testudineus larvae. Preliminary metagenomic analyses unveiled the pathogenic bacteria (e.g. Edwardsiella tarda, Pseudomonas fluorescens and Serratia marcescens) and beneficial bacteria (e.g. Bacillus subtilis) were the natural microflora in the climbing perch gastrointestinal (GI) tract. Compared to other pathogens, E. tarda was largely residing in the wild- and farmed-typed A. testudineus GI tract. Multiple in vitro screenings such as antagonistic, hemolytic, antibiotic and bacteriosin-like substance (BLIS) assays were performed in the study to determine the best probiotic against E. tarda, through isolating and evaluating the microflora isolated from intestines of Oreochromis niloticus, Clarias batrachus, Ophicephalus striatus, Trichogaster pectoralis, Anabas testudineus and Pangasius pangasius. Data suggested that L. lactis subsp. lactis (CF4MRS) at > 106 CFU mL-1 could be effectively used to control E. tarda in laboratory condition. This bacterial isolate also showed a strong antimicrobial activity against other fish pathogens such as P. fluorescens, P. aeruginosa, K. pneumonia, E. coli, A. hydrophila, and S. marcescens. HPLC analysis showed that this antimicrobial activity was not attributed to any compounds but the organic acids i.e. lactic acid. When L. lactis subsp. lactis CF4MRS (108 CFU mL-1) was bioencapsulated in Artemia franciscana, it could be effectively used to protect the live feed against E. tarda up to 50% of survival rate. Colonization efficiency of the probiotic was also highly demonstrated in A. franciscana when gfp-transformed L. lactis was used in the bioencapsulation process. In addition, this probiotic also improve the production of amylase, protease, lipase and cellulase enzymes in A. franciscana. For the best bacterial encapsulation result, sodium alginate was suggested in the A. franciscana bioencapsulation instead of starch, gum Arabic and gelatin, as it showed the highest total bacterial count in Artemia (2.44 × 107 CFU mL-1). To determine the effects of the probiotic on climbing perch larvae, A. testudineus larvae were produced by comparing different hormones (LHRHa and SGnRHa). Results suggested induced breeding using LHRHa was the most effective way to produce the fish larvae. In the in vivo pathogenic assays, fish larvae were divided into various groups: Artemia nauplii enriched with 108 CFU mL-1 L. lactis (LA); Nauplii enriched 0.5 g L-1 sodium alginate (SA); Nauplii enriched 0.5 g L-1 sodium alginate containing 108 CFU mL-1 L. lactis (LSA); and nauplii only as the control (A). Fish larvae fed with LSA showed highest larval survival rate (50%) compared to LA (41.7%), SA (31.7%) and A (20%). Lysozyme activity was also highest in LSA (13.89 units mg-1 protein), followed by LA (10.00 units mg-1 protein), SA (8.33 units mg-1 protein) and A (1.33 units mg-1 protein). The result indicated a strong improvement of immune response in fish larvae when LSA was included in larval diet. In a nutshell, combination of L. lactis CF4MRS (108 CFU mL-1 for 8 h) and alginate in Artemia bioencapsulation could improve survival rate of E. tarda-infected climbing perch larvae through up-regulating their innate immune response

Bioencapsulation and disease suppression studies of beneficial bacteria against Edwardsiella tarda infection in climbing perch larvae (Anabas testudineus, Bloch)

This study aimed to develop the best bioencapsulation condition for potential probiotic bacteria to control Edwardsiella tarda infection in climbing perch, Anabas testudineus larvae. Preliminary metagenomic analyses unveiled the pathogenic bacteria (e.g. Edwardsiella tarda, Pseudomonas fluorescens and Serratia marcescens) and beneficial bacteria (e.g. Bacillus subtilis) were the natural microflora in the climbing perch gastrointestinal (GI) tract. Compared to other pathogens, E. tarda was largely residing in the wild- and farmed-typed A. testudineus GI tract. Multiple in vitro screenings such as antagonistic, hemolytic, antibiotic and bacteriosin-like substance (BLIS) assays were performed in the study to determine the best probiotic against E. tarda, through isolating and evaluating the microflora isolated from intestines of Oreochromis niloticus, Clarias batrachus, Ophicephalus striatus, Trichogaster pectoralis, Anabas testudineus and Pangasius pangasius. Data suggested that L. lactis subsp. lactis (CF4MRS) at > 106 CFU mL-1 could be effectively used to control E. tarda in laboratory condition. This bacterial isolate also showed a strong antimicrobial activity against other fish pathogens such as P. fluorescens, P. aeruginosa, K. pneumonia, E. coli, A. hydrophila, and S. marcescens. HPLC analysis showed that this antimicrobial activity was not attributed to any compounds but the organic acids i.e. lactic acid. When L. lactis subsp. lactis CF4MRS (108 CFU mL-1) was bioencapsulated in Artemia franciscana, it could be effectively used to protect the live feed against E. tarda up to 50% of survival rate. Colonization efficiency of the probiotic was also highly demonstrated in A. franciscana when gfp-transformed L. lactis was used in the bioencapsulation process. In addition, this probiotic also improve the production of amylase, protease, lipase and cellulase enzymes in A. franciscana. For the best bacterial encapsulation result, sodium alginate was suggested in the A. franciscana bioencapsulation instead of starch, gum Arabic and gelatin, as it showed the highest total bacterial count in Artemia (2.44 × 107 CFU mL-1). To determine the effects of the probiotic on climbing perch larvae, A. testudineus larvae were produced by comparing different hormones (LHRHa and SGnRHa). Results suggested induced breeding using LHRHa was the most effective way to produce the fish larvae. In the in vivo pathogenic assays, fish larvae were divided into various groups: Artemia nauplii enriched with 108 CFU mL-1 L. lactis (LA); Nauplii enriched 0.5 g L-1 sodium alginate (SA); Nauplii enriched 0.5 g L-1 sodium alginate containing 108 CFU mL-1 L. lactis (LSA); and nauplii only as the control (A). Fish larvae fed with LSA showed highest larval survival rate (50%) compared to LA (41.7%), SA (31.7%) and A (20%). Lysozyme activity was also highest in LSA (13.89 units mg-1 protein), followed by LA (10.00 units mg-1 protein), SA (8.33 units mg-1 protein) and A (1.33 units mg-1 protein). The result indicated a strong improvement of immune response in fish larvae when LSA was included in larval diet. In a nutshell, combination of L. lactis CF4MRS (108 CFU mL-1 for 8 h) and alginate in Artemia bioencapsulation could improve survival rate of E. tarda-infected climbing perch larvae through up-regulating their innate immune response

Feasibility of vaccination against Macrobrachium rosenbergii nodavirus infection in giant freshwater prawn

The giant freshwater prawn/giant river prawn, Macrobrachium rosenbergii is one of the high market value crustaceans cultured worldwide. The intensified aquaculture of the species has led to the outbreak of infectious diseases, prominently, the white tail disease (WTD). It is caused by the infection of Macrobrachium rosenbergii nodavirus (MrNV), which was classified in the family of Nodaviridae. To-date, there are no effective prophylactic and therapeutic agents available against MrNV infection. Vaccination is known to be the most effective prophylactic agent in disease prevention. However, vaccine development against virus infection in crustaceans is equivocal. The feasibility of vaccination in conferring immune protection in crustaceans against infectious diseases is disputable. The argument lies in the fact that crustaceans do not possess adaptive immunity, which is the main immune component that functions to establish immunological memory upon vaccination. Nevertheless, an increasing number of literatures has been documented, which concerns the development of vaccines against infectious diseases in crustaceans. The current review deliberates different approaches in vaccine development against MrNV, which were documented in the past years. It is noteworthy that the live-attenuated MrNV vaccine has not been experimented by far. Thus, the potential of live-attenuated MrNV vaccine in conferring long-term immune protection through the establishment of innate immune memory is currently being discussed