Effect of Chitosan-Gelatin Composite and Bi-Layer Coating Combined with Pomegranate Peel Extract on Quality Properties of Belanger’s Croaker (Johnius Belangerii) Stored in Refrigerator

The aim of this study was to evaluate the effects of chitosan-gelatin coating with two different methods (composite and bi-layer) in combination with pomegranate peel extract (PPE) on the microbiological (mesophilic bacteria, psychrotrophic bacteria, and Enterobacteriaceae) and chemical (total volatile bases-nitrogen (TVB-N), pH, thiobarbituric acid (TBA), and free fatty acid (FFA)) properties of Belanger’s croaker (Johnius belangerii) fillets during refrigerated storage (4 ± 1°C). In this study, composite coating (CC), bilayer coating (BC), CC+PPE, and BC+PPE led to 6.88, 7.00, 6.52, and 6.32 log₁₀ CFU/g reduction in mesophilic bacteria, 6.67, 7.02, 5.35, and 4.21 log₁₀ CFU/g in PTC and 2.99, 2.71, 2.37, and 2.41 log₁₀ CFU/g, compared with control sample for 16 days storage time, respectively. Chitosan-gelatin coating enriched with PPE has retarding effects on spoilage of fish samples, thus extending the shelf life during refrigerated storage. The quality characteristics of croaker treated with chitosan-gelatin coating combined with PPE were better than those treated by chitosan-gelatin coating or PPE alone during the storage, exhibiting that there is a synergistic effect between chitosan-gelatin coating and PPE. The bi-layer coating was better than one composite coating in combination with PPE in reducing lipid oxidation of fillets.     

Culture-independent analysis of the bacterial community during fermentation of pa-som,a traditional fermented fish product in Laos

Pa-som is a traditional salty fermented food made from varieties of freshwater fish with garlic and rice in Laos. A similar product, plaa-som, is made in Thailand. To investigate the fermentation process of pa-som, lactic acid production and pH were monitored during laboratory-scale production of pa-som. Furthermore, the variety of bacteria involved and their succession during fermentation were examined using culture-independent polymerase chain reaction (PCR) denaturing gel gradient electrophoresis targeting the 16S ribosomal RNA (rRNA) gene. d- and l-lactic acid production and a decrease in pH were observed in the samples after 1 day of fermentation. The lactic acid content and pH continued to increase and decrease, respectively, until 4 days of fermentation. Overall, six lactic acid bacteria and eight other indigenous bacteria species were detected during pa-som fermentation. Among the lactic acid bacteria detected, two Lactococcus and one Weissella species were detected in samples after 1–4 days of fermentation, suggesting that these three species play major roles in pa-som fermentation from the initial phase. This is the first report to investigate the fermentation process in pa-som at the microbial level. This research approach should be applicable to a wide variety of pa-som and related fermented fishery products in Laos to help understand their microbial diversity and to identify beneficial bacterial species for improving quality.     

凡纳滨对虾白便综合征发生与环境因子、机体免疫酶活性和微生物的相关性

为系统解析凡纳滨对虾白便综合征 (white feces syndrome,WFS)的发生与环境因子、微生物因子、宿主免疫力和水体微生物群落组成的关系。实验利用水体理化因子、可培养细菌、对虾机体免疫酶活性以及高通量测序等检测技术对健康与患WFS的池塘养殖凡纳滨对虾进行比较分析。结果显示,与健康组相比,患病池塘的水温、溶解氧 (DO)、pH、盐度等水质理化因子波动趋势相似,波动范围分别为26.1~29.0 °C、4.26~6.08 mg/L、8.39~8.73和40~49,患病组DO和盐度比健康组高;健康组对虾肝胰腺内可培养细菌和弧菌含量为1.19×10⁵~7.70×10⁵和8.8×10³~1.96×10⁴ CFU/g,弧菌占比为2%~16%,患病组对虾肝胰腺内可培养细菌和弧菌含量在3.80×10⁵~2.51×10⁶和2.02×10⁵~1.49×10⁶ CFU/g范围内,比健康组高15~113倍,弧菌占比在55%~70%。碱性磷酸酶 (AKP)、酸性磷酸酶 (ACP)、溶菌酶 (LZM)、超氧化物歧化酶 (SOD)和酚氧化酶 (PO)活性在健康组内为1.21~5.64、9.17~15.25、3.56~7.43、4.83~6.70及3.10~4.55 U/mg,在患病组内为2.12~5.39、19.22~26.96、19.73~26.85、3.00~4.14及7.76~9.21 U/mg。比较分析表明,WFS的发生与可培养细菌含量、弧菌占比、ACP、LZM、PO的相关性较强。高通量测序分析表明,患病组水体菌群结构的Ace和Chao指数呈一定程度下降趋势,PCoA指数偏离度较高,放线菌门、变形菌门相对丰度降低,拟杆菌门、蓝藻门相对丰度显著升高;RDA关联分析表明,盐度、溶解氧、虾体细菌、虾体弧菌、水体细菌是影响患病对虾水体菌群结构组成的重要因子。相关研究结果为解析养殖生产中对虾WFS发生机制提供数据支撑,并为WFS的临床防控奠定理论基础。     

Alginate coarse/nanoemulsions containing Zataria multiflora Boiss essential oil as edible coatings and the impact on microbial quality of trout fillet

In this study, the effect of edible coarse/nanoemulsions of alginate as coating containing Zataria multiflora Boiss essential oil (ZEO) on the microbial quality of fish fillets was investigated at three concentrations (i.e. 0.25%, 0.5% and 1% [w/v]) in 16 days of storage at 4°C. Moreover, a comparison was made between the fabricated coarse emulsion and nanoemulsion coatings by particle size and polydispersity index analyses. Sample analysis was performed with regard to total viable count (TVC), total psychrophilic count (TPC), hydrogen sulphide‐producing bacteria count (HSC) and Enterobacteriaceae count (ENC) on days 0, 4, 8, 12 and 16. According to the findings, all the samples showed increased microbial counts during the storage periods. The highest reduction rates of TVC (about 2 log CFU/g), TPC (about 1 log CFU/g), HSC (about 1.5 log CFU/g) and ENC (about 3 log CFU/g) were observed in the nanoemulsion of alginate containing 1% w/v ZEO (NE 1%) samples, compared with alginate and control samples. The microbial growth was significantly inhibited in all treatments, compared with that in the control (p < .05). Accordingly, it can be concluded that nanoemulsion coating was more effective than coarse emulsion to prolong the durability of fish fillets and revealed a faster and greater inhibition of microbial flora, compared with coarse emulsions during the storage time.     

A Microbial Fermentation of Soybean and Cottonseed Meal Increases Antioxidant Activity and Gossypol Detoxification in Diets for Nile tilapia,Oreochromis niloticus

We report the beneficial effects of a microbial fermentation process of plant protein sources. To reduce anti‐nutritional factors, soybean meal (SM) and cottonseed meal (CM) were fermented with Aspergillus oryzae, a probiotic microorganism, and a 12‐wk feeding study was conducted to evaluate the supplemental effects of the fermented soybean meal (FSM) or fermented cottonseed meal (FCM) in diets for juvenile Nile tilapia. Growth performance and hematological parameters were not influenced by the fermentation process, while the highest inclusion of both FSM and FCM lowered feed utilization efficiency. The microbial fermentation significantly increased dietary total polyphenols and consequently led to higher 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activities in both diets and fish tissue. Dietary and liver gossypol concentrations were significantly decreased by the fermentation process of CM. The findings suggest that microbial fermentation of SM or CM with A. oryzae can enhance antioxidant activities in diets and fish, and effectively reduce or degrade the toxicity of gossypol present in CM. A microbial fermentation could make plant protein sources more useful and functional in feeds for fish.     

Effect of Chitosan and Garlic Essential Oil on Microbiological and Biochemical Changes that Affect Quality in Grass Carp (Ctenopharyngodon idellus) Fillets During Storage at 4°C

Solutions of chitosan (2%, w/v), garlic essential oil (5%, v/v), and their combination (2%, w/v chitosan +5%, v/v garlic essential oil) were applied to the surface of grass carp fillets. Subsequently, sensory, microbiological analyses (total viable count (TVC), Pseudomonas spp., Aeromonas spp., and H₂S-producing bacteria), and physicochemical changes (total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), and centrifugation loss) of grass carp fillets were evaluated over a 16-day storage at 4 ± 1°C. The treated samples resulted in significantly (p < 0.05) higher overall acceptance scores than the control from day 8. The TVC of grass carp fillets was reduced from the initial level (4.0 log CFU/g) to 2–3 log CFU/g when the fillets were treated with either garlic essential oil or chitosan solution. After 4 days of storage, the Pseudomonas spp. counts in the chitosan-treated samples were significantly lower (p < 0.05) than the counts in control and samples treated with garlic essential oil. A lag phase of 6 days for the counts of H₂S-producing bacteria of fish fillets that were treated with chitosan or the combination solution was observed. The combination of chitosan with garlic essential oil did not show synergistic effects, although it displayed a higher degree of antimicrobial efficacy with respect to the spoiled bacteria. However, the combination of chitosan with garlic essential oil was the most effective at inhibiting the formation of TVB-N. Samples that were treated with garlic essential oil displayed the highest TBARS levels on days 4 and 6 (p < 0.05).     

Response of Bacterial Biofilms in Recirculating Aquaculture Systems to Various Sanitizers

ABSTRACT

Pathogenic microorganisms may be incorporated into biofilms found in aquaculture systems, causing recurring exposure to potential disease agents. Aerobic plate counts, the presence of Enterobacteriaceae, and the presence of Escherichia coli, modified to express a green fluorescent protein (GFP E. coli), was used to evaluate the effectiveness of various sanitizers in decreasing bacterial incorporation into newly generated biofilms in recirculating aquaculture systems. Disks of Buna-N rubber, polyvinyl chloride (PVC), chlorinated PVC, glass, fiberglass, and stainless steel were placed in aquariums stocked with Nile tilapia, Oreochromis niloticus. The effectiveness of water, an alkaline cleanser, sodium hypochlorite, a quaternary ammonium compound, or peracetic acid as a sanitizer was evaluated on each substrate by enumerating total plate counts, GFP E. coli, and Enterobacteriaceae. Sodium hypochlorite and peracetic acid were the most effective sanitizers, with an overall percentage reduction of GFP E. coli of approximately 2 logs₁₀. The quaternary ammonium compound was moderately effective, 1 log₁₀, against the target organisms. Water demonstrated a 2 log₁₀ reduction of the total plate count, suggesting that some mechanical cleaning was achieved. The type of material used as substrate for the biofilm had no significant (P?>?0.05) effect on the effectiveness of the sanitizers.     

Microbial Quality,Safety, and Sensory Acceptability of X-ray Treated Fresh Channel Catfish Fillets

This study was designed to determine if treatment with low dose X‐ray irradiation changes microbial quality (microbial load), safety (Listeria monocytogenes incidence), and sensory characteristics (aroma, appearance, and texture) of fresh aquacultured Channel catfish (Ictalurus punctatus) fillets during refrigerated storage. Fillets were treated to 0, 0.5, 1.0, and 1.5 kGy using an X‐ray irradiator and stored at 3°C for 17 days. Fillet aerobic plate count (APC), psychrotrophic plate count (PPC), total coliform count (TCC), and L. monocytogenes incidence were measured every 4 days during storage. A Difference-From-Control test was used to measure aroma, appearance, and texture. Fillet microbial counts were significantly different (p < 0.05) with time, irradiation dose, and the interaction of these two treatments. As expected, APC, PPC, and TCC increased as storage time increased. Overall L. monocytogenes incidence was 40%, 27%, 0%, and 7% at 0, 0.5, 1.0, and 1.5 kGy, respectively. Aroma of irradiated and non‐irradiated catfish fillets was significantly different, with greater aroma differences recorded as storage time increased due to progressional spoilage of the untreated controls. However, there were no significant aroma differences noted among the different irradiation doses. Neither appearance nor texture was significantly different between any treatments throughout testing. This study indicated that exposure to low dose X-ray irradiation improved the microbial quality and safety of fresh catfish fillets without affecting sensory acceptability at time of purchase.     

Formation of Biogenic Amines and Associated Biochemical and Microbial Attributes of Whole Sutchi Catfish (Pangasianodon hypophthalmus) during Iced Storage

Sutchi catfish (Pangasianodon hypophthalmus) is a highly preferred farmed species that is produced in huge quantities. Meat from ice-stored (4 ± 2°C) whole Sutchi catfish was evaluated for formation of biogenic amines, such as putrescine, cadaverine, histamine (HIM), agmatine, tyramine, spermine, and spermidine, and compared with biochemical, microbial, and sensory attributes during 22 days. Analysis of content of biogenic amines in the meat was carried out by liquid chromatography with tandem mass spectrometry using a without derivatization method. Three amines, namely, tyramine, spermidine, and spermine, were only present on 0^th day of storage. Presence of cadaverine was noticed from 9^th day onwards, where the aerobic plate count (APC) reached 4.85 log CFU/g. Putrescine was detected on the 22^nd day of storage, where the APC crossed 7 log CFU/g. HIM was detected in lower quantities from 3^rd day onwards. A shelf life of 15 days was determined based on sensory and microbiological evaluation. Although the samples were biochemically acceptable throughout the storage period, APC exceeded the limit on day 19, and the gradual increase of H₂S-producing bacteria, Brochothrix thermosphacta, Aeromonas, and Enterobacteriaceae, was observed during storage.     

Evaluations of lactic acid bacteria as probiotics for juvenile seabass Lates calcarifer

Lactic acid bacteria (LAB) were isolated from adult, wild‐caught and farmed seabass (Lates calcarifer) intestines for evaluation as possible probiotics using the well agar diffusion method. Five LAB isolates (designated as LAB‐1–5) were found to inhibit Aeromonas hydrophila, a known seabass pathogen. Median lethal concentrations (LC₅₀) of A. hydrophila on juvenile seabass were measured in aquaria. Median lethal concentration values of 7.76, 7.47 and 7.26 log₁₀ CFU mL^?1 for 72, 96 and 120 h, respectively, were found. Juvenile seabass (0.6±0.2 g) were cultured in aquaria and fed individual LAB‐1–5 fortified feeds with 7 log₁₀ CFU g^?1 LAB. Seabass fed LAB‐4 fortified feed had significantly greater growth (P<0.05) than fish fed other feeds. Seabass fed LAB‐4 also had greater survival, but this was non‐significant (P<0.05). Challenge tests of LAB‐4 fed seabass with A. hydrophila at ～7 log₁₀CFU mL^?1 yielded significantly greater survival compared with control seabass (P<0.05). Aeromonas hydrophila infections in seabass were confirmed by observing disease manifestation and by immunohistochemistry techniques. LAB‐4 was preliminarily identified using lactic acid analysis, biochemical and physical characteristics. It was further identified using 16S rDNA sequencing. LAB‐4 was identified as Weissella confusa (identity of 99%). GenBank accession number for the 16S rDNA sequence for LAB‐4 was AB023241.     

Biopreservative effect of pediocin ACCEL on refrigerated seafood

To investigate the biopreservative effectiveness of pediocin ACCEL on refrigerated seafoods, fresh fish fillets were immersed in various concentrations of pediocin ACCEL and then stored at either 4° or 0°C. Samples treated with nisin were used as a positive control. The aerobic plate counts (APC) of samples with bacteriocins were <2.0 log₁₀cfu/g (log cfu/g) after 2 days storage at 0°C, except that with 1500 IU/mL of pediocin ACCEL. The APC of samples with nisin were >2.0 log cfu/g after 2 days storage, while those with pediocin ACCEL occurred after 1 day storage at 4°C. In refrigerated seafoods, pediocin ACCEL and nisin suppressed the growth of inoculated Listeria monocytogenes during 2- and 1-week storage at 4°C, respectively. Compared with nisin, the pediocin ACCEL was considered to be more effective on the suppression of L. monocytogenes growth in refrigerated seafoods during 2-week storage at 4°C.     

不同乳酸菌对发酵草鱼品质的影响

为探明不同乳酸菌对发酵草鱼微生物数量和理化性质的影响,进一步提高发酵鱼制品的品质,实验对草鱼背部肌肉经不同乳酸菌(植物乳杆菌、戊糖片球菌和副干酪乳杆菌)发酵后制品的微生物数量、pH、总酸、水分含量、白度、氨基酸态氮、硫代巴比妥酸和挥发性盐基氮等进行分析,探究不同乳酸菌在草鱼发酵过程中(0～15d)对其品质的影响.结果显...     

Effects of Ozonated Water Treatment on the Microbial Population,Quality, and Shelf Life of Shucked Oysters (Crassostrea plicatula)

An ozonated water treatment system was designed for the sanitation of shucked oysters (Crassostrea plicatula). The effects of ozone (O₃) on shelf life were examined under refrigerated conditions (4 ± 1°C). Microbiological, chemical, and color quality were also evaluated by determining total aerobic plate counts (APC), total volatile basic nitrogen (TVB-N), thiobarbituric acid (TBA), and L, a, and b values. Single and orthogonal experiment results showed that oysters treated with 9 mg/L of O₃ in aqueous solution (oyster: ozonated water = 1:6, w/v) for 10 min at 5°C significantly reduced the total APC by about 2-log—from 4.97 ± 0.11 to 2.93 ± 0.17 log CFU/g (p < 0.05). O₃ treatment did not cause significant changes in TVB-N, TBA, a, and b values, although L values were significantly affected. During refrigerated storage, O₃-treated samples expressed lower TVB-N, TBA, a, and b values and higher L values than control samples. The shelf life of O₃-treated samples was 20 to 25 days, while that for the controls was 5 to 10 days. The current study confirms that treatment with ozonated water can effectively prolong the shelf life and maintain the quality of oysters.     

Removal of particle-associated bacteria by prefiltration and ultraviolet irradiation

The combined effect of prefiltration and ultraviolet (UV) irradiation on the removal of bacteria associated with plankton fragments was investigated in an experimental flowthrough system. The system was supplied by sea water containing fragments of Artemia nauplii in the size range 10–240 μm diameter (mean = 66 μm), as determined by particle size analysis. By applying an UV dose of 10 mJ cm^–2, the number of colony-forming units (CFU) was reduced from 7.4 × 10⁵ per 100 mL to 2.0 × 10³ per 100 mL. Increasing the dose to 13 or 22 mJ- cm^–2 did not result in any further reduction, suggesting that bacteria associated with Artemia fragments were protected. This protection hypothesis was supported by improved overall bacterial removal efficiency by prefiltration. At the highest dose (22 mJ cm^–2), more than 5 log₁₀ units total reduction was obtained by prefiltration using 50-μm mesh sizes. The reductions relative to the unfiltered sample were 1.4, 2.4 and 3.0 log₁₀ units using mesh sizes of 355, 80 and 50 μm respectively. It is concluded that sea water for aquacultural purposes should be filtered to remove particles before UV disinfection, thereby improving the overall bacterial removal efficiency and reducing the risk of introducing UV-shielded bacteria.     

Microbiological Quality of Farmed Tropical Freshwater Prawn (Macrobrachium rosenbergii de Man)

ABSTRACT

The objective of this study was to determine the microbiological quality of farmed giant freshwater prawn (Macrobrachium rosenbergii) collected from four freshwater farms located in Kerala (India). Microbiological counts on whole, deheaded, and deheaded and deveined prawn as well as on head and intestine were determined. Average counts (log₁₀ cfu g^?1) on whole prawn were 6.9 (total mesophilic counts (TPC) at 37°C) and 4.1 (psychrotrophic count at 7°C). The results indicated that the aerobic counts were within the acceptable limit. The levels of enterococci and faecal coliforms in farmed M. rosenbergii were high. There was an increase in the numbers of enterococci and Staphylococcus aureus after deheading. The major groups of bacteria comprising the flora of M. rosenbergii were Aeromonadaceae, Enterobacteriaceae and Pseudomonas. Farmed M. rosenbergii carried pathogenic bacteria such as Enterococcus spp., S. aureus, Aeromonas hydrophila, A. veronii biovar sobria and Clostridium perfringens. The results of the study suggest adoption of good farming and post harvest practices to improve the microbiological quality of farmed freshwater prawn.     

The Impact of Diets Supplemented with Different Forms of Rosemary and BHA on Chemical,Microbial and Sensory Properties of Rainbow Trout Fillet

The objective of this study was to evaluate the effect of different forms and doses of rosemary on chemical, microbial, and sensory properties of rainbow trout fed nine different diets: control (C), 20 g.kg^?1 rosemary powder (20RP), 40 g.kg^?1 rosemary powder (40RP), 0.3 g.kg^?1 rosemary extract (0.3RE), 0.6 g.kg^?1 rosemary extract (0.6RE), 0.15 g.kg^?1 rosemary nanopowder (0.15RNP), 0.3 g.kg^?1 rosemary nanopowder (0.3RNP), 0.15 g.kg^?1 butylated hydroxyanisole (BHA) (0.15BHA), and 0.3 g.kg^?1 BHA (0.3BHA). After 8 weeks’ feeding, the fish fillets were sampled on the 1st, 4th, 8th, 12th, and 16th days and then stored on 4°C. Lower value of pH, peroxide value (PV), total volatile base nitrogen (TVB-N), free fatty acids (FFA), and thiobarbituric acid (TBA) were reported in fish fed with RP, RE, RNP, and BHA; among them, RNP groups had the lowest properties (p < 0.05). Furthermore, lower total viable aerobic bacterial counts (TVC) and psychotropic counts (PTC) were observed in the fillets of the fish fed with rosemary treatments, especially in RNP treatments (7.52–9.41 log₁₀ CFU.g^?1), along with a slower spoilage in terms of sensory factors (texture, color, odor, and overall) on the 16th day. Finally, use of natural antioxidant nanorosemary in the diet may positively affect fish fillet quality and delay post-mortem deterioration.     

Effect of Lactobacillus acidophilussupplementation on growth performances,digestive enzyme activities and gut histomorphology of striped catfish (Pangasianodon hypophthalmusSauvage, 1878) juveniles

The influence of dietary supplementation of Lactobacillus acidophilus, on growth performance, digestive enzyme activities, gut histomorphology and gut microflora were evaluated in juveniles striped catfish (Pangasianodon hypophthalmus). Five experimental diets were formulated by supplementing 0, 10³, 10⁵, 10⁷ and 10⁹ CFU/g L. acidophilus in fishmeal and casein‐based semi‐purified diet. Triplicate groups of striped catfish (21.69 ± 0.18 g) were stocked in 15 fiberglass tanks with stocking density of 25 individuals per tank and fed twice daily at 2.5% of the fish body weight for 12 weeks. Weight gain, specific growth rate, feed conversion ratio and the protein efficiency ratio were significantly higher in fish fed with 10⁵ and 10⁷CFU/g L. acidophilussupplemented diets compared with the other treatment groups. Compared with the control and fish fed low (10³ CFU/g) L. acidophilus supplementation, those fed with 10⁵ and 10⁷ CFU/g had significantly higher (p < 0.05) apparent protein digestibility. Inclusion of L. acidophilus at 10⁷ CFU/g diet significantly increased amylase, protease and lipase activities. Microscopic analysis showed that the villi length in both the anterior and posterior gut and microvilli length in the posterior gut increased significantly in fish fed L. acidophilus supplementation at 10⁵ and 10⁷ CFU/g of diet. The fish fed L. acidophilus supplemented diets significantly increased the total lactic acid bacteria counts in the gut of striped catfish compared with the control‐fed group. Based on gut histomorphology and growth performance, inclusion of L. acidophilus at 10⁵ CFU/g appears to have the most positive effect on striped catfish farming.     

Protective Effect of a Non-Bacteriocinogenic Lactococcus piscium CNCM I-4031 Strain Against Listeria monocytogenes in Sterilized Tropical Cooked Peeled Shrimp

The protective activity of a non-bacteriocinogenic Lactococcus piscium CNCM I-4031 strain against Listeria monocytogenes was investigated in tropical cooked peeled shrimp stored at 8°C in modified atmosphere packaging (50% N₂–50% CO₂). When inoculated alone (L. piscium 10⁷ CFU g^?1 and L. monocytogenes 10⁴ CFU g^?1), protective culture and target strain grew very well on shrimp reaching a maximum cell number of 10⁹ CFU g^?1 after 7 and 14 days, respectively. In the presence of L. piscium, growth of L. monocytogenes was totally prevented after 3 days of storage. The count was 3.4 log CFU g^?1 lower than in the control after 10 days and until the end of storage (31 days). Using the Seafood Spoilage and Safety Predictor Software (http://sssp.dtuaqua.dk), it was shown that pH decrease from 6.58 to 5.94 and lactic acid concentration of 89.65 mM measured in the co-inoculated batch did not fully explain the inhibition observed.     

Effects of dietary Lactobicillus plantarum on the growth,carcass quality,and immune response of African catfish (Clarias gariepinus) challenged with Salmonella typhi

An experiment was conducted to investigate the effects of Lactobacillus plantarum on the production of African catfish (Clarias gariepinus). Five experimental diets containing 0, 10³, 10⁵, 10⁷, and 10⁹ CFU of Lactobacillus plantarum g^?1 diet (T₁–T₅ treatments respectively) were fed to African catfish (Clarias gariepinus) (9.20 ± 0.1 g initial body mass), for 70 days. Results indicated significantly lower growth performance in the fish fed diet without probiotics and in those fed diet with the least probiotic level. Treatments with probiotics significantly improved the blood profile and carcass protein but significantly reduced the carcass fat (P < 0.05); these treatments also marginally improved the carcass minerals in comparison with the treatment without probiotic (P < 0.05). Challenging the fish fed the experimental diets with Salmonella typhi showed higher immunity of fish fed the probiotic diets than those fed the nonprobiotic diet. Duncan’s multiple range test showed that the best fish performance was observed with 10³ CFU g^?1 L. plantarum for very parameter measured. However, regression analyses showed the optimum level of the bacteria to be 10^4.13–10⁵ CFU g^?1