Bacteria In Shrimp Research Articles

Functional and mechanistic studies of a phytogenic formulation, Shrimp Best, in growth performance and vibriosis in whiteleg shrimp

Climate change and disease threaten shrimp farming. Here, we studied the beneficial properties of a phytogenic formulation, Shrimp Best (SB), in whiteleg shrimp. Functional studies showed that SB dose-dependently increased shrimp body weight and decreased feed conversion ratio. We found that SB protected against Vibrio parahaemolyticus as evidenced by survival rate, bacterial load, and hepatopancreatic pathology in shrimp. Finally, we explored the likely mechanism by which SB affects growth performance and vibriosis in shrimp. The 16S rRNA sequencing data showed that SB increased 6 probiotic genera and decreased 6 genera of pathogenic bacteria in shrimp. Among these, SB increased the proportion of Lactobacillus johnsonii and decreased that of V. parahaemolyticus in shrimp guts. To dissect the relationship among SB, Lactobacillus and Vibrio, we investigated the in vitro regulation of Lactobacillus and Vibrio by SB. SB at ≥ 0.25 μg/mL promoted L. johnsonii growth. Additionally, L. johnsonii and its supernatant could inhibit V. parahaemolyticus. Furthermore, SB could up-regulate five anti-Vibrio metabolites of L. johnsonii, which caused bacterial membrane destruction. In parallel, we identified 3 fatty acids as active compounds from SB. Overall, this work demonstrated that SB improved growth performance and vibriosis protection in shrimp via the regulation of gut microbiota.

Small immune effectors coordinate peptidoglycan-derived immunity to regulate intestinal bacteria in shrimp.

Small antibacterial effectors, including lysozymes, lectins, and antimicrobial peptides, are key regulators of intestinal immunity. However, whether there is coordination among them during regulation is an interesting, but largely unknown, issue. In the present study, we revealed that small effectors synergistically regulate peptidoglycan-derived intestinal immunity in the kuruma shrimp, Marsupenaeus japonicus. A C-type lysozyme (LysC) was screened as a responsive factor for the intestine-bacteria interaction. LysC functions to restrict intestinal bacteria, mainly by cleaving Photobacterium damselae peptidoglycan to generate muropeptides which are powerful stimulators that induce anti-lipopolysaccharides factor B1 (AlfB1), an effective bactericidal peptide. The muropeptides also induce a C-type lectin (Ctl24), which recognizes peptidoglycan and coats bacteria. By counteracting LysC-mediated muropeptide release and AlfB1's bactericidal activity, Ctl24 prevents the continuous elimination of intestinal bacteria. Therefore, this study demonstrates a mechanism by which small immune effectors coordinate to achieve intestinal homeostasis, and provides new insights into peptidoglycan-derived intestinal immunity in invertebrates.

Antimicrobial Resistant Bacteria in Shrimp and Shrimp Farms of Bangladesh

The purpose of this study was to investigate the presence of pathogenic bacteria, specifically Escherichia coli and Salmonella and Vibrio species, and their antimicrobial resistance in shrimp aquaculture facilities of Bagerhat (Bangladesh). Sediment samples were collected from both Penaeus monodon and Macrobrachium rosenbergii farms and shrimp samples from the Macrobrachium rosenbergii facility. The abovementioned bacteria were not found, but five Enterobacterales (Proteus penneri, Proteus alimentorum, Morganella morganii, Enterobacter hormaechei subsp. xiangfangensis and Plesiomonas shigelloides) were detected. This is the first documented case of Enterobacter hormaechei subsp. xiangfangensis in a shrimp farm. Nine antibiotics—ampicillin, gentamicin, chloramphenicol, oxytetracycline, nitrofurantoin, levofloxacin, ciprofloxacin, azithromycin, and co-trimoxazole—were selected for antibiotic resistance testing, and the majority (88.9%) had at least one isolate that was resistant. Across sources, 78.0% of isolates were resistant to at least one antimicrobial, and multidrug resistance was also detected in 29.3% of all isolates. Despite the low number of samples analyzed, nine in total, the results of this experiment emphasize that shrimp farms in Bagerhat may have a problem with antimicrobial-resistant bacteria. This could have negative impacts on shrimp quality and consumers’ health.

Effects of soluble Antarctic krill protein-curcumin complex combined with photodynamic inactivation on the storage quality of shrimp

A new protein complex (SAKP-Cur) was successfully prepared by combining soluble Antarctic krill protein with curcumin through hydrophobic action. The potency of photodynamic inactivation (PDI) mediated by the complex on preserving the storage quality of shrimp at 4 °C was investigated by microbiological, chemical, physical and histological methods. Results showed that the SAKP-Cur significantly improved the stability of curcumin, and greatly inactivated the native bacteria in shrimp driven by PDI. Meanwhile, the complex-mediated PDI effectively reduced the endogenous enzyme activity, the production of total volatile basic nitrogen (TVB-N) and malondialdehyde (MDA) in shrimp. Moreover, it obviously maintained the integrity and elasticity of the muscle fibers, thereby reducing the loss of water in myofibrils. Notably, the SAKP-Cur enhanced the PDI potency to preserve the freshness of shrimp during 4 °C storage or freeze–thaw cycles treatment. Therefore, the SAKP-Cur coupled with PDI is an effective fresh-keeping technology for aquatic products.

Lysyl Oxidase-like Protein Recognizes Viral Envelope Proteins and Bacterial Polysaccharides against Pathogen Infection via Induction of Expression of Antimicrobial Peptides.

Lysyl oxidases (LOXs) are copper-dependent monoamine oxidases, and they play critical roles in extracellular matrix (ECM) remodeling. The LOX and LOX-like (LOXL) proteins also have a variety of biological functions, such as development and growth regulation, tumor suppression, and cellular senescence. However, the functions of LOXLs containing repeated scavenger receptor cysteine-rich (SRCR) domains in immunity are rarely reported. In this study, we characterized the antiviral and antibacterial functions of a lysyl oxidase-like (LOXL) protein containing tandem SRCR domains in Marsupenaeus japonicus. The mRNA level of LoxL was significantly upregulated in the hemocytes and intestines of shrimp challenged using white spot syndrome virus (WSSV) or bacteria. After the knockdown of LoxL via RNA interference, WSSV replication and bacterial loads were apparently increased, and the survival rate of the shrimp decreased significantly, suggesting that LOXL functions against pathogen infection in shrimp. Mechanistically, LOXL interacted with the envelope proteins of WSSV or with lipopolysaccharide and peptidoglycan from bacteria in shrimp challenged using WSSV or bacteria, and it promoted the expression of a battery of antimicrobial peptides (AMPs) via the induction of Dorsal nuclear translocation against viral and bacterial infection. Moreover, LOXL expression was also positively regulated by Dorsal in the shrimp challenged by pathogens. These results indicate that, by acting as a pattern recognition receptor, LOXL plays vital roles in antiviral and antibacterial innate immunity by enhancing the expression of AMPs in shrimp.

C-Type Lectin Maintains the Homeostasis of Intestinal Microbiota and Mediates Biofilm Formation by Intestinal Bacteria in Shrimp.

Intestinal microbiota are closely related to host physiology. Over the long course of evolution and interaction, both commensal bacteria and their host have evolved multiple strategies to adapt to each other. However, in invertebrates, the regulatory mechanism of intestinal microbiota homeostasis is largely unknown. In the current study, a digestive tract-specific C-type lectin, designated as CTL33, was identified because of its abundance and response to bacteria in the intestine of kuruma shrimp (Marsupenaeus japonicus). Silencing of CTL33 expression led directly to intestinal dysbiosis, tissue damage, and shrimp death. CTL33 could facilitate biofilm formation by the intestinal bacteria. This function originated from its unique architecture, with a lectin domain responsible for bacteria recognition and a coiled coil region that mediated CTL33 dimerization and cross-linked the bacteria into a biofilm-like complex. By mediating the formation of a biofilm, CTL33 promoted the establishment of intestinal bacteria in intestine and maintained the homeostasis of the microbiota. Thus, to our knowledge, we demonstrated a new mechanism of C-type lectin-mediated biofilm formation by intestinal bacteria, providing new insights into intestinal homeostasis regulation in invertebrates.

Vitamin D3 identified from metabolomic analysis of intestinal contents promotes an antibacterial response in shrimp intestinal immunity

Vibrio parahaemolyticus is a critical pathogenic bacterium for the kuruma shrimp, Marsupenaeus japonicus. Antibacterial drug application is the main method to control vibriosis in aquaculture; however, drug residues and the emergence of resistant bacteria have restricted their use. Therefore, the present study aimed to identify metabolites that are likely to play roles in the homeostasis of the intestinal microbiota, and to further explore their application in shrimp aquaculture. Metabolomic analysis, using high-performance liquid chromatography tandem mass spectrometry (HPLC/MS) of shrimp intestinal contents, was performed. The results showed that metabolic profiles changed distinctly in shrimp intestines after V. parahaemolyticus challenge compared with that in the control. The levels of 39 metabolites changed significantly after Vibrio challenge. Notably, vitamin D3 metabolism was enhanced in shrimp intestines after Vibrio challenge. Oral administration of 0.1 mg/kg vitamin D3 effectively improved the survival rate of shrimp infected with V. parahaemolyticus. Further studies indicated that vitamin D3 promoted bacterial clearance by regulating the expression of antimicrobial peptides genes in the shrimp intestines. Transcriptomics analysis revealed that vitamin D3 functioned in shrimp intestinal immunity by activating the prophenoloxidase system and Toll signaling pathway to induce the expression of certain antimicrobial peptides to maintain microbial homeostasis. Collectively, we identified vitamin D3 as an immunomodulatory factor that plays an important role in boosting the immune response against pathogenic bacteria in shrimp.

Identification and characterization of a novel mannose-binding C-type lectin (PjLec2) in shrimp Penaeus japonicus

C-type lectins (CTLs) are important molecules involved in the innate immunity of invertebrates. In this investigation, we reported a novel CTL (designated as PjLec2) from the marine shrimp Penaeus japonicus (P. japonicus). The cDNA of PjLec2 is 669 bp in length with an open reading frame (ORF) of 477 bp. It encodes a protein of 159 amino acids (aa) containing a putative 18-aa signal peptide and a carbohydrate recognition domain (CRD). The CRD of PjLec2 possesses an EPN (Glu-Pro-Asn) motif which is putatively responsible for mannose recognition. Expression pattern analysis demonstrated that PjLec2 mRNA is exclusively expressed in hepatopancreas in P. japonicus. At protein level, PjLec2 is detected in hemolymph and hepatopancreas. Recombinant PjLec2 has a mannose binding activity and a strong agglutination activity against Gram-negative bacteria Vibrio alginolyticus (V. alginolyticus) and Aromonas hydrophila (A. hydrophila) in a calcium-dependent manner. In addition, the expression of PjLec2 is significantly upregulated at both mRNA and protein levels after challenging shrimp with A. hydrophila. Our results indicated that PjLec2 may play a fundamental role in the recognition of pathogenic bacteria in shrimp.

Acyl-homoserine-lactones receptor LuxR of Shewanella baltica involved in the development of microbiota and spoilage of refrigerated shrimp.

Numerous bacterial species utilize quorum sensing molecules acyl-homoserine-lactones (AHLs) to communicate, however, crosstalk often complicates the dynamics and behaviors of mixed populations. In this study, we developed a luxR mutant of wild type Shewanella baltica SA03 (WT SA03), and aimed to investigate the role of S. baltica LuxR (AHLs receptor) involved in the spoilage of refrigerated shrimp (Litopenaeus vannamei) by inoculating WT SA03 and luxR mutant of S. baltica SA03 (ΔluxR SA03), respectively. The results indicated the maximum growth rate of total viable bacteria in shrimp inoculated with ΔluxR SA03 was 73.34% lower than that of WT SA03. The lag time of total bacteria in shrimp treated with ΔluxR SA03 were 87.6h, significantly longer than that of WT SA03. Meanwhile, the total volatile basic nitrogen concentrations of shrimp treated with WT SA03 were significantly higher than that of ΔluxR SA03 after 2days of storage, which were in agreement with the decrease of the content of AHLs of the shrimp. The results indicated S. baltica might utilize AHLs produced by other bacteria and accelerate the shrimp spoilage process through LuxR receptor system.

Biochemical and PCR Assay for Detection of Pathogenic Bacteria at Shrimp and Shrimp Farms in Bangladesh

The study was conducted to detect faecal coliforms and pathogenic bacteria in shrimp and shrimp farms. Although coliforms are widely distributed in the environment, but only a small percentage are pathogenic to humans. The presence of pathogenic bacteria in shrimp causes several waterborne infections in humans that are worldwide concerning issues. In order to better determination of the health risks that are associated with the exposure to pathogenic bacteria, a multiplex PCR system was used for the rapid detection of pathogenic Aeromonas sp., Clostradium sp., Listeria sp., Salmonella sp., Shigella sp., Vibrio sp. and Staphylococcus sp. in the water, sediment and shrimp. The target genes were chosen for this investigation included: Aer gene for Aeromonas sp., hilA gene for Salmonella sp., virA gene for Vibrio sp., Sec gene for Staphylococcus aureus, neurotoxin gene type A, B, E, F for Clostridium botulinum, internalin gene for Listera sp. andipaH gene for Shigella sp. Seven pairs of specific primers were used to amplify internal fragments of these genes by PCR to generate PCR products that could be analyzed and confirmed with relative ease by gel electrophoresis. The presence of Aeromona and Vibrio sp. were found in the water, sediment as well as in the shrimp that were dominant among other bacteria species. On the other hand, Salmonella and Clostridium group was found in the sediment of one sample but there is no evidence of Listeria, Staphylococcus and Shigella group in the farms. All of the samples contained relatively large number (1100 to ≥2400 cfu/g) of coliform bacteria. The unhygienic condition and polluted water source could be the major reasons for the occurrence of these types of pathogenic bacteria in the shrimp farms in this area. The result revealed that the PCRbased rapid detection system described in this study is a powerful method for routine monitoring and risk assessment of water quality in the shrimp farms and could be an effective tool for disease studies in our shrimp sector.

Impact of the O2 Concentrations on Bacterial Communities and Quality of Modified Atmosphere Packaged Pacific White Shrimp (Litopenaeus Vannamei)

The importance of spoilage-related bacteria in fresh Pacific white shrimp (Litopenaeus vannamei) under different modified atmospheres (MAs) at 4 °C and the effect of O2 were demonstrated in the current study. The changes of bacterial communities in MA-packed shrimp during cold storage were studied by a combined method of plate counts with isolation and identification. Three gas mixtures were applied: 80% CO2 /5% O2 /15% N2, 80% CO2 /10% O2 /10% N2 and 80% CO2 /20% O2, and unsealed packages of shrimp were used as the control. In addition, the TVB-N, pH, whiteness index, and sensory scores were also determined to evaluate the quality changes of shrimp. MA packaging effectively inhibited the increase of total psychrotrophic bacteria counts and H2 S-producing bacteria counts by about 1.7 and 2.1 log cycles, respectively. The growth of Gram-negative spoilage bacteria in shrimp, including Shewanella spp., Aeromonas spp., and Pseudomonas spp., was inhibited by MA packaging, but the growth rate of Gram-positive bacteria such as lactic acid bacteria (LAB) and Brochothrix spp. were less affected by MA as effectively as Gram-negative bacteria. In comparison with the MA-packaged samples, the counts of H2 S producers in shrimp under a CO2 -enriched atmosphere with 20% O2 were slightly lower than the count in samples under an atmosphere with 5% O2 . However, MA with 20% O2 led to higher concentrations of TVB-N, and lower whiteness values and sensory scores. The shelf life of shrimp under 80% CO2 /10% O2 /10% N2 has been prolonged by > 6 d in comparison with the control according to the sensory scores.

Potential Bacillus probiotics enhance bacterial numbers, water quality and growth during early development of white shrimp (Litopenaeus vannamei)

Epidemics of epizootics and occurrence of multiresistant antibiotics of pathogenic bacteria in aquaculture have put forward a development of effective probiotics for the sustainable culture. This study examined the effectiveness of forms of mixed Bacillus probiotics (probiotic A and probiotic B) and mode of probiotic administration on growth, bacterial numbers and water quality during rearing of white shrimp (Litopenaeus vannamei) in two separated experiments: (1) larval stages and (2) postlarval (PL) stages. Forms of Bacillus probiotics and modes of probiotic administration did not affect growth and survival of larval to PL shrimp. The compositions of Bacillus species in probiotic A and probiotic B did not affect growth and survival of larvae. However, postlarvae treated with probiotic B exhibited higher (P<0.05) growth than probiotic A and controls, indicating Bacillus probiotic composition affects the growth of PL shrimp. Total heterotrophic bacteria and Bacillus numbers in larval and PL shrimp or culture water of the treated groups were higher (P<0.05) than in controls. Levels of pH, ammonia and nitrite of the treated shrimp were significantly decreased, compared to the controls. Microencapsulated Bacillus probiotic was effective for rearing of PL L. vannamei. This investigation showed that administration of mixed Bacillus probiotics significantly improved growth and survival of PL shrimp, increased beneficial bacteria in shrimp and culture water and enhanced water quality for the levels of pH, ammonia and nitrite of culture water.

Salmonella and the Sanitary Quality of Aquacultured Shrimp

In this study, we examined the prevalence of Salmonella and coliform bacteria on shrimp aquaculture farms to develop guidelines or preventative measures for reducing Salmonella and fecal contamination on products harvested from these farms. The U.S. Food and Drug Administration, in conjunction with foreign government regulatory agencies, the aquaculture industry, and academia affiliates, analyzed 1,234 samples from 103 shrimp aquaculture farms representing six countries between July 2001 and June 2003 for fecal coliforms, Escherichia coli, and Salmonella. A significant relationship was found (P = 0.0342) between the log number of fecal bacteria and the probability that any given sample would contain Salmonella. The likelihood of any given sample containing Salmonella was increased by 1.2 times with each 10-fold increase in either fecal coliform or E. coli concentration. The statistical relationship between Salmonella concentration and that of both fecal coliforms and E. coli was highest in grow-out pond water (P = 0.0042 for fecal coliforms and P = 0.0021 for E. coli). The likelihood of finding Salmonella in grow-out pond water increased 2.7 times with each log unit increase in fecal coliform concentration and 3.0 times with each log unit increase in E. coli concentration. Salmonella is not part of the natural flora of the shrimp culture environment nor is it inherently present in shrimp grow-out ponds. The occurrence of Salmonella bacteria in shrimp from aquaculture operations is related to the concentration of fecal bacteria in the source and grow-out pond water.

Effect of Epinephelus coioides, Chanos chanos, and GIFT tilapia in polyculture with Penaeus monodon on the growth of the luminous bacteria Vibrio harveyi

Studies have shown that the presence of Tilapia hornorum hybrid has antibacterial effect against luminous bacteria. The present study aims to determine the effect of different fish species such as grouper, milkfish and tilapia in polyculture with shrimp on the growth of luminous bacteria. Results showed that stocking of tilapia Oreochromis niloticus hybrid and grouper Epinephelus coioides at a biomass of 500 g/m 3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass = 80 g/m 3) rearing water and positively affected shrimp survival. Results also showed that the presence of milkfish Chanos chanos at a biomass of 500 g/m 3 did not inhibit the growth of luminous bacteria in shrimp (biomass = 80 g/m 3) rearing water.

Efficiency of Chlorella sp. and Tilapia hornorum in controlling the growth of luminous bacteria in a simulated shrimp culture environment

This study clarifies the effect of green water from Chlorella sp., Tilapia hornorum and the combination of the two organisms on the growth of luminous bacteria in a simulated shrimp culture environment. Results showed that the presence of Chlorella sp. (10 5 cells/ml) alone was not effective in the control of luminous bacteria in shrimp (biomass=80 g/m 3) rearing water. The presence of T. hornorum alone (biomass=500 g/m 3) was more efficient in controlling the growth of luminous bacteria than the co-existence of tilapia and Chlorella sp. Nevertheless, the presumptive Vibrio count was lowest in control tanks that had the highest shrimp survival rate, which was attributed to the presence of other micro-algae such as Chaetoceros, Thalassiosira, Navicula, Nitszchia, Melosira, and Fragilaria.

Antibacterial activity of tilapia Tilapia hornorum against Vibrio harveyi

Disease due to luminous Vibrio has been a major problem of the shrimp industry. Different technologies have been introduced to control the disease. One of the techniques reported to work against luminous bacteria in the Philippines is the green water culture system (or finfish–shrimp integrated culture system). A green water culture system is an innovative technique wherein shrimp are cultured in water collected from a pond where tilapia or other fish species are grown. In some cases, the fish are cultured in an isolated net pen inside the shrimp culture pond. This study clarifies the effect of one component of the green water culture system, the presence of all male tilapia ( Tilapia hornorum) on luminous bacteria Vibrio harveyi. Results showed that stocking tilapia at a biomass not lower than 300 g/m 3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass=80 g/m 3) rearing water without the growth of microalgae.

The annual and semiannual variation of sea surface temperature in the North Pacific Ocean : Wyrtki Klaus, 1965. Limnol. Oceanogr., 10 (3): 307–313.

Epidemics of epizootics and occurrence of multiresistant antibiotics of pathogenic bacteria in aquaculture have put forward a development of effective probiotics for the sustainable culture. This study examined the effectiveness of forms of mixed Bacillus probiotics (probiotic A and probiotic B) and mode of probiotic administration on growth, bacterial numbers and water quality during rearing of white shrimp (Litopenaeus vannamei) in two separated experiments: (1) larval stages and (2) postlarval (PL) stages. Forms of Bacillus probiotics and modes of probiotic administration did not affect growth and survival of larval to PL shrimp. The compositions of Bacillus species in probiotic A and probiotic B did not affect growth and survival of larvae. However, postlarvae treated with probiotic B exhibited higher (P < 0.05) growth than probiotic A and controls, indicating Bacillus probiotic composition affects the growth of PL shrimp. Total heterotrophic bacteria and Bacillus numbers in larval and PL shrimp or culture water of the treated groups were higher (P < 0.05) than in controls. Levels of pH, ammonia and nitrite of the treated shrimp were significantly decreased, compared to the controls. Microencapsulated Bacillus probiotic was effective for rearing of PL L. vannamei. This investigation showed that administration of mixed Bacillus probiotics significantly improved growth and survival of PL shrimp, increased beneficial bacteria in shrimp and culture water and enhanced water quality for the levels of pH, ammonia and nitrite of culture water.