Growth Of Aeromonas Research Articles

Bacillus subtilis and xylo-oligosaccharide ameliorates NaHCO3-induced intestinal barrier dysfunction and autophagy by regulating intestinal microflora and PI3K/Akt pathway of crucian carp (Carassius auratus)

This study was to demonstrate that the alleviate effect of synbiotics (Bacillus subtilis and xylo-oligosaccharide) on NaHCO3-induced intestinal barrier dysfunction and autophagy of crucian carp (Carassius auratus). In a 2×2 factorial design, crucian carp were divided into 4 groups, fed with diets contained two levels of synbiotics (0 and 1× 108 CFU/g) and treated with two levels of NaHCO3 (0 and 50 mmol/L) for 56 days. The results showed that NaHCO3 and synbiotics significantly affected intestinal fold height, permeability, the mRNA expression of tight junction, antioxidant capacity, immunity function (except LZM), inflammation response, the mRNA and protein expression of autophagy (except Beclin1 protein) and PI3K/Akt pathway (P<0.05). Intestinal muscular layer thickness, the levels of LZM and the protein expression of Beclin1 only affected by NaHCO3 (P<0.05). In addition, the interaction between NaHCO3 and synbiotics was observed for intestinal fold height, the mRNA expression of Claudin 4, Nrf2, Keap1, HO-1, SOD, GPX4a, GPX4b, TNF-α, IL-6, PI3K, ATG5 and ATG7, the levels of ROS and ACP, the protein expression of p-PI3K/PI3K, p-Akt/Akt, ATG5, ATG7, Beclin1 and LC3Ⅱ/LC3Ⅰ (P<0.05). Additionally, this study highlights that the synbiotics facilitated the colonisation Bacillus and Cetobacterium, while concurrently inhibited the growth of Aeromonas in intestines. These findings suggested that dietary synbiotics (Bacillus subtilis and xylo-oligosaccharide) can effectively alleviated NaHCO3-induced intestinal dysfunction oxidative stress and autophagy by regulating intestinal microflora and PI3K/Akt pathway.

THE ANTIBACTERIAL POTENTIAL OF EUKARYOTIC MARINE MICROALGAE AGAINST PATHOGENS FROM CHICKEN, DOG AND AQUACULTURE

Antibiotic resistance is an emerging concern, leading to the search for alternative antibacterial agents. Scientists looking for potential alternatives to antibiotics see promise in the antimicrobial propensity of microalgae. We investigated the antibacterial potentials of Tetraselmis, Chlorella, and Nannochloropsis against pathogenic bacteria from chicken, dogs, and fish. We identified E. coli, Stenotrophomonas sp., Streptococcus sp., Staphylococcus sp., Aeromonas sp. and Lysinibacillus sp. by colony characteristics, Gram staining and VITEK-2 tests. Results demonstrated that Tetraselmis was highly sensitive against Stenotrophomonas sp. (p &lt; 0.0001) and E. coli (p &lt; 0.001) from chicken, and Staphylococcus sp. (p &lt; 0.01) from dogs. Moreover, Chlorella was highly sensitive against E. coli (p &lt; 0.0001) from dogs. All the bacteria isolated from chicken were moderate to highly sensitive to Chlorella. Nannochloropsis was marginally sensitive to all the bacteria isolated from chickens and dogs. The minimum inhibitory concentration values indicate that a minimum of 10 mg/ml of Tetraselmis can suppress the growth of Aeromonas sp. from fish and Chlorella can suppress E. coli and Stenotrophomonas sp. from chicken. Results indicate that native microalgae may have an active somatic or secretory components that prevent bacterial cell division and/or induce lysis. Advanced studies should be performed to identify the active component for the development of newer and sustainable antimicrobial drugs.

AEROMONAS IMMUNE MODULATOR PROTEINS INTERACT WITH HOST LIPOCALIN-2 TO MEDIATE INFLAMMATION THROUGH BOTH HOST- AND MICROBIOME-SPECIFIC MECHANISMS

Abstract Inflammatory bowel diseases (IBD) are a prevalent and growing clinical health problem worldwide. The etiology of IBD involves complicated interactions between immunological genetic variants, environmental factors, and the intestinal microbiome. Current therapies for IBD include corticosteroids and biologics, which can ameliorate overproduction of pro-inflammatory cytokines, and other inflammatory mediators, but which do not treat the microbiome dysbiosis that often triggers or propagates inflammation. Therefore, an urgent need exists for more effective therapies for IBD that treat both inflammation and microbiome dysbiosis. Health-associated microbes are under-explored sources of mechanisms that maintain tissue and immune homeostasis. Our research team at the University of Oregon has identified a novel family of anti-inflammatory proteins secreted by a zebrafish gut symbiont, Aeromonas, which we named Aeromonas immune modulator (Aim) proteins. Host Lipocalin-2 (LCN2) limits the growth of tissue-resident microbes through sequestration of iron, an essential micronutrient, by binding bacterial iron-laden siderophore molecules. Aim proteins allow the zebrafish symbiont Aeromonas to overcome this LCN2-mediated iron starvation. Structurally, Aim proteins contain lipocalin folds and we discovered that Aims and LCN2 physically interact, suggesting that Aim proteins allow Aeromonas to recapture siderophores sequestered by LCN2. In addition to supporting the growth of Aeromonas in the zebrafish intestine, Aim proteins decrease host tissue inflammation both in microbially-induced and injury models. In the context of infection with a zebrafish pathogenic Vibrio, Aim proteins decrease tissue inflammation while simultaneously increasing Vibrio growth, suggesting that Vibrio exploits Aim proteins to overcome nutritional immunity and down-regulate programs of tissue destruction. In addition to siderophores, LCN2 and other LCNs binds a wide array of hydrophobic molecules, including immunomodulatory lipid hormones such as prostaglandins. We hypothesize that Aim proteins exert their diverse effects on bacterial growth and tissue homeostasis through their binding to LCN2 and other LCNs. This work suggests a new molecular mechanisms through which resident microbes promote tissue homeostasis by counteracting nutritional immunity, alleviating bacterial tissue destruction, and dampening the action of pleotropic host immunomodulatory LCNs. Furthermore, Aim proteins have the potential to be developed as a novel therapeutic for IBD, unique in its ability to both target a primary mediator of inflammation, neutrophils, and facilitate restoration of microbiome dysbiosis.

Monitoring and prediction of Aeromonas veronii dynamics via absolute quantification microbiome sequencing facilitated the development of a risk assessment tool in a shrimp farm

The outbreak of infectious bacterial diseases in aquaculture is a major concern in the industry. Among those pathogens, Aeromonas species are one of the most important bacterial pathogens of cultured animals. From May to June of 2022, an unexplained Aeromonas veronii outbreak was observed in a shrimp farm with high morbidity and mortality. To develop a risk assessment tool, the dynamics of the microbiome were monitored via absolute quantification of 16S rRNA amplicon sequencing for 18 consecutive days in a recirculating aquaculture system (RAS) for rearing water and the gut of whiteleg shrimp (Litopenaeus vannamei). A growth model was also developed for predicting the growth of Aeromonas in the shrimp gut and rearing water. The results showed that A. veronii is a dominant bacterial strain isolated from sick L. vannamei. The comparison of the bacterial community in the shrimp gut and rearing water over time showed remarkable shifts in A. veronii and probiotic Bacillus in the rearing water, with a significant decline in probiotic Bacillus. The rapid increase in A. veronii in rearing water subsequently altered A. veronii populations in the shrimp gut, with over 80% of A. veronii found on day 18. Linear regression analysis revealed a strong positive relationship between the abundance of A. veronii in the shrimp gut and the rearing water. The growth kinetic model agreed well with the observed values. Collectively, the temporal dynamics of the bacterial community in the rearing water offer valuable information for the fate of administered probiotics and pathogens. Growth kinetic models provide useful information to reduce the abundance of pathogens, which can be used as an early warning tool. These observations offer crucial insights into the dynamics of the bacterial community in shrimp and their environment, which can significantly impact shrimp health and productivity.

Aeromonas nosocomial cluster: Investigation review of possible modes of transmission

Background:Aeromonas is a gram-negative rod known to be present in water, sewage and soil which may cause infections especially in immunocompromised hosts. Cases of Aeromonas gastroenteritis have been associated with warmer weather. In total, 3 patients with extensively drug resistant (XDR) Aeromonas were identified at our facility between August and September 2022 on 2 intensive care units (ICUs). Our infection prevention, microbiology, and facility teams investigated these cases to determine whether a common source could be the mode of transmission. Methods: To first determine whether patients’ Aeromonas specimens were related, whole-genome sequencing (WGS) of the clinical isolates from 3 patients was performed using the Illumina DNA Prep Kit and Illumina MiSeq. Sequencing analysis was performed using CLC Genomics Workbench for de novo assembly, single-nucleotide polymorphisms (SNP) calling, and tree generation, Geneious Prime for reference-based assembly, annotation, and quality assessment, KmerFinder for reference identification, and the Comprehensive Antibiotic Resistance Database for resistance gene detection via protein homology. Chart review revealed that patients occupied multiple rooms between 2 ICUs (Fig. 1). Because water is a known source of Aeromonas, facility records were reviewed for water intrusion events. This analysis identified several cases in the affected patient and surrounding rooms. Sinks and faucets from 10 rooms were swabbed followed by direct plating on blood, MacConkey agar, and Aeromonas-selective cefsulodin-Irgasan-novobiocin (CIN) agar plates. Lastly, the city temperatures before and after positive cases were reviewed to identify whether any correlation could be shown between temperature and timing of infection. Results: WGS analysis revealed that the 3 Aeromonas isolates (all identified as A. hydrophila) were not directly related (minimum distance, 934 SNPs) and harbored between 4 and 19 unique antimicrobial resistance genes, including co-occurring carbapenemases VIM-2 and KPC-3 in 1 isolate and OXA-232 in another. Of the 20 environmental samples, few gram-negative nonfermenting bacteria and no Aeromonas isolates were detected (Fig. 1). Elevated city did loosely proceed patient cases of Aeromonas, suggesting a possible role of higher temperature, which may have promoted the growth of Aeromonas during the periods of the 3 cases and thus may contribute to the nosocomial infections (Fig. 2). Conclusions: Although our investigation did not reveal a definitive cause for the Aeromonas cases, it did show the importance prompt identification and investigation can have on mitigating the spread of a cluster. Our facility has not identified any additional nosocomial cases. Monitoring water intrusion events and plans for remediation continue to be a priority.Disclosures: None

Effect of slightly acid electrolysed water ice on metabolite and volatilome profile of shrimp (Penaeus vannamei) during cold storage

Slightly acid electrolyzed water (SAEW) ice has been proven to be effective in preserving shrimp quality during storage in our previous study. The present study aimed to investigate the underlying mechanism of the preservative effect of SAEW ice on metabolic profiles and volatiles production in shrimp during cold storage. The results demonstrated that the SAEW ice retarded the growth of Aeromonas, H2S-producing bacteria, lactic acid bacteria, and Pseudomonas (−2.9, 2.0, 1.6, and 0.7 log CFU/g, respectively), exhibiting better antibacterial activity compared with tap water (TW) ice and NaCl ice. Besides, nuclear magnetic resonance (NMR)-based metabolome combined with volatilome analysis revealed that SAEW ice maintained the contents of umani- and sweetness-related amino acids. Meanwhile, the accumulation of undesirable spoilage-related markers was inhibited, including lactic acid, 2, 3-butanediol, HxR, histidine, ethanol, 2-ethyl-1-hexanol, 2-methyl-butanal, and 3-methyl-butanal (2–10 times reduction compared with the other two groups). This study collaboratively reveals the mechanism of controlling seafood quality by regulating spoilage metabolites through the use of SAEW ice.

The effect of food processing factors on the growth kinetics of Aeromonas strains isolated from ready-to-eat seafood

Aeromonas are ubiquitous aquatic bacteria and frequently isolated from seafood. There is growing awareness of Aeromonas as foodborne pathogens, particularly in connection with consumption of ready-to-eat (RTE) seafood. The aim of this study was to investigate the effect of food processing factors on the growth kinetics of eight Aeromonas strains (representing seven species) isolated from RTE seafood. The effect of low temperature (4 and 8 °C) in combination with different NaCl concentrations (0.5–6.5 %) or with two purified condensate smokes (PCSs; Red Arrow SmokEz VTABB and JJT01) at different concentrations (0–0.26 %) was studied in Trypton Soy Broth (TSB). In food processing, application of PCS is considered healthier than traditional smoking. Growth kinetics parameters of each strain were estimated by using a primary predictive model. Our result showed that the addition of 3.5 % NaCl at refrigeration temperature (4 °C) was not sufficient to inhibit the growth of A. media, A. bestiarum, A. piscicola, and A. salmonicida, while higher NaCl concentration (≥5.0 %) at 8 °C suppressed their growth. On the other hand, our result demonstrated the antimicrobial potential of using PCS at maximal allowed concentration (0.26 %) against Aeromonas. PCS concentration and phenol content were important factors influencing the growth kinetics parameters of Aeromonas. Moreover, the growth kinetics of three Aeromonas strains were further studied in commercially produced vacuum-packed fresh and cold-smoked salmon stored at 4 °C for 14 and 21 days, respectively. Our results demonstrate that vacuum packing combined with cold storage at 4 °C was insufficient to inhibit the growth of Aeromonas in fresh salmon, while the growth was inhibited in a minimally salted cold-smoked salmon (salt content of 1.8 %). Our study implies that mild food processing factors applied in the production of RTE seafood might not guarantee the total inhibition of Aeromonas. Even though further studies on evaluating the antimicrobial potential of PCSs in actual seafood matrixes are necessary, the present study suggests that PCS technology might be a promising approach to prevent the potential growth of Aeromonas.

Aeromonas species from non-chlorinated distribution systems and their competitive planktonic growth in drinking water.

Aeromonas is included in the Dutch Drinking Water Decree as an indicator for elevated microbial regrowth in non-chlorinated drinking water distribution systems (DWDS). The temporal and spatial diversity of Aeromonas species in ten DWDS and their planktonic growth characteristics for different carbon sources was investigated. Genotyping of the gyrB gene of isolates showed a non-systematic temporal and spatial variable prevalence of seven different Aeromonas species in these DWDS and no correlation with AOC-P17/NOX and Aeromonas concentrations. Pure cultures of these seven species showed a high affinity to low concentrations (μg/L) of individual amino acids and fatty acids, compounds associated with biomass. Growth occurred at 0.5 μg-C/L of an amino acid mixture. Growth of a mixed community of A. rivuli, A. salmonicida, A. sobria and A. veronii in drinking water occurred in pasteurized samples, however, no growth and decay occurred in competition with the autochthonous bacteria (non-pasteurized samples). This community also failed to grow in non-pasteurized distribution samples from a location with clear increase in planktonic Aeromonas concentrations in the transported drinking water. For competitive planktonic growth of Aeromonas an amino acid concentration of ≥5 μg-C/L is required. AOC-P17/NOX concentrations showed that such concentrations are not expected in Dutch drinking water. Therefore, we suspect that competitive planktonic growth is not the major cause of the observed non-compliance with the Aeromonas standard in non-chlorinated DWSD.Importance The occurrence of the bacterial genus Aeromonas in non-chlorinated drinking water in the Netherlands is regarded as an indication for elevated microbial regrowth in the distribution system. Identification of the prevalent species in ten distribution systems by genotyping yielded seven different species, with A. rivuli, A. veronii and A. sobria as the most dominant ones. Planktonic growth experiments of pure cultures confirmed former published affinity of Aeromonas for certain biomass compounds (amino and fatty acids). In competition with the autochthonous microflora, however, planktonic growth was not observed, only after addition of a threshold amino acid concentration of 5 μg-C/L. Based on our results and further observations we deduced that planktonic growth of Aeromonas in the DWDS is not very likely. Benthic growth in loose deposits and planktonic release is a more plausible explanation for the observed planktonic increase of Aeromonas.

Protein oxidation analysis based on comparative proteomic of Russian sturgeon (Acipenser gueldenstaedti) after sous-vide cooking

Russian sturgeon meat is a highly perishable food product due to the microbial spoilage. Sous-vide cooking (SVC) at 40 °C, 50 °C and 60 °C with short-term time was applied to sturgeon fillets for the extension of shelf-life and the effect was investigated during storage at 4 °C. Results showed that SVC at 60 °C could effectively inhibit the growth of Aeromonas and Pseudomonas in samples. However, lipid oxidation and protein oxidation and degradation were aggravated with the myosin light chain (MLC), myosin heavy chain (MHC) and sulfhydryl content reduced after the treatment. Proteomics indicated that differentially expressed proteins were mainly involved in cellular component (CC) and biological process (BP). In this experiment, SVC were useful to preserve meat products, and the problem of protein oxidation should be further explored.

Effect of grape seed extract on quality and microbiota community of container-cultured snakehead (Channa argus) fillets during chilled storage

Herein, the effects of grape seed extract (GSE) on the microflora and biochemical changes of container cultured snakehead (Channa argus) fillets during 11 days of chilled storage were investigated. The sensory analysis, the total number of viable colonies, the total amount of volatile basic nitrogen, and k-value analysis revealed that GSE retarded the deterioration of snakehead fillets. The degradation of inosine 5′-monophosphate and the accumulation of inosine and hypoxanthine in the GSE group were slower than these in the control group. Moreover, GSE treatment effectively decreased the accumulation of putrescine, cadaverine, and histamine. Illumina-MiSeq high throughput sequencing results showed that GSE inhibited the growth of Aeromonas on snakehead fillets. Based on the microbial enumeration, sensory analysis, and k-value, GSE prolonged the shelf life of fillets for 3 days, suggesting its potential for snakehead fillets preservation.

Distribution and Potential Effects of 17β-Estradiol (E2) on Aeromonas Diversity in Wastewater and Fish Samples.

Recently, there has been evidence for the accumulation of steroid hormones in the water environment with negative consequences on fish and humans. However, there is paucity of information on how the steroid hormones influence the microbial community in environmental waters. The objective of this study was to determine the occurrence of 17β-estradiol (E2) and its potential influence on the diversity of Aeromonas spp. Wastewater samples were obtained from sewage treatment plants in northern South Africa and fish samples were collected from the Nandoni dam. Aeromonas spp. were isolated using microbiological methods and PCR protocols were used for their identification. A commercial Elisa kit was used for measuring the concentration of 17β-estradiol (E2) from the wastewater samples as well as the fish samples. 17β-estradiol (E2) was found in high concentration in sewage samples varying from 0.32-348.6 pg mL-1 while in fish samples, it ranged from 1.1-73.6 pg mL-1. There was a tendency of samples with high E2 concentrations to have higher diversity of Aeromonas spp., implying that steroid hormones may serve as nutrient for Aeromonas spp. Aeromonas hydrophila was the most prevalent species (71%), followed by A. sobria with (68%). The presence of Aeromonas spp. in environmental waters and fish that is consumed by the local community poses a serious health concern. The high content of E2 in treated wastewater is of serious concern as well. For the first time, the present study showed a positive impact of E2 on Aeromonas growth.

Antibacterial effect of lactic acid bacteria against psychrotrophic microorganisms in fresh minced beef meat during storage at 4 celsius

Abstract This study was conducted to investigate the antimicrobial effect of probiotic (Lactobacillus casei, Lactobacillus dulbrueckii and Bifidobacterium lactis) against psychrotrophic bacteria; which gave a promising biopreservation technique against psychrotrophs, pseudomonas and aeromonas growth in raw fresh minced beef meat during refrigerated storage at 4OC for 10 days. The meat samples were divided into 4 portions (100 g. each), portion A was inoculated with lactobacillius casei, portion B was inoculated with lactobacillus delbrueckii, portion C was inoculated with Bividobacterium lactis and control group. Results showed the reduction in the mean psychrotrophic count, mean pseudomonas count and mean aeromonas count as followed 5.63x104, 2.30x104, and 2.57x103 CFUg for group A; 4.00x104, 1.20x104, and 1.60x103 CFUg for group B; 1.40x104, 7.20x103, and 6.40x102 CFUg for group C, respectively. As conclusion ,using of probiotics as bio-preservatives in fresh minced beef meat are of promising trend for its health benefits and antibacterial effect on total psychrotrophic count ,pseudomonas count and aeromonas count.

Increased algicidal activity of Aeromonas veronii in response to Microcystis aeruginosa: interspecies crosstalk and secondary metabolites synergism.

Toxic Microcystis spp. blooms constitute a serious threat to water quality worldwide. Aeromonas veronii was isolated from Microcystis sp. colonies collected in Lake Kinneret. Spent Aeromonas media inhibits the growth of Microcystis aeruginosa MGK isolated from Lake Kinneret. The inhibition was much stronger when Aeromonas growth medium contained spent media from MGK suggesting that Aeromonas recognized its presence and produced secondary metabolites that inhibit Microcystis growth. Fractionations of the crude extract and analyses of the active fractions identified several secondary metabolites including lumichrome in Aeromonas media. Application of lumichrome at concentrations as low as 4 nM severely inhibited Microcystis growth. Inactivation of aviH in the lumichrome biosynthetic pathway altered the lumichrome level in Aeromonas and the extent of MGK growth inhibition. Conversely, the initial lag in Aeromonas growth was significantly longer when provided with Microcystis spent media but Aeromonas was able to resume normal growth. The longer was pre-exposure to Microcystis spent media the shorter was the lag phase in Aeromonas growth indicating the presence of, and acclimation to, secondary MGK metabolite(s) the nature of which was not revealed. Our study may help to control toxic Microcystis blooms taking advantage of chemical languages used in the interspecies communication.

Application of Illumina-MiSeq high throughput sequencing and culture-dependent techniques for the identification of microbiota of silver carp (Hypophthalmichthys molitrix) treated by tea polyphenols

This study evaluated the antimicrobial effects of tea polyphenols (TP) on changes in microbiota composition and quality attributes in silver carp fillets stored at 4 °C. During storage, TP treatment was found to be effective in enhancing sensory quality, inhibiting microbial growth, and attenuating chemical quality deterioration. Meanwhile, the composition of microbiota of silver carp fillets was investigated using culture-dependent and culture-independent methods. Initially, compared to the control, TP obviously decreased the relative abundance of Aeromonas, which allowed Acinetobacter and Methylobacterium to become the dominant microbiota in TP treated fillets on day 0. The controls, 0.5% TP-treated fillets, and 1% TP-treated fillets were rejected by sensory panelists on days 8, 12, and 12, respectively. At the time of sensory rejection, Aeromonas, followed by Acinetobacter and Pseudomonas, became the main spoilers in the control on day 8. However, TP treatment inhibited the growth of Aeromonas and Acinetobacter significantly. Consequently, Aeromonas followed by Pseudomonas and Shewanella became the predominant microbiota in all TP-treated fillets on day 12. Therefore, TP improved the quality of fillets during chilled storage, which was mainly due to their modulating effects on microbiota that resulted in the change in pattern and process of spoilage in fillets.

The effect of essential oils on microbial composition and quality of grass carp (Ctenopharyngodon idellus) fillets during chilled storage

Antimicrobial and antioxidant effects of essential oils (oregano, thyme, and star anise) on microbial composition and quality of grass carp fillets were investigated. Essential oils treatment was found to be effective in inhibiting microbial growth, delaying lipid oxidation, and retarding the increase of TVB-N, putrescine, hypoxanthine, and K-value. Based on sensory analysis, shelf-life of grass carp fillets was 6days for control and 8days for treatment groups. Among the essential oils, oregano essential oil exhibited the highest antimicrobial and antioxidant activities. GC-MS analysis of essential oils components revealed that carvacrol (88.64%) was the major component of oregano essential oil. According to the results of high-throughput sequencing, Aeromonas, Glutamicibacter, and Aequorivita were the predominant microbiota in fresh control samples. However, oregano essential oil decreased the relative abundance of Aeromonas, while thyme and star anise essential oils decreased the relative abundance of Glutamicibacter and Aequorivita in fresh treated samples. The microbial composition of both control and treatment groups became less diverse as storage time increased. Aeromonas and Pseudomonas were dominant in spoiled samples and contributed to fish spoilage. Compared to the control, essential oils effectively inhibited the growth of Aeromonas and Shewanella in grass carp fillets during chilled storage.

Evaluation of water quality during successive severe drought years within Microcystis blooms using fish embryo toxicity tests for the San Francisco Estuary, California

In the San Francisco Estuary, California, the largest estuary on the Pacific Coast of North America, the frequency and intensity of drought and associated cyanobacteria blooms are predicted to increase with climate change. To assess the impact of water quality conditions on estuarine fish health during successive severe drought years with Microcystis blooms, we performed fish embryo toxicity testing with Delta Smelt and Medaka. Fish embryos were exposed to filtered ambient water collected from the San Francisco Estuary during the Microcystis bloom season in 2014 and 2015, the third and fourth most severe recorded drought years in California. Medaka embryos incubated in filtered ambient waters exhibited high mortality rates (>77%), which was mainly due to bacterial growth. Medaka mortality data was negatively correlated with chloride, and positively correlated with water temperature, total and dissolved organic carbon, and ambient and net chlorophyll a concentration. Delta Smelt embryo mortality rates were lower (<42%) and no prominent seasonal or geographic trend was observed. There was no significant correlation between the Delta Smelt mortality data and water quality parameters. Aeromonas was the dominant bacteria that adversely affected Medaka. The growth of Aeromonas was suppressed when salinity was greater than or equal to 1psu and resulted in a significant reduction in mortality rate. Bacterial growth test demonstrated that the lysate of Microcystis cells enhanced the growth of Aeromonas. Toxin production by Microcystis is a major environmental concern, however, we conclude that dissolved substances released from Microcystis blooms could result in water quality deterioration by promoting growth of bacteria. Furthermore, a distinctive developmental deformity was observed in Medaka during the toxicity tests; somite formation was inhibited at the same time that cardiogenesis occurred and the functional heart was observed to be beating. The exact cause of the embryonic developmental deformity is still unknown.

Antimicrobial effects of cinnamon bark oil on microbial composition and quality of grass carp (Ctenopharyngodon idellus) fillets during chilled storage

In this study, 11 essential oils were initially screened for antimicrobial activity against Aeromonas veronii, Acinetobacter johnsonii, Shewanella putrefaciens, and Pseudomonas jessenii. Cinnamon bark oil exhibited the highest antimicrobial activity and was used as a natural preservative in grass carp fillets stored at 4 ± 1 °C. Sensory assessment, total volatile basic nitrogen (TVB-N), color, biogenic amines, adenosine triphosphate (ATP)-related compounds, K-value, and presence of microbiota were analyzed during storage. Cinnamon bark oil treatment was found to be effective in enhancing organoleptic quality, inhibiting microbial growth, and delaying the increase of TVB-N, putrescine, cadaverine and K-value. Based on sensory analysis, shelf-life of grass carp fillets was 8 days for the control and 12 days for the treatment group. According to high-throughput sequencing, Aeromonas and Pseudomonas were the predominant microbiota in fresh grass carp. As storage time progressed, the microbial composition of both control and treatment samples became less diverse. Pseudomonas followed by Aeromonas were dominant in spoiled control samples. However, there were significant differences in microbial composition between control and treatment samples at the end of storage. Cinnamon bark oil treatment inhibited the growth of Aeromonas and Shewanella, and Pseudomonas was the only predominant microbiota found in spoiled treatment samples.

The juicy sarcotesta of Punica granatum contains a lectin that affects growth, survival as well as adherence and invasive capacities of human pathogenic bacteria

Pomegranate (Punica granatum L.) fruits are referred as a “superfood” due to its immense potential for health benefits. This work describes the isolation, characterization and antibacterial effects of P. granatum sarcotesta lectin (PgTeL), a 26-kDa chitin-binding protein with 37% homology with a chitinase from pomegranate seeds. PgTeL was bacteriostatic and bactericide agent on Micrococcus luteus, Serratia marcescens and Streptococcus mutans (MIC50: 1.25–50 µg/mL; MBC: 18.0–100 µg/mL) and also inhibited the growth of Aeromonas sp., Enterococcus faecalis, Escherichia coli, Klebsiella sp., Salmonella enterica serovar. Enteritidis, Staphylococcus aureus, Staphylococcus epidermidis and Staphylococcus saprophyticus (MIC50: 3.0–50 µg/mL). The adhesion and invasion abilities of Aeromonas sp., S. aureus, S. marcescens and S. enterica to HeLa cells were reduced when these bacteria were previously treated with PgTeL. In conclusion, the pomegranate juicy sarcotesta is a source of a lectin with biotechnological potential as a new antibiotic agent.

Effect of cinnamon essential oil on bacterial diversity and shelf-life in vacuum-packaged common carp (Cyprinus carpio) during refrigerated storage

The present study investigated the effect of cinnamon essential oil on the quality of vacuum-packaged common carp (Cyprinus carpio) fillets stored at 4±1°C in terms of sensory scores, physicochemical characteristics (total volatile basic nitrogen (TVB-N), biogenic amines, and color), and presence of spoilage microbiota. A total of 290,753 bacterial sequences and 162 different genera belonging to 14 phyla were observed by a high-throughput sequencing technique targeting the V3–V4 region of 16S rDNA, which showed a more comprehensive estimate of microbial diversity in carp samples compared with microbial enumeration. Before storage, Macrococcus and Aeromonas were the prevalent populations in the control samples, but cinnamon essential oil decreased the relative abundance of Macrococcus in the treated samples. Variability in the predominant microbiota in different samples during chilled storage was observed. Aeromonas followed by Lactococcus were the major contaminants in the spoiled control samples. Microbial enumeration also observed relatively higher counts of Aeromonas than other spoilage microorganisms. Compared with the control samples, cinnamon essential oil inhibited the growth of Aeromonas and Lactococcus were the predominant components in the treated samples on day 10; plate counts also revealed a relatively high level of lactic acid bacteria during refrigerated storage. However, there were no significant differences (P>0.05) in the composition of dominant microbiota between these two treatments at the end of the shelf-life. Furthermore, cinnamon essential oil treatment was more effective in inhibiting the increase of TVB-N and the accumulation of biogenic amines (especially for putrescine and cadaverine levels). Based primarily on sensory analysis, the use of cinnamon essential oil extended the shelf-life of vacuum-packaged common carp fillets by about 2days.

Potential of Patikan Kerbau (Euphorbia hirta) as Antibacterial on Aeromonas hydropilla and Vibrio alginolitycus in Fish Culture

The aims of this study were to find out the potential of Patikan kerbau (Euphorbia hirta ) as antibacterial on Aeromonas hydropilla and Vibrio alginolyticus . Phytochemical study on E. hirta leaves was carried out to determine the chemical compounds group and resulted in the presence of phenolic, terpenoid and tannin group in the leaves. The antibacterial assay by diffusion agar using paper disc showed that methanol and aqueou extract either of using dried powder leaves boiling method or fresh leaves boiling method were able to inhibit the growth of Aeromonas. hydropilla and Vibrio alginolyticus . The highest antibacterial activity against those bacteria was shown by methanol extract. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of this methanol extract was found to be 0.156 and 0.625 % by using agar dilution method. In addition, the toxicity study exhibited that treatment of cat fish ( Clarias batrachus ) larvae and humpback grouper ( Cromileptes altivelis ) larvae with E. hirta methanol extract at the concentration of 1 % for 5 minutes did not give any toxic effect.