Management Of Bacterial Diseases Research Articles

MzmL, a novel marine derived N-acyl homoserine lactonase from Mesoflavibacter zeaxanthinifaciens that attenuates Pectobacterium carotovorum subsp. carotovorum virulence

Quorum sensing (QS) is a conserved cell–cell communication mechanism widely distributed in bacteria, and is oftentimes tightly correlated with pathogen virulence. Quorum quenching enzymes, which interfere with QS through degrading the QS signaling molecules, could attenuate virulence instead of killing the pathogens, and thus are less likely to induce drug resistance. Many Gram-negative bacteria produce N-acyl homoserine lactones (AHLs) for interspecies communication. In this study, we isolated and identified a bacterial strain, Mesoflavibacter zeaxanthinifaciens XY-85, from an Onchidium sp. collected from the intertidal zone of Dapeng Reserve in Shenzhen, China, and found it had strong AHL degradative activity. Whole genome sequencing and blast analysis revealed that XY-85 harbors an AHL lactonase (designated MzmL), which is predicted to have an N-terminal signal peptide and share the “HXHXDH” motif with known AHL lactonases belonging to the Metallo-β-lactamase superfamily. Phylogenetic studies showed MzmL was closest to marine lactonase cluster members, MomL and Aii20J, instead of the AiiA type lactonases. Ultra performance liquid chromatography-mass spectrometry analysis confirmed that MzmL functions as an AHL lactonase catalyzing AHL degradation through lactone hydrolysis. MzmL could degrade both short- and long-chain AHLs with or without a substitution of oxo-group at the C-3 position, and retained full bioactivity under a wide range of temperatures (28–100°C) and pHs (4–11). Furthermore, MzmL significantly reduced Pectobacterium carotovorum subsp. carotovorum virulence factor production in vitro, such as biofilm formation and plant cell wall degrading enzyme production, and inhibited soft rot development on potato slices. These results demonstrated that MzmL may be a novel type of AHL lactonase with good environmental stability, and has great potential to be developed into a novel biological control agent for bacterial disease management.

Trends of Antibacterial Interactions in Multidrug – Resistant Isolates: Exploring Resistance Phenotypes in the Ndé Division, West-Cameroon

Background: Reliable pieces of information concerning bacterial-antibiotic interactions are key assets for therapeutic management of bacterial diseases.
 Objective: The present study aimed at detecting phenotypic characteristics of bacterial resistance in multidrug-resistant isolates recovered from clinical specimens at the “Université des Montagnes” Teaching Hospital.
 Methods: The total of 226 isolates (142 Gram-negative rods and 84 Gram-positive cocci) were subjected to phenotypic screening of resistance mechanisms. All procedural steps were conducted according to standard protocols on bacterial susceptibility to antibiotics.
 Results: Primary pieces of information revealed high rates of resistant isolates, especially with beta-lactams and Trimethoprim/Sulfamethoxazole while Nitrofurantoin and Imipenem were most effective. Amongst Gram-negative rods, 56% expressed one enzymatic resistance mechanism and 12% expressed two against beta-lactams. Also, with extended spectrum beta-lactamases, high level cephalosporinases and inducible cephalosporinases most commonly observed. About 62% and 14% of Gram-positive cocci expressed constitutive and Clindamycin-inducible resistance, respectively. Decreased susceptibility to Ceftriaxone and Penicillin G was also recorded in suspect mutant isolates selected by these antibiotics. Potential synergetic and other antagonistic interactions were evenly detected.
 Conclusion: Overall, the data could represent reliable clue for advocacy about personalized combination therapy, then capacity building for routine affordable susceptibility tests in caretaking.

Diphenyl ethers from endophytic fungus Rhexocercosporidium sp. Dzf14 and their antibacterial activity by affecting homeostasis of cell membranes.

Phytopathogenic bacteria cause severe losses to crops every year. The management of crop bacterial diseases with chemical agents has been considered as the main strategy. In order to cope with the bactericide resistance made by the pathogens, new antibacterials need to be continuously developed. A chemical investigation from the endophytic fungus Rhexocercosporidium sp. Dzf14 has led to the isolation of 12 diphenyl ethers including two new ones named rhexocerin E (1) and rhexocercosporin G (2), along with two new depsides named rhexocerdepsides A (3) and B (4). The structures and absolute configurations of the new compounds were determined through comprehensive analysis of spectroscopic data and quantum chemical ECD calculations. Diphenyl ethers showed obviously antibacterial activity on Gram-positive bacteria. The structure-activity relationship of diphenyl ethers revealed that prenylation was critical to the antibacterial activity. Among them, rhexocercosporin D (12) possessed the strongest activity against Clavibacter michiganensis and Bacillus subtilis, and was selected for further mechanistic studies. It was found that rhexocercosporin D displayed bactericidal activity by affecting homeostasis of cell membranes. In addition to its rapid bactericidal effects on Gram-positive bacteria, rhexocercosporin D could restore the susceptibility against Gram-negative Agrobacterium tumefaciens by synergistic action with colistin. Twelve diphenyl ethers and two depsides were isolated from endophytic fungus Rhexocercosporidium sp. Dzf14. Isopentenyl was critical for diphenyl ethers against Gram-positive bacteria. Rhexocercosporin D could affect homeostasis of bacterial cell membrane to exert rapid bactericidal activity. These findings highlight the antibacterial potential of the diphenyl ethers in crop bacterial disease management. © 2024 Society of Chemical Industry.

The infection of Aeromonas hydrophila activated Multiple programmed cell death pathways in red blood cells of Clarias fuscus

In contrast to mammalian red blood cells (RBCs), Osteichthyes RBCs contain a nucleus and organelles, suggesting the involvement of more intricate mechanisms, particularly in the context of ferroptosis. In this study, we utilized RBCs from Clarias fuscus (referred to as Cf-RBCs) as a model system. We conducted RNA-seq analysis to quantify gene expression levels in Cf-RBCs after exposure to both Aeromonas hydrophila and lipopolysaccharides. Our analysis unveiled 1326 differentially expressed genes (DEGs) in Cf-RBCs following 4 h of incubation with A. hydrophila, comprising 715 and 611 genes with upregulated and downregulated expression, respectively. These DEGs were further categorized into functional clusters: 292 related to cellular processes, 241 involved in environmental information processing, 272 associated with genetic information processing, and 399 linked to organismal systems. Additionally, notable changes were observed in genes associated with the autophagy pathway at 4 h, and alterations in the ferroptosis pathway were observed at 8 h following A. hydrophila incubation. To validate these findings, we assessed the expression of cytokines (DMT1, TFR1, LC3, and GSS). All selected genes were significantly upregulated after exposure to A. hydrophila. Using flow cytometry, we evaluated the extent of ferroptosis, and the group incubated with A. hydrophila for 8 h exhibited higher levels of lipid peroxidation compared with the 4-h incubation group, even under baseline conditions. An evaluation of the glutathione redox system through GSSG/GSH ratios indicated an increased ratio in Cf-RBCs after exposure to A. hydrophila. In summary, our data suggest that A. hydrophila may induce ferroptosis in Cf-RBCs, potentially by triggering the cystine/glutamate antiporter system (system XC−), while Cf-RBCs counteract ferroptosis through the regulation of the glutathione redox system. These findings contribute to our understanding of the iron overload mechanism in Osteichthyes RBCs, provide insights into the management of bacterial diseases in Clarias fuscus, and offer potential strategies to mitigate economic losses in aquaculture.

Resistome and virulome of high-risk pandemic clones of multidrug-resistant extra-intestinal pathogenic Escherichia coli (ExPEC) isolated from tertiary healthcare settings in Uganda.

Multi-drug resistant (MDR) globally disseminated extraintestinal pathogenic high-risk Escherichia coli (ExPEC) clones are threatening the gains in bacterial disease management. In this study, we evaluated the genomic structure including the resistome and virulome of the E. coli isolates from extraintestinal infections using whole genome sequencing (WGS). The results highlight that isolates were highly resistant (≥ 90.0%) to commonly used antibiotics (Ampicillin, Trimethoprim-Sulfamethoxazole, Nalidixic acid, and Piperacillin) and were less (<14%) resistant to last resort antibiotics; Imipenem (10.94%) and Meropenem (10.20%). A greater proportion of the E. coli isolates belonged to phylogroup B2 (30.52%) and phylogroup A (27.37%). The sequence types ST131 of phylogroup B2 (21.05%) and ST648 of phylogroup F (9.3%) were the dominant pandemic high-risk clones identified in addition to the ST1193, ST410, ST69, ST38, ST405, and ST10. Many of the isolates were MDR and most (64.58%) carried the blaCTX-M-15 gene for extended-spectrum β-lactamases. There was a high correlation between phylogroups and the occurrence of both antimicrobial resistance and virulence genes. The cephalosporin-resistance gene blaEC-5 was only found in phylogroup B2 while blaEC-8 and blaEC-19, were only found within phylogroup D and phylogroup F respectively. Aminoglycoside gene (aadA1) was only associated with phylogroups D and C. The isolates were armed with a broad range of virulence genes including adhesins, toxins, secreted proteases, iron uptake genes, and others. The yfcv, chuA, and kpsE genes preferentially occurred among isolates of phylogroup B2. The study underlines the predominance of MDR internationally disseminated high-risk ExPEC clones with a broad range of virulence genes known to be highly transmissible in healthcare and community settings.

Revitalizing pond culture system: Harnessing the power of composite nanopeptide C[sbnd]I20, 1,3-1,6-β-glucan, and anthocyanidin biotherapy as an antibiotic substitute for efficient management of bacterial diseases in bullfrogs

Bacterial diseases in aquaculture ponds have significant negative effects on sustainable development. Antibiotic resistance in aquatic pathogens has reduced the effectiveness of traditional treatments. To address this, composite additives that boost the natural defense system are being explored. In this study, we focused on four common symptoms in bullfrog ponds: amyosthenia, black body color, crooked head, and pythiosis. We also observed overlapping symptoms such as amyosthenia + crooked head and black body color + pythiosis. The overall incidence rate of these symptoms was 85.6%, with Aeromonas hydrophila and Elizabethkingia miricola identified as the responsible pathogens. To treat bullfrog bacterial diseases, we used two treatments: florfenicol (FF) at 20 mg/Kg and a composite I20 (CI) containing nanopeptide CI20 (2 g/Kg), β-glucan (1 g/Kg), and anthocyanidin (1 g/Kg). We implemented a staged therapy approach, comprising initial assessment, self-cure intervention, and continuous treatment stages, along with continuous monitoring to assess the effectiveness and usage protocol of CI. In the initial therapy stage, oral CI or florfenicol improved body color and rapidly reduced morbidity rate and daily mortality rate. CI biological agent exerted anti-bacterial infection by improving mucosal barrier, antioxidant enzyme activity (T-AOC and TSOD), and innate immunity index (LZM activity, leukocyte number). The CI treatment demonstrated significant reductions in tissue injury (intestine, liver, spleen) and tissue bacterial load. Following the stage therapy, the CI group exhibited lower morbidity and daily mortality rates compared to the FF group. Additionally, the total protection rate of the CI group surpassed that of the FF and control groups during the stage therapy. The antibiotic resistance and drug resistance genes (FIoR and FexA) and virulence genes (HxlR, ClpP, OmpA, and FlaA) in A. hydrophila and E. mirabilis were markedly induced by florfenicol treatment, respectively. In continuing therapy stage (42 days), the morbidity, protection rate, and daily mortality of the CI group were better than that of the FF group. In conclusion, composite I20 biotherapy effectively treats the bacterial disease of bullfrogs in pond system, providing a prospectively novel strategy for controlling bacterial disease in aquaculture.

Green nanotechnology for plant bacterial diseases management in cereal crops: a review on metal-based nanoparticles

Cereals are an important source of nutrients for animals. Several diseases cause severe yield loss in cereal crops. Bacterial diseases result in varying yield losses across cereals: Wheat (5-40%), maize (15-98.9%), rice (20-70%), pearl millet (3-35%), and oats (15-49%). Diseases may be bacterial diseases, fungal or viral. Bacterial diseases are traditionally treated by pesticides. Chemically synthesized pesticides are toxic and hazardous to the environment. Nanotechnology is emerging and novel field for agriculture, especially in plant pathology as a strong antimicrobial agent. Nanoparticles have been synthesized in various ways i.e., biological, physical, and chemical methods. Chemical and physical methods of nanoparticles are costly and toxic to the environment. The biological method for the synthesis of nanoparticles is eco-friendly and economical. Microorganisms or plant extracts are used for metal nanoparticle synthesis. The application of nanoparticles in agriculture has a wide scope and it can bring nano-revolution. This review summarizes the antibacterial activity of biosynthesized metal nanoparticles and their role in bacterial disease management of cereals.

The Potential Role of Vaccines in Preventing Antimicrobial Resistance (AMR): An Update and Future Perspectives.

In the modern era, the consumption of antibiotics represents a revolutionary weapon against several infectious diseases, contributing to the saving of millions of lives worldwide. However, the misuse of antibiotics for human and animal purposes has fueled the process of antimicrobial resistance (AMR), considered now a global emergency by the World Health Organization (WHO), which significantly increases the mortality risk and related medical costs linked to the management of bacterial diseases. The current research aiming at developing novel efficient antibiotics is very challenging, and just a few candidates have been identified so far due to the difficulties connected with AMR. Therefore, novel therapeutic or prophylactic strategies to fight AMR are urgently needed. In this scenario, vaccines constitute a promising approach that proves to be crucial in preventing pathogen spreading in primary infections and in minimizing the usage of antibiotics following secondary bacterial infections. Unfortunately, most of the vaccines developed against the main resistant pathogens are still under preclinical and clinical evaluation due to the complexity of pathogens and technical difficulties. In this review, we describe not only the main causes of AMR and the role of vaccines in reducing the burden of infectious diseases, but we also report on specific prophylactic advancements against some of the main pathogens, focusing on new strategies that aim at improving vaccine efficiency.

Current trends in management of bacterial pathogens infecting plants.

Plants are continuously challenged by different pathogenic microbes that reduce the quality and quantity of produce and therefore pose a serious threat to food security. Among them bacterial pathogens are known to cause disease outbreaks with devastating economic losses in temperate, tropical and subtropical regions throughout the world. Bacteria are structurally simple prokaryotic microorganisms and are diverse from a metabolic standpoint. Bacterial infection process mainly involves successful attachment or penetration by using extracellular enzymes, type secretion systems, toxins, growth regulators and by exploiting different molecules that modulate plant defence resulting in successful colonization. Theses bacterial pathogens are extremely difficult to control as they develop resistance to antibiotics. Therefore, attempts are made to search for innovative methods of disease management by the targeting bacterial virulence and manipulating the genes in host plants by exploiting genome editing methods. Here, we review the recent developments in bacterial disease management including the bioactive antimicrobial compounds, bacteriophage therapy, quorum-quenchingmediated control, nanoparticles and CRISPR/Cas based genome editing techniques for bacterial disease management. Future research should focus on implementation of smart delivery systems and consumer acceptance of these innovative methods for sustainable disease management.

Future of Bacterial Disease Management in Crop Production.

Bacterial diseases are a constant threat to crop production globally. Current management strategies rely on an array of tactics, including improved cultural practices; application of bactericides, plant activators, and biocontrol agents; and use of resistant varieties when available. However, effective management remains a challenge, as the longevity of deployed tactics is threatened by constantly changing bacterial populations. Increased scrutiny of the impact of pesticides on human and environmental health underscores the need for alternative solutions that are durable, sustainable, accessible to farmers, and environmentally friendly. In this review, we discuss the strengths and shortcomings of existing practices and dissect recent advances that may shape the future of bacterial disease management. We conclude that disease resistance through genome modification may be the most effective arsenal against bacterial diseases. Nonetheless, more research is necessary for developing novel bacterial disease management tactics to meet the food demand of a growing global population.

Efficacy of PostivaTM for Management of Bacterial Diseases of Ornamental Crops

Pathogen management commonly includes environmental regulation and sanitization. There are limited numbers of effective registered bactericides. In 3 years of greenhouse trials, PostivaTM, a premix of pydiflumetofen (6.9%) and difenoconazole (11.5%), was tested for activity against xanthomonas leafspot of geranium, zinnia, ficus and bacterial wilt of geranium caused by Ralstonia solanacearum. PostivaTM applied at 0.73–1.5 L/ha significantly reduced disease incidence and/or severity on each crop tested. PostivaTM applications were similar (p = 0.05) to commercially available standards on geranium, zinnia and ficus. PostivaTM (0.73 L/ha) reduced incidence and severity of bacterial wilt similar to that observed with applications of Cease® (9.35 L/ha). PostivaTM may be beneficial in an integrated disease management program to control bacterial diseases. PostivaTM is highly promising as a rotation option to reduce the buildup of bacterial populations resistant to copper compounds and antibiotics that are frequently used in the industry.

Pharmacokinetics, bioavailability and withdrawal period of antibiotic oxytetracycline in catfish Pangasianodon hypophthalmus

The antibiotic oxytetracycline (OTC) has been widely used for therapeutic and preventive management of bacterial diseases in finfish and shellfish. In the present study the bioavailability, pharmacokinetics, and withdrawal period of the OTC have been determined following in-feed administration in intensively cultured catfish Pangasianodon hypophthalmus. Furthermore, the pharmacokinetic parameters of oral route were also compared with parenteral route. Drug concentrations were measured in various tissues at different time intervals by LC-MS/MS. The study revealed the drug kinetics best followed the enterohepatic circulation model with very poor bioavailability and low blood concentration after oral administration. In the withdrawal study, after 10-days of in-feed administration at the therapeutic dose the drug reached very high concentrations in the liver and kidneys but did not attain minimum inhibitory concentrations (MICs) in blood or flesh. OTC concentration also did not exceed the recommended MRL value in flesh; however, considering high amounts of the chemical in the liver and kidneys a withdrawal period of 4 days (at 28 ± 1.5 oC) is recommended for consumer safety. Poor bioavailability and non-attainment of minimum therapeutic concentration in blood and flesh do not warrant in-feed administration of OTC for control of bacterial diseases in P. hypophthalmus. Availability of data and materialsAll data generated and analyzed during this study are included in this article. Raw data may be shared upon reasonable request.

Evaluation of the Agromorphological Determinants of the Spread of the Bacterial Disease in Orchards of the Main Mango-Producing Regions in Côte d'Ivoire

The use of agroecological practices for the management of phytosanitary problems has become a major issue in the context of sustainable development. It is with this in mind that this study was initiated in the regions of Bagoué, Poro and Tchologo. This study consisted of investigating the determinants likely to promote the spread of the bacterial disease in 720 mango trees of the Kent variety distributed in 20 orchards in the regions of Poro, Tchologo and Bagoué. During this study, the incidence and severity of bacterial disease on leaves and fruits (IsFe, IsFr, IcFe, IcFr) as well as agromorphological parameters such as East-West and North-South spans, total leaf area, fruit load, trunk circumference, total height and number of main branches (En EO and NS, SFT, ChFr, CirTr, HaTr and RamP) were measured. The performance of the pearson correlation test revealed that spans (N-S and E-O), HaTr, SFT and ChFr are the 4 agromorphological determinants that promote the spread of bacteriosis in orchards of the three (3) regions. The synthesis of the results of the ACP and the CAH supplemented by a multivariate analysis (MANOVA) made it possible to structure the mango orchards into three (3) homogeneous groups. Group 1 orchards (VB4, VB8, VS1, VF5, VK1, VB7, VF2 and VK2) expressed the lowest severity indices and the incidence of bacteriosis on the leaves (respectively 15.21 ± 8.87% ; 12.21 ± 6.54%) and fruits (respectively 13.11 ± 4.75%; 10.40 ± 2.93%). These orchards featured mango trees with medium trunk circumferences (99.14 ± 17.24 cm), medium trunk heights (145.29 ± 7.24 cm) and smallest spans (6.85 ± 1, 13 m for the NS span and 6.79 ± 1.18 m for the EO span) and total leaf area (15.61 ± 0.06 cm). These results could help develop an agroecological control strategy for the sustainable management of bacterial disease.

Evaluation of the Behavior of Cashew Genotypes with Regard to Bacterial Disease in Agroforestry Farms in Northern Côte d'Ivoire

Notwithstanding the inflows of currency for the populations who practice it, the cultivation of the cashew tree contributes to strengthening the forestry agrosystem in Côte d'Ivoire. However, this culture, with multiple interests, is confronted with attacks from parasites including bacterial disease. Bacterial disease causes extensive damage to vegetative organs as well as fruits and causes yield losses. The objective of this study is to assess the behavior of cashew genotypes in relation to the severity and incidence of bacterial disease in the context of agroforestry production in Côte d'Ivoire.&#x0D; To achieve this objective, 1.200 branches were observed to assess the tolerance or sensitivity of 30 cashew trees in agroforestry orchards of cashew trees in the localities of Korhogo, Sinématiali and Boundiali. These cashew genotypes were selected and geolocated. The factor studied is the cashew genotype, composed of 30 cashew genotypes, with 6 modalities which are the severity index of bacterial disease on leaves, twigs and nuts, the incidence of bacterial disease. bacterial disease on leaves, twigs and nuts. The data collected that are the index of severity of bacterial disease on leaves, twigs and nuts, the incidence of bacterial disease on leaves, twigs and nuts have made the subject to descriptive analysis and PCA. The ascending hierarchical classification (HAC) and multivariate analysis completed the data analysis. The results obtained revealed three groups of cashew trees. Those of group 3 made up of twelve (12) genotypes, namely SYDN, SDYY, SDYN and KBSD coming from the localities of Sinématiali and Korhogo, differ from the others by a weak infection of the nuts (8.67 ± 2.74). The genotypes in this group are more resilient and their development in an agroforestry system could help promote agroecological management of bacterial disease, improve and intensify agroforestry practices in C. d'Ivoire.

Using magnesium oxide nanomaterial as a novel tool for bacterial disease management

ISHS VI International Symposium on Tomato Diseases: Managing Tomato Diseases in the Face of Globalization and Climate Change Using magnesium oxide nanomaterial as a novel tool for bacterial disease management

Rapid Loop-Mediated Isothermal Amplification for Detection of the Ralstonia solanacearum Species Complex Bacteria in Symptomatic Potato Tubers and Plants.

The Ralstonia solanacearum species complex (RSSC) is composed of several Ralstonia species and strains that are little related and show varied host range and distinct geographic distributions. The RSSC causes wilt disease, and can thus have severe economic consequences for many important crops and ornamental plants. One such is potato (Solanum tuberosum), where infection causes brown rot of the tubers. It is important that symptomatic tubers and plants can be rapidly and easily tested, as exclusion of infected material is a cornerstone of management of bacterial diseases. A suitable method is loop-mediated isothermal amplification, a rapid, DNA-based method that can be used for specific detection of plant pathogens in infected materials. The combination of this loop-mediated isothermal amplification assay for the RSSC with a simple sample preparation method is fit for purpose for identification of this devastating disease in symptomatic tubers and plants. This methodology is rapid and cost efficient, and can be carried out outside of conventional laboratory facilities.

Practical Management of Bacterial Diseases in Finfish Aquaculture to Minimise Antimicrobial Resistance

Practical Management of Bacterial Diseases in Finfish Aquaculture to Minimise Antimicrobial Resistance

Study of quorum quenching bacteria Cobetia sp. reducing the mortality of Penaeus vannamei infected with Vibrio harveyi: in vitro and in vivo tests

Finding alternative measures to antibiotics for shrimp bacterial disease management is a current need. The application of quorum quenching (QQ) bacteria to prevent bacterial diseases in aquaculture is a current research hotspot, but the effect and mechanism of QQ bacteria in the practical application of shrimp farming requires further exploration. In the present study, in vitro and in vivo tests were conducted to comprehensively analyze the effect and mechanism of the QQ bacteria W1B (Cobetia sp.) in preventing shrimp vibriosis caused by Vibrio harveyi HAH. Cocultivation of strains W1B and HAH was used to conduct an in vitro test. Strain W1B and its intracellular and extracellular proteins could significantly reduce the concentration of quorum sensing (QS) signaling molecules (AHLs) of V. harveyi HAH without affecting its growth. The intracellular proteins of strain W1B could significantly reduce the expression of the QS regulatory gene luxR and virulence genes of strain HAH. An in vivo test was performed by adding strain W1B to shrimp culture water. Shrimp were cultured for 35 days, and then a challenge test was performed by injecting strain HAH into the shrimp. The results showed that strain W1B at low concentrations (1 × 104 CFU·mL−1) reduced the expression of shrimp immune genes and that high concentrations (1 × 106 CFU·mL−1) increased the expression of SOD, LZM, and IMD. In the challenge test, strain W1B could significantly reduce the mortality and protect the hepatopancreas epithelial cells of shrimp. Additionally, strain W1B could change the expression patterns of shrimp immune-related genes. The relative expression levels of the QS regulatory gene and virulence genes of strain HAH in the shrimp hepatopancreas were significantly downregulated by strain W1B. Additionally, strain W1B significantly reduced the relative expression of shrimp apoptosis-related genes. The above results indicated that QQ strain W1B could inhibit the transcriptional expression of V. harveyi luxR and induce the downregulation of virulence gene expression, thereby reducing V. harveyi pathogenicity. Ultimately, strain W1B could reduce shrimp mortality. These findings can provide new methods and basic data for the prevention and treatment of shrimp bacterial diseases.

Bacteriophage Usage for Bacterial Disease Management and Diagnosis in Plants.

In nature, plants are always under the threat of pests and diseases. Pathogenic bacteria are one of the major pathogen types to cause diseases in diverse plants, resulting in negative effects on plant growth and crop yield. Chemical bactericides and antibiotics have been used as major approaches for controlling bacterial plant diseases in the field or greenhouse. However, the appearance of resistant bacteria to common antibiotics and bactericides as well as their potential negative effects on environment and human health demands bacteriologists to develop alternative control agents. Bacteriophages, the viruses that can infect and kill only target bacteria very specifically, have been demonstrated as potential agents, which may have no negative effects on environment and human health. Many bacteriophages have been isolated against diverse plant-pathogenic bacteria, and many studies have shown to efficiently manage the disease development in both controlled and open conditions such as greenhouse and field. Moreover, the specificity of bacteriophages to certain bacterial species has been applied to develop detection tools for the diagnosis of plant-pathogenic bacteria. In this paper, we summarize the promising results from greenhouse or field experiments with bacteriophages to manage diseases caused by plant-pathogenic bacteria. In addition, we summarize the usage of bacteriophages for the specific detection of plant-pathogenic bacteria.

Identification of Pathogenic Bacteria from Diseased Thai Pangas Pangasius hypophthalmus with Their Sensitivity to Antibiotics

Thai Pangas (Pangasiaus hypophthalmus) has been emerging as an economically very important species due their faster growth, year round production and high productivity in South-East Asian aquaculture. It has good market value as a food fish due to its good taste and deliciousness with high protein, minerals and fat content. It is also popular as a game fish.&#x0D; Aims: The present study was conducted to identify bacterial pathogens in diseased P. hypophthalmus and evaluate their sensitivity to antibiotics.&#x0D; Methodology: To identify the causativeagent of diseased fish pure culture of bacteria using slant and streak plate techniques and different biochemical tests such as Gram’s Staining, Motility Test, Sugar Fermentation Test, MR-VP test, Indole Test etc. were performed. To assess the sensitivity of the isolated bacteria to antibiotics five antibiotics disks i.e. Ciprofloxacin (5μg), Azithromycin (15μg), Ampicillin/Sulbactam (20μg), Tetracycline (30μg) and Erythromycin (15μg) were used.&#x0D; Results: Three pathogenic bacteria i.e. Aeromonas hydrophila, Edwardsiella ictaluri and Pseudomonas sp. were identified in the studied diseased fish. Only Pseudomonas sp. were identified from Fresh fish. E. ictaluri was found only in diseased pangas which was the causative agent for thedisease, Bacillary Necrosis. The results of the antibiotic sensitivity test showed multi-resistances of the identified bacteria to the tested antibiotics. The identified bacteria were 100% sensitive to Ciprofloxacin (5μg), intermediate to Azithromycin (15μg) and Tetracycline (30μg), but resistant to Erythromycin (15μg) and Ampicilin/Sulbactam (20μg).&#x0D; Conclusion: Ciprofloxacin (5µg) could be used to control bacillary necrosis disease in Thai pangas. The results of this study will be helpful to the fish farmers for the management of bacterial diseases in fish.