scholarly journals Seasonal Incidence of Autochthonous Antagonistic Roseobacter spp. and Vibrionaceae Strains in a Turbot Larva (Scophthalmus maximus) Rearing System

2004 ◽  
Vol 70 (12) ◽  
pp. 7288-7294 ◽  
Author(s):  
Mette Hjelm ◽  
Ana Riaza ◽  
Fernanda Formoso ◽  
Jette Melchiorsen ◽  
Lone Gram
Keyword(s):  
Pathogenic Bacteria ◽  
Vibrio Anguillarum ◽  
Scophthalmus Maximus ◽  
Antagonistic Activity ◽  
Early Summer ◽  
Rrna Gene ◽  
Fish Farms ◽  
Biochemical Tests ◽  
Seasonal Incidence ◽  
Regular Source

ABSTRACT Bacteria inhibitory to fish larval pathogenic bacteria were isolated from two turbot larva rearing farms over a 1-year period. Samples were taken from the rearing site, e.g., tank walls, water, and feed for larvae, and bacteria with antagonistic activity against Vibrio anguillarum were isolated using a replica plating assay. Approximately 19,000 colonies were replica plated from marine agar plates, and 341 strains were isolated from colonies causing clearing zones in a layer of V. anguillarum. When tested in a well diffusion agar assay, 173 strains retained the antibacterial activity against V. anguillarum and Vibrio splendidus. Biochemical tests identified 132 strains as Roseobacter spp. and 31 as Vibrionaceae strains. Partial sequencing of the 16S rRNA gene of three strains confirmed the identification as Roseobacter gallaeciensis. Roseobacter spp. were especially isolated in the spring and early summer months. Subtyping of the 132 Roseobacter spp. strains by randomly amplified polymorphic DNA with two primers revealed that the strains formed a very homogeneous group. Hence, it appears that the same subtype was present at both fish farms and persisted during the 1-year survey. This indicates either a common, regular source of the subtype or the possibility that a particular subtype has established itself in some areas of the fish farm. Thirty-one antagonists were identified as Vibrio spp., and 18 of these were V. anguillarum but not serotype O1 or O2. Roseobacter spp. strains were, in particular, isolated from the larval tank walls, and it may be possible to establish an antagonistic, beneficial microflora in the rearing environment of turbot larvae and thereby limit survival of pathogenic bacteria.

scholarly journals Antimicrobial Potential of Rhizospheric Bacteria Streptobacillus sp.

2021 ◽  
Author(s):  
Jay Kishor Prasad ◽  
Riddha Dey ◽  
Richa Raghuwanshi
Keyword(s):  
Pathogenic Bacteria ◽  
Antagonistic Activity ◽  
Diffusion Method ◽  
Disc Diffusion Method ◽  
Biochemical Tests ◽  
Good Source ◽  
Rhizospheric Bacteria ◽  
Wide Range ◽  
And Staphylococcus Aureus ◽  
Agar Well Diffusion Method

Rhizospheric bacteria exhibiting antagonistic effects are a good source for the production of antibiotics. The antibiotics produced are naturally bactericidal or bacteriostatic in nature. In the present investigation, thirty-five rhizospheric bacteria were isolated from different soil samples. Agar well diffusion method, streak agar method, disc diffusion method and biochemical tests were performed to screen the ten antibiotic-producing bacteria. Among them, strain JRR34 selected on the basis of primary antagonistic activity was identified as Streptobacillus sp. Media optimisation was done to ensure maximum production of secondary metabolites. Streptobacillus sp. JRR34 showed good inhibitory activity against Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus. The ethyl crude extract of Streptobacillus sp. JRR34 rhizobacteria possessing good antagonistic activity against a wide range of pathogenic bacteria can be a vital source of novel antibiotics.

scholarly journals The Predatory Myxobacterium Citreicoccus inhibens gen. nov. sp. nov. Showed Antifungal Activity and Bacteriolytic Property against Phytopathogens

2021 ◽  
Vol 9 (10) ◽  
pp. 2137
Author(s):  
Yang Zhou ◽  
Shuoxing Yi ◽  
Yi Zang ◽  
Qing Yao ◽  
Honghui Zhu
Keyword(s):  
Antifungal Activity ◽  
Pathogenic Bacteria ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Extracellular Proteins ◽  
Morphological Observation ◽  
Rrna Gene ◽  
Fruiting Body Formation ◽  
Predatory Bacteria ◽  
Beneficial Traits

The application and promotion of biological control agents are limited because of poor efficacy and unstable performance in the field. Screening microorganisms with high antagonistic activity, effective adaptability, and high field-survival should be prospected. Myxobacteria are soil predatory bacteria with wide adaptability, which are considered as good antagonists. Here, we report a myxobacterium strain M34 isolated from subtropical forest soil in South China using the Escherichia coli baiting method. Based on the morphological observation, physiological test, biochemical characteristics, 16S rRNA gene sequence, and genomic data, strain M34 was identified as a novel genus and novel species, representing a new clade of Myxococcaceae, for which the name Citreicoccus inhibens gen. nov. sp. nov. is proposed (type strain M34T = GDMCC 1.2275T = KCTC 82453T). The typical features of M34, including fruiting body formation and extracellular fibrillar interconnection, indicated by microscopic observations, contributed to cell adaption in different environments. Furthermore, the strain showed antifungal activity against phytopathogenic fungi and predatory activity to both Gram-negative and Gram-positive phytopathogenic bacteria. The bioprotective mechanisms are attributed to the presence of pyrrolnitrin and derivative with antifungal activity and the extracellular proteins with lytic activity against pathogenic bacteria. Due to its multiple beneficial traits, strain M34 has the potential to be developed into a versatile biocontrol agent for the management of both fungal and bacterial phytopathogens.

scholarly journals Antagonistic Potential of Soil Streptomyces Isolates from Southern Thailand to Inhibit Foodborne Bacterial Pathogens

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Waenurama Chemoh ◽  
Wahida Bin-Ismail ◽  
Sawitree Dueramae
Keyword(s):  
Antibacterial Activity ◽  
Pathogenic Bacteria ◽  
Bacterial Pathogens ◽  
Antagonistic Activity ◽  
Rrna Gene ◽  
Rice Soils ◽  
Streptomyces Species ◽  
Genus Streptomyces ◽  
Crude Extracts ◽  
Broth Microdilution Method

Streptomyces are well known for their competence to produce thousands of bioactive secondary metabolites and enzymes. This study aimed to assess the inhibitory activities of crude extracts from diverse Streptomyces collected from rice soils in Narathiwat, Thailand, against foodborne bacterial pathogens. In total, 136 Actinomycete isolates were screened using a cross-streak method for the ability to produce effective metabolites against 5 pathogenic bacteria. Out of these, 19 (13.97%) isolates had antibacterial activity against at least one tested bacterium. Most of the isolates could strongly suppress the growth of S. aureus ATCC25923 and B. cereus MTCC430 except P. aeruginosa ATCC27853. On the basis of morphological, cultural, and biochemical characteristics, all potent isolates exhibited typical features that fitted the genus Streptomyces. Two of the 7 selected ethyl acetate crude extracts had good antagonistic activity against S. aureus ATCC25923 and B. cereus MTCC430 when tested using the agar well diffusion assay. Furthermore, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values of the 2 extracts evaluated using the colorimetric broth microdilution method ranged from 256 to >1,024 μg/ml against the tested bacteria. The partial nucleotide sequences of the 16S rRNA gene led to identifying both active isolates as Streptomyces species. These active Streptomyces isolates could provide an interesting source for generating innumerable natural compounds with antibacterial activity that can presumably be developed to fight bacterial pathogens in the near future.

scholarly journals Molecular Identification and Characterization of Smartphone Screen Associated Pathogenic Bacteria

2020 ◽  
pp. 94-103 ◽  
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Contamination ◽  
Saline Water ◽  
Antibiotic Sensitivity ◽  
Coagulase Negative Staphylococcus ◽  
Rrna Gene ◽  
Body Parts ◽  
Biochemical Tests ◽  
Gram Positive ◽  
Gram Negative

Mobile phone is a device that keeps in contact with our sensitive body parts including faces, hands, nose, ears, and lips, etc. most of the time. Although we know many bad aspects of mobile phones; we are indifferent to its bacterial contamination. Smartphone screen is an endless reservoir of pathogenic bacteria and works as an object in spreading those bacteria. The purpose of the study was to identify pathogenic bacteria from smartphone screen and finding some common causes of bacterial contamination. So, a public survey was conducted among 100 students from the Dept. of Genetic Engineering & Biotechnology, University of Rajshahi to know the uses pattern of their particular smartphone. Then, for the lab-based work samples were collected from the smartphone screen of the students by sterile swabs moistened with normal saline water. Among the samples, four strains were selected based on bacterial concentration for further analysis. Out of four, two strains were gram-positive and two were gram-negative. Biochemical tests indicated that all of them were pathogenic and the selected gram-positive bacteria were coagulase-positive Staphylococcus species and coagulase-negative Staphylococcus species.16S-rRNA gene sequencing identified the selected two-gram negative strains as Stenotrophomonas maltophilia and Klebsiella pneumoniae. The antibiotic sensitivity test referred that all the bacteria were multidrug-resistant and may be dangerous for compromised immune patients.

Effect of the endophytic plant growth promoting Enterobacter ludwigii EB4B on tomato growth

2020 ◽  
Vol 13 (2) ◽  
pp. 54-65 ◽  
Author(s):  
M.E.A. Bendaha ◽  
H.A. Belaouni
Keyword(s):  
Root Length ◽  
Biocontrol Agent ◽  
Growth Promotion ◽  
Dry Weight ◽  
Antagonistic Activity ◽  
Rrna Gene ◽  
Plant Growth Promoting ◽  
Enterobacter Ludwigii ◽  
Tomato Growth

SummaryThis study aims to develop a biocontrol agent against Fusarium oxysporum f.sp. radicis-lycopersici (FORL) in tomato. For this, a set of 23 bacterial endophytic isolates has been screened for their ability to inhibit in vitro the growth of FORL using the dual plate assay. Three isolates with the most sound antagonistic activity to FORL have been qualitatively screened for siderophore production, phosphates solubilization and indolic acetic acid (IAA) synthesis as growth promotion traits. Antagonistic values of the three candidates against FORL were respectively: 51.51 % (EB4B), 51.18 % (EB22K) and 41.40 % (EB2A). Based on 16S rRNA gene sequence analysis, the isolates EB4B and EB22K were closely related to Enterobacter ludwigii EN-119, while the strain EB2A has been assigned to Leclercia adecarboxylata NBRC 102595. The promotion of tomato growth has been assessed in vitro using the strains EB2A, EB4B and EB22K in presence of the phytopathogen FORL. The treatments with the selected isolates increased significantly the root length and dry weight. Best results were observed in isolate EB4B in terms of growth promotion in the absence of FORL, improving 326.60 % of the root length and 142.70 % of plant dry weight if compared with untreated controls. In the presence of FORL, the strain EB4B improved both root length (180.81 %) and plant dry weight (202.15 %). These results encourage further characterization of the observed beneficial effect of Enterobacter sp. EB4B for a possible use as biofertilizer and biocontrol agent against FORL.

scholarly journals First reported quantitative microbiota in different livestock manures used as organic fertilizers in the Northeast of Thailand

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Lampet Wongsaroj ◽  
Ratmanee Chanabun ◽  
Naruemon Tunsakul ◽  
Pinidphon Prombutara ◽  
Somsak Panha ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Organic Fertilizer ◽  
The Other ◽  
Organic Fertilizers ◽  
Rrna Gene ◽  
Bacterial Composition ◽  
Physiochemical Properties ◽  
Nutrient Profiles ◽  
Soil Recovery ◽  
Local Farmers

AbstractNortheastern Thailand relies on agriculture as a major economic activity, and has used high levels of agrochemicals due to low facility, and salty sandy soil. To support soil recovery and sustainable agriculture, local farmers have used organic fertilizers from farmed animal feces. However, knowledge about these animal fecal manures remains minimal restricting their optimal use. Specifically, while bacteria are important for soil and plant growth, an abundance and a diversity of bacterial composition in these animal fecal manures have not been reported to allow selection and adjustment for a more effective organic fertilizer. This study thereby utilized metagenomics combined with 16S rRNA gene quantitative PCR (qPCR) and sequencing to analyze quantitative microbiota profiles in association with nutrients (N, P, K), organic matters, and the other physiochemical properties, of the commonly used earthworm manure and other manures from livestock animals (including breed and feeding diet variations) in the region. Unlike the other manures, the earthworm manure demonstrated more favorable nutrient profiles and physiochemical properties for forming fertile soil. Despite low total microbial biomass, the microbiota were enriched with maximal OTUs and Chao richness, and no plant pathogenic bacteria were found based on the VFDB database. The microbial metabolic potentials supported functions to promote crop growth, such as C, N and P cyclings, xenobiotic degradation, and synthesis of bioactive compounds. Pearson’s correlation analyses indicated that the quantitative microbiota of the earthworm manure were clustered in the same direction as N, and conductivity, salinity, and water content were essential to control the microbiota of animal manures.

scholarly journals Identification of an N-acetylneuraminic acid-presenting bacteria isolated from a human microbiome

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhen Han ◽  
Peter S. Thuy-Boun ◽  
Wayne Pfeiffer ◽  
Vincent F. Vartabedian ◽  
Ali Torkamani ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Human Microbiome ◽  
Host Immunity ◽  
Rrna Gene ◽  
Metabolic Labeling ◽  
Selective Labeling ◽  
Fecal Microbiome ◽  
Acetylneuraminic Acid ◽  
Intestinal Mucus ◽  
Microbial Systems

AbstractN-Acetylneuraminic acid is the most abundant sialic acid (SA) in humans and is expressed as the terminal sugar on intestinal mucus glycans. Several pathogenic bacteria harvest and display host SA on their own surfaces to evade Siglec-mediated host immunity. While previous studies have identified bacterial enzymes associated with SA catabolism, no reported methods permit the selective labeling, tracking, and quantitation of SA-presenting microbes within complex multi-microbial systems. We combined metabolic labeling, click chemistry, 16S rRNA gene, and whole-genome sequencing to track and identify SA-presenting microbes from a cultured human fecal microbiome. We isolated a new strain of Escherichia coli that incorporates SA onto its own surface and encodes for the nanT, neuA, and neuS genes necessary for harvesting and presenting SA. Our method is applicable to the identification of SA-presenting bacteria from human, animal, and environmental microbiomes, as well as providing an entry point for the investigation of surface-expressed SA-associated structures.

scholarly journals Nanopore-Sequencing Characterization of the Gut Microbiota of Melolontha melolontha Larvae: Contribution to Protection against Entomopathogenic Nematodes?

Pathogens ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 396
Author(s):  
Ewa Sajnaga ◽  
Marcin Skowronek ◽  
Agnieszka Kalwasińska ◽  
Waldemar Kazimierczak ◽  
Karolina Ferenc ◽  
...  
Keyword(s):  
Gut Microbiota ◽  
Entomopathogenic Nematodes ◽  
Bacterial Species ◽  
Antagonistic Activity ◽  
Rrna Gene ◽  
Nanopore Sequencing ◽  
Bacterial Phyla ◽  
Melolontha Melolontha

This study focused on the potential relationships between midgut microbiota of the common cockchafer Melolontha melolontha larvae and their resistance to entomopathogenic nematodes (EPN) infection. We investigated the bacterial community associated with control and unsusceptible EPN-exposed insects through nanopore sequencing of the 16S rRNA gene. Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the most abundant bacterial phyla within the complex and variable midgut microbiota of the wild M. melolontha larvae. The core microbiota was found to include 82 genera, which accounted for 3.4% of the total number of identified genera. The EPN-resistant larvae differed significantly from the control ones in the abundance of many genera belonging to the Actinomycetales, Rhizobiales, and Clostridiales orders. Additionally, the analysis of the microbiome networks revealed different sets of keystone midgut bacterial genera between these two groups of insects, indicating differences in the mutual interactions between bacteria. Finally, we detected Xenorhabdus and Photorhabdus as gut residents and various bacterial species exhibiting antagonistic activity against these entomopathogens. This study paves the way to further research aimed at unravelling the role of the host gut microbiota on the output of EPN infection, which may contribute to enhancement of the efficiency of nematodes used in eco-friendly pest management.

scholarly journals Detection of Food Spoilage and Pathogenic Bacteria Based on Ligation Detection Reaction Coupled to Flow-Through Hybridization on Membranes

2014 ◽  
Vol 2014 ◽  
pp. 1-11 ◽  
Author(s):  
K. Böhme ◽  
P. Cremonesi ◽  
M. Severgnini ◽  
Tomás G. Villa ◽  
I. C. Fernández-No ◽  
...  
Keyword(s):  
Pathogenic Bacteria ◽  
Bacterial Species ◽  
Cost Effective ◽  
Rrna Gene ◽  
Bacterial Identification ◽  
Dot Blot ◽  
Culture Collections ◽  
Ligation Detection Reaction ◽  
Flow Through ◽  
Food Safety And Quality

Traditional culturing methods are still commonly applied for bacterial identification in the food control sector, despite being time and labor intensive. Microarray technologies represent an interesting alternative. However, they require higher costs and technical expertise, making them still inappropriate for microbial routine analysis. The present study describes the development of an efficient method for bacterial identification based on flow-through reverse dot-blot (FT-RDB) hybridization on membranes, coupled to the high specific ligation detection reaction (LDR). First, the methodology was optimized by testing different types of ligase enzymes, labeling, and membranes. Furthermore, specific oligonucleotide probes were designed based on the 16S rRNA gene, using the bioinformatic tool Oligonucleotide Retrieving for Molecular Applications (ORMA). Four probes were selected and synthesized, being specific forAeromonasspp.,Pseudomonasspp.,Shewanellaspp., andMorganella morganii, respectively. For the validation of the probes, 16 reference strains from type culture collections were tested by LDR and FT-RDB hybridization using universal arrays spotted onto membranes. In conclusion, the described methodology could be applied for the rapid, accurate, and cost-effective identification of bacterial species, exhibiting special relevance in food safety and quality.

scholarly journals Nocardioides panacihumi sp. nov., isolated from soil of a ginseng field

2007 ◽  
Vol 57 (9) ◽  
pp. 2143-2146 ◽  
Author(s):  
Dong-Shan An ◽  
Wan-Taek Im ◽  
Sung-Taik Lee ◽  
Min-Ho Yoon
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Major Fatty Acid ◽  
Rrna Gene ◽  
Strictly Aerobic ◽  
Biochemical Tests ◽  
Phenotypic Differentiation ◽  
The Family ◽  
Established Species ◽  
Type Strains

A novel bacterial strain designated Gsoil 616T was isolated from a soil sample of a ginseng field in Pocheon province (South Korea) and was characterized taxonomically by using a polyphasic approach. The isolate was Gram-positive, strictly aerobic, non-motile, non-spore-forming and rod- or coccoid-shaped. Phylogenetic analysis based on 16S rRNA gene sequences indicated that the isolate belongs to the genus Nocardioides in the family Nocardioidaceae but was clearly separated from established species of this genus. The 16S rRNA gene sequence similarities between strain Gsoil 616T and the type strains of Nocardioides species with validly published names ranged from 91.8 to 96.1 %. The G+C content of the genomic DNA was 73 mol%. Phenotypic and chemotaxonomic data [major menaquinone MK-8(H4) and major fatty acid iso-C16 : 0] supported the affiliation of strain Gsoil 616T to the genus Nocardioides. However, the results of physiological and biochemical tests allowed phenotypic differentiation of the isolate from other Nocardioides species. Therefore, strain Gsoil 616T represented a novel species within the genus Nocardioides, for which the name Nocardioides panacihumi sp. nov. is proposed. The type strain is Gsoil 616T (=KCTC 19187T =DSM 18660T).

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