Microflora of Meloidogyne egg masses: species composition, population density and effect on the biocontrol agent Verticillium chlamydosporium (Goddard)

Nematology ◽  
2001 ◽  
Vol 3 (8) ◽  
pp. 729-734 ◽  
Author(s):  
C.J.(Hans) Kok ◽  
Artemis Papert ◽  
C.B.(Chula) Bok-A-Bin
Keyword(s):  
Bacterial Population ◽  
Biocontrol Agent ◽  
Bacterial Species ◽  
Antagonistic Activity ◽  
Parasitic Fungus ◽  
Egg Mass ◽  
Egg Masses ◽  
Soil Suppressiveness ◽  
Verticillium Chlamydosporium

AbstractEgg masses of Meloidogyne fallax from tomato and potato growing in soil from a nematode suppressive and a nonsuppressive field sustained bacterial population densities two to three orders of magnitude higher than those of the rhizosphere soil. BIOLOG metabolic profiling identified 16 bacterial species from egg masses. Results further indicated 20 species not listed in the BIOLOG database. 122 isolates of bacteria and 19 isolates of fungi from M. fallax or M. hapla were tested for in vitro antagonism against the nematode egg parasitic fungus Verticillium chlamydosporium: 23% of the bacteria and 74% of the fungi showed antagonistic activity. Pseudomonads showed an overall stronger antagonistic activity than the other bacteria. Our conclusions are that Meloidogyne egg masses are a densely populated microbial niche and that their microflora may well be an important factor in determining the success of nematode antagonists. However, we could not find a relationship between the egg mass microflora and differences in soil suppressiveness between the sample sites.

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.

Dominant symbiotic bacteria associated with wild medfly populations reveal a bacteriocin-like killing phenotype: a ‘cold-case’ study

2019 ◽  
Vol 110 (4) ◽  
pp. 457-462
Author(s):  
Silvia Ciolfi ◽  
Laura Marri
Keyword(s):  
Bacterial Species ◽  
Klebsiella Oxytoca ◽  
Pcr Amplification ◽  
Fruit Trees ◽  
Antagonistic Activity ◽  
Culture Collection ◽  
Symbiotic Bacteria ◽  
Bacterial Populations

AbstractThe gut of the agricultural pest Ceratitis capitata hosts a varied community of bacteria, mainly Enterobacteriaceae, that were implicated in several processes that increase the fitness of the insect. In this study, we investigated the antagonistic activity in vitro of Klebsiella oxytoca strains isolated in the 1990s from the alimentary tract of wild medflies collected from different varieties of fruit trees at diverse localities. Assays were carried out against reference strains (representative of Gram-negative and -positive bacterial species) of the American Type Culture Collection (ATCC). Eight Klebsiella, out of 11, expressed a killing activity against Escherichia coli ATCC 23739, and Enterobacter cloacae ATCC 13047; among the eight strains, at least one showed activity against Salmonella typhimurium ATCC 23853. Genomic DNA derived from all Klebsiella strains was then subjected to PCR amplification using specific primer pairs designed from each of the four bacteriocin (KlebB, C, D, CCL) sequences found so far in Klebsiella. KlebD primer pairs were the only to produce a single product for all strains expressing the killing phenotype in vitro. One of the amplicons was cloned and sequenced; the DNA sequence shows 93% identity with a plasmid-carried colicin-D gene of a strain of Klebsiella michiganensis, and 86% identity with the sequence encoding for the klebicin D activity protein in K. oxytoca. Our work provides the first evidence that dominant symbiotic bacteria associated with wild medfly populations express a killing phenotype that may mediate inter and intraspecies competition among bacterial populations in the insect gut in vivo.

scholarly journals In Vitro Inhibition of Fungal Antagonists on Fusarium sp., the Disease Causative Agent on Dragon Fruit Plant (Hylocereus undatus (Haw.) Britton & Rose)

2018 ◽  
Vol 5 (2) ◽  
pp. 224
Author(s):  
Dewa Ayu Andriastini ◽  
Yan Ramona ◽  
Meitini Wahyuni Proborini
Keyword(s):  
Causative Agent ◽  
Biocontrol Agent ◽  
Antagonistic Activity ◽  
Assay Method ◽  
In Vitro Growth ◽  
Dragon Fruit ◽  
Fusarium Sp ◽  
In Vitro Inhibition ◽  
Hylocereus Undatus

A research on in vitro inhibition of fungal antagonists, isolated from dragon fruit plantation in Sembung village, Bali, on Fusarium sp. (the disease causative agent of dragon fruit plant) was conducted with the main objective to investigate the effectiveness of these fungal antagonists to inhibit the in vitro growth of the pathogen. Dual assay method was applied in this experiment. The results showed that three potential fungal antagonists were successfully isolated in this research and they were identified as Trichoderma harzianum, Aspergillus niger, dan Paecilomyces lilacinus. All these fungal antagonists showed antagonistic activity against Fusarium sp. which was statistically significant (p<0.05) when compared to control. This indicated that all antagonist isolates were potential to be developed as biocontrol agent candidates.

scholarly journals Investigating the in vitro and in vivo nematicidal performance of structurally related macrolides against the root-knot nematode, Meloidogyne incognita

2019 ◽  
Vol 12 (1) ◽  
pp. 24-37
Author(s):  
M.A. Radwan ◽  
A.S.A. Saad ◽  
H.A. Mesbah ◽  
H.S. Ibrahim ◽  
M.S. Khalil
Keyword(s):  
Meloidogyne Incognita ◽  
Root Length ◽  
Egg Mass ◽  
Root Knot Nematode ◽  
Egg Hatching ◽  
Shoot Height ◽  
Egg Masses ◽  
New Family

Summary Avermectins and spinosyns are structurally related natural products of microbial origin and belong to a new family of macrolides which are active against a vast array of invertebrate pests. In the present study, the effects of four members of macrolides; abamectin (ABM), emamectin benzoate (EMB), spinosad (SPI) and spinetoram (SPIT), on Meloidogyne incognita were investigated under in vitro and in vivo conditions. All compounds reduced egg hatching and led to high mortality of the nematode second-stage juveniles (J2). ABM showed the maximum rate of egg hatching inhibition and J2 mortality while SPIT recorded the minimum. All treatments reduced the number of galls, egg masses, eggs/egg mass in roots and J2 in the soil when compared to the control. Based on the 10 folds of the 24 h-LC50 values of J2 mortality in vitro, EMB and ABM exhibited higher percent reduction in galls (79.68 and 71.45%), egg masses (75.19 and 70.54%), eggs/egg mass (60.49 and 40.91%) and J2 in the soil (90.31 and 86.54%), respectively, compared to SPI and SPIT. Significant increase in tomato shoot height occurred in all biopesticides (10 folds) and SPIT (20 folds). SPI at 10 folds of the 24 h-LC50 values of J2 mortality in vitro, significantly increased root length while ABM at 50 folds and SPIT at 20 folds decreased root length by 5.15% and 5.88%, respectively, compared to the untreated inoculated plants. In all treatments, the dry shoot and root weights increased, compared to the untreated control. Our findings suggest that these macrolides have the ability to regulate nematode population densities and may be an alternative to classical nematicides.

scholarly journals Cladobotryum mycophilum as Potential Biocontrol Agent

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 891
Author(s):  
Mila Santos ◽  
Fernando Diánez ◽  
Alejandro Moreno-Gavíra ◽  
Brenda Sánchez-Montesinos ◽  
Francisco J. Gea
Keyword(s):  
Biological Control ◽  
Fusarium Oxysporum ◽  
Biocontrol Agent ◽  
Biological Control Agent ◽  
Control Agent ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Dual Culture ◽  
Potential Biocontrol Agent

A study was conducted to explore the efficacy of potential biocontrol agent Cladobotryum mycophilum against different phytopathogenic fungi. The growth rates of 24 isolates of C. mycophilum were determined, and their antagonistic activity was analysed in vitro and in vivo against Botrytis cinerea, Fusarium oxysporum f. sp. radicis-lycopersici, Fusarium oxysporum f.sp. cucumerinum, Fusarium solani, Phytophthora parasitica, Phytophthora capsici, Pythium aphanidermatum and Mycosphaerella melonis. Most isolates grow rapidly, reaching the opposite end of the Petri dish within 72–96 h. Under dual-culture assays, C. mycophilum showed antagonistic activity in vitro against all phytopathogenic fungi tested, with mycelial growth inhibition ranging from 30 to 90% against all the different phytopathogens tested. Similarly, of all the selected isolates, CL60A, CL17A and CL18A significantly (p < 0.05) reduced the disease incidence and severity in the plant assays compared to the controls for the different pathosystems studied. Based on these results, we conclude that C. mycophilum can be considered as a potential biological control agent in agriculture. This is the first study of Cladobotryum mycophilum as a biological control agent for different diseases caused by highly relevant phytopathogens in horticulture.

Potato-associated bacteria and their antagonistic potential towards plant-pathogenic fungi and the plant-parasitic nematodeMeloidogyne incognita(Kofoid & White) Chitwood

2002 ◽  
Vol 48 (9) ◽  
pp. 772-786 ◽  
Author(s):  
Annette Krechel ◽  
Annekathrin Faupel ◽  
Johannes Hallmann ◽  
Andreas Ulrich ◽  
Gabriele Berg
Keyword(s):  
Fungal Pathogens ◽  
Bacterial Species ◽  
Pathogenic Fungi ◽  
Antagonistic Activity ◽  
Polymorphism Analysis ◽  
Culturable Bacteria ◽  
Streptomyces Species ◽  
Associated Bacteria ◽  
Antagonistic Potential

To study the effect of microenvironments on potato-associated bacteria, the abundance and diversity of bacteria isolated from the rhizosphere, phyllosphere, endorhiza, and endosphere of field grown potato was analyzed. Culturable bacteria were obtained after plating on R2A medium. The endophytic populations averaged 103and 105CFU/g (fresh wt.) for the endosphere and endorhiza, respectively, which were lower than those for the ectophytic microenvironments, with 105and 107CFU/g (fresh wt.) for the phyllosphere and rhizosphere, respectively. The composition and richness of bacterial species was microenvironment-dependent. The occurrence and diversity of potato-associated bacteria was additionally monitored by a cultivation-independent approach using terminal restriction fragment length polymorphism analysis of 16S rDNA. The patterns obtained revealed a high heterogeneity of community composition and suggested the existence of microenvironment-specific communities. In an approach to measure the antagonistic potential of potato-associated bacteria, a total of 440 bacteria was screened by dual testing for in vitro antagonism towards the soilborne pathogens Verticillium dahliae and Rhizoctonia solani. The proportion of isolates with antagonistic activity was highest for the rhizosphere (10%), followed by the endorhiza (9%), phyllosphere (6%), and endosphere (5%). All 33 fungal antagonists were characterized by testing their in vitro antagonistic mechanisms, including their glucanolytic, chitinolytic, pectinolytic, cellulolytic, and proteolytic activity, and by their BOX-PCR fingerprints. In addition, they were screened for their biocontrol activity against Meloidogyne incognita. Overall, nine isolates belonging to Pseudomonas and Streptomyces species were found to control both fungal pathogens and M. incognita and were therefore considered as promising biological control agents. Key words: biocontrol, antagonistic potential, plant-associated bacteria.

scholarly journals In-Vitro Antagonistic Activity of Plant Extract on Fusarium Species

2019 ◽  
Vol 18 (4) ◽  
pp. 53-62
Author(s):  
P Asiya ◽  
PR Sreeraj ◽  
Joseph John ◽  
PB Ramya
Keyword(s):  
Fungal Pathogen ◽  
Biocontrol Agent ◽  
Plant Protection ◽  
Fusarium Species ◽  
Antagonistic Activity ◽  
Agricultural System ◽  
Maximum Inhibition ◽  
Fusarium Sp ◽  
Poison Food Technique

Plant protection is an important area which needs attention since most of the hazardous inputs added into the agricultural system are in the form of plant protection chemicals. Botanicals possess a variety of promising properties which make it a better biocontrol agent. The objectives of the present study were to isolate Fusarium sp. from soil and to check the effect of botanicals against this fungal pathogen in-vitro. The antagonistic activity of botanicals was studied by co-inoculation with the Fusarium sp. isolated from rhizosphere soil. In poison food technique, the botanicals in different concentration, showed decrease in the growth of the fungal pathogen. Maximum inhibition was observed in 10% Azadiracta sp. with 64% inhibition followed by 5% Azadiracta sp. with 57.8%

scholarly journals Chitinolytic and Antagonistic Activity of Streptomyces Isolated from Fadama Soil against Phytopathogenic Fungi

2021 ◽  
Vol 32 (3) ◽  
pp. 25-38
Author(s):  
Aminu Argungu Umar ◽  
Aminu Bandam Hussaini ◽  
Jibril Yahayya ◽  
Ibrahim Sani ◽  
Habiba Aminu
Keyword(s):  
Antifungal Agents ◽  
Biocontrol Agent ◽  
Specific Activity ◽  
Extracellular Enzyme ◽  
Chitinase Activity ◽  
Phytopathogenic Fungi ◽  
Antagonistic Activity ◽  
Different Temperatures ◽  
Chitinase Production

Chitinases which degrade chitin have attracted attention as biological antifungal agents. The purpose of this study is to isolate Streptomyces from Fadama soil and assess its chitinolytic and antagonist potential against phytopathogenic fungi for application as biocontrol agent. Streptomyces were isolated from Fadama soil. The selected isolate CT02 exhibited chitinolytic characteristics. Chitinase production was performed under different temperatures, pH and varying incubation period. The highest chitinase production by CT02 isolate was observed after five days of cultivation. The highest chitinase activity was observed at 35°C and pH 7. The crude extracellular enzyme exhibited a specific activity of 4.20 U/μg whereas partially purified extracellular enzyme exhibited a specific activity of 6.19 U/μg with purification fold of 1.47. The selected isolate CT02 and its extracellular crude chitinase showed in vitro antifungal antagonist potential by inhibiting the growth of Aspergillus niger and Aspergillus oryzae. This indicates that Streptomyces derived chitinases are potential biocontrol agents against phytopathogenic fungi.

scholarly journals FUNCTIONAL AND MOLECULAR CHARACTERIZATION OF WHEAT RHIZOSPHERE BACTERIA AND THEIR ANTAGONISTIC ACTIVITY AGAINST WHEAT FOLIAR BLIGHT PATHOGENS

2020 ◽  
Vol 8 (5) ◽  
pp. 605-620
Author(s):  
Vandana Jaggi ◽  
◽  
Samiksha Joshi ◽  
Hemant Dasila ◽  
Navneet Pareek ◽  
...  
Keyword(s):  
Population Density ◽  
Bacterial Population ◽  
Uttar Pradesh ◽  
Bipolaris Sorokiniana ◽  
Antagonistic Activity ◽  
Soil Samples ◽  
Pgp Traits ◽  
Foliar Blight ◽  
Blight Disease

The current study aimed to explore the wheat rhizospheric bacterial community for in vitro plant growth-promoting (PGP) traits and antagonistic activity against foliar blight disease of wheat caused by Alternaria triticina and Bipolaris sorokiniana. The soil samples from the wheat fields across four Indian states namely Uttarakhand (2 sites), Uttar Pradesh, Madhya Pradesh, and Maharashtra were analyzed for their physicochemical properties, enzymatic activities, and bacterial population density (CFU g-1). Amongst the tested soil samples, field soil from Uttar Pradesh has the highest bacterial population density (2.5x107 CFU g 1) while the Uttarakhand (Almora) soil has the lowest (8.5x 105 CFU g 1). A total of 45 bacterial isolates recovered from all the sites were morphologically identified and screened for in-vitro solubilization of phosphate & zinc, production of ammonia, siderophore, chitinase, protease, cellulase, amylase, lipase, and antagonistic activity. All isolates were found positive for one or more tested functional traits. Amongst 45 isolates, six showed >50% inhibition of Alternaria triticina and Bipolaris sorokiniana mycelium, and three isolates P10, UP11 & MH13 exhibited antagonistic activity against both the tested phytopathogens. Through 16S rDNA sequencing six putative biocontrol isolates, P10, UP11, MH13, MP17, MH12, and MP14 were identified as Bacillus methylotrophicus (MN099430.1), Bacillus subtilis (MN099431.1), Bacillus sp. (MN099432.1), Streptomyces sp. (MN099435.1), Lysinibacillus sp. (MN099433.1), and Staphylococcus epidermidis (MN099434.1). The selected wheat rhizobacteria exhibited PGP traits and biocontrol potential hence, may serve as putative biocontrol agents, for the management of foliar blight disease of wheat.

scholarly journals THE IDENTIFICATION, PRODUCTION AND CHARACTERIZATION OF NATTOKINASE, BACTERIOCIN FROM BACTERIAL SPECIES

2019 ◽  
Vol 2 (4) ◽  
pp. 91
Author(s):  
Lal Krishna
Keyword(s):  
Enzyme Activity ◽  
Bacillus Subtilis ◽  
Pathogenic Bacteria ◽  
Blood Clot ◽  
Bacterial Species ◽  
Antagonistic Activity ◽  
Bacterial Strains ◽  
Wide Range

The study was aimed at identification, production and characterization of nattokinase, bacteriocin from bacterial species. Nattokinase and bacteriocins finds a wide range of applications in Pharmaceutical industry, health care and medicine. Nattokinase is a highly active fibrinolytic enzyme secreted by Bacillus subtilis and bacteriocins are proteinaceous toxins produced by Lactobacillus to inhibit the growth of closely related bacterial strains. Bacillus subtilis and Lactobacillus isolates shown positive results to microscopic, biochemical analysis.  The nattokinase and bacteriocins were produced by optimizing the media. The enzymes were purified by ammonium sulfate precipitation and HPLC. The enzyme activity for nattokinase was found at 7 mg/ml, pH 8.0 and temperature 48 ºC and the enzyme activity for bacteriocin was found at 3.9 mg/ml, pH 6.5 and temperature 30 °C. Bacteriocins from Lactobacillus showed good antagonistic activity against pathogenic bacteria. Nattokinase from Bacillus subtilis played a significant role in thrombolytic and anti-coagulation at in vitro. The results indicated that the pure enzyme has a potential in dissolving blood clot.

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