Antifungal activity of extracts from endophytic fungi associated with Smallanthus maintained in vitro as autotrophic cultures and as pot plants in the greenhouse

2012 ◽  
Vol 58 (10) ◽  
pp. 1202-1211 ◽  
Author(s):  
Luiz H. Rosa ◽  
Nurhayat Tabanca ◽  
Natascha Techen ◽  
Zhiqiang Pan ◽  
David E. Wedge ◽  
...  

The endophytic fungal assemblages associated with Smallanthus sonchifolius (Poepp.) H. Rob. and Smallanthus uvedalius (L.) Mack. ex Small growing in vitro autotrophic cultures and in the greenhouse were identified and evaluated for their ability to produce bioactive compounds. A total of 25 isolates were recovered that were genetically closely related to species of the genera Bionectria , Cladosporium , Colletotrichum , Fusarium , Gibberella , Hypocrea , Lecythophora , Nigrospora , Plectosphaerella , and Trichoderma . The endophytic assemblages of S. sonchifolius presented a greater diversity than the group isolated from S. uvedalius and demonstrated the presence of dominant generalist fungi. Extracts of all fungi were screened against the fungal plant pathogens. Ten extracts (41.6%) displayed antifungal activities; some of them had a broad antifungal activity. The phylotypes Lecythophora sp. 1, Lecythophora sp. 2, and Fusarium oxysporum were isolated from in vitro autotrophic cultures and displayed antifungal activity. The presence of bioactive endophytic fungi within S. sonchifolius and S. uvedalius suggests an ecological advantage against pathogenic attacks. This study revealed reduced numbers of endophytes in association with both Smallanthus species in controlled cultivation conditions compared with the endophytic communities of hosts collected in the wild environments. Even as reduced endophytic communities, these fungi continue to provide chemical protection for the host.

1996 ◽  
Vol 42 (7) ◽  
pp. 690-700 ◽  
Author(s):  
Paige E. Axelrood ◽  
Alison M. Clarke ◽  
Reed Radley ◽  
S. Janet V. Zemcov

A microbial culture collection composed of 1820 bacterial strains, including 298 actinomycete strains, was established from the roots of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seedlings harvested from conifer nurseries and forest sites. Two hundred and thirty-four strains inhibited the growth of Fusarium, Cylindrocarpon, and (or) Pythium spp. in in vitro assays. A significantly greater proportion of bacterial strains from actinomycete genera exhibited antifungal properties compared with bacterial strains from nonactinomycete genera. Eighty-nine percent of identified inhibitory strains were Streptomyces, Streptoverticillium, Bacillus, Pseudomonas, or Burkholderia species. The actinomycete species were isolated almost exclusively from forest seedlings. Recovery of inhibitory strains representing 29 microbial species was enhanced using a variety of methods to isolate microorganisms from the roots of seedlings from nursery and forest sites. Bacterial strains (including actinomycete strains) with antifungal activity were tested for in vitro growth inhibition of six clinical human bacterial pathogens (Enterococcus faecalis, Staphylococcus aureus, Klebsiella pneumoniae, Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa). Forty-eight percent of the tested strains inhibited one or more human pathogens. Inhibitory activity towards fungal and bacterial pathogens was strain specific, not species specific, and many inhibitory strains exhibited broad-spectrum activity. Strains with antifungal activity against several conifer root pathogens were also more likely to inhibit multiple species of clinical bacterial pathogens.Key words: in vitro, antimicrobial, conifer rhizosphere.


PeerJ ◽  
2019 ◽  
Vol 7 ◽  
pp. e6905 ◽  
Author(s):  
Elena Maria Colombo ◽  
Cristina Pizzatti ◽  
Andrea Kunova ◽  
Claudio Gardana ◽  
Marco Saracchi ◽  
...  

Biocontrol microorganisms are emerging as an effective alternative to pesticides. Ideally, biocontrol agents (BCAs) for the control of fungal plant pathogens should be selected by an in vitro method that is high-throughput and is predictive of in planta efficacy, possibly considering environmental factors, and the natural diversity of the pathogen. The purpose of our study was (1) to assess the effects ofFusariumstrain diversity (N= 5) and culture media (N= 6) on the identification of biological control activity ofStreptomycesstrains (N= 20) againstFusariumpathogens of wheat in vitro and (2) to verify the ability of our in vitro screening methods to simulate the activity in planta. Our results indicate that culture media,Fusariumstrain diversity, and their interactions affect the results of an in vitro selection by dual culture assay. The results obtained on the wheat-based culture media resulted in the highest correlation score (r= 0.5) with the in planta root rot (RR) inhibition, suggesting that this in vitro method was the best predictor of in planta performance of streptomycetes against Fusarium RR of wheat assessed as extension of the necrosis on the root. Contrarily, none of the in vitro plate assays using the media tested could appropriately predict the activity of the streptomycetes against Fusarium foot rot symptoms estimated as the necrosis at the crown level. Considering overall data of correlation, the activity in planta cannot be effectively predicted by dual culture plate studies, therefore improved in vitro methods are needed to better mimic the activity of biocontrol strains in natural conditions. This work contributes to setting up laboratory standards for preliminary screening assays ofStreptomycesBCAs against fungal pathogens.


2019 ◽  
Vol 109 (3) ◽  
pp. 402-408 ◽  
Author(s):  
Andrew E. Sathoff ◽  
Siva Velivelli ◽  
Dilip M. Shah ◽  
Deborah A. Samac

Plant defensins are small, cysteine-rich antimicrobial peptides. These peptides have previously been shown to primarily inhibit the growth of fungal plant pathogens. Plant defensins have a γ-core motif, defined as GXCX3-9C, which is required for their antifungal activity. To evaluate plant defensins as a potential control for a problematic agricultural disease (alfalfa crown rot), short, chemically synthesized peptides containing γ-core motif sequences were screened for activity against numerous crown rot pathogens. These peptides showed both antifungal and, surprisingly, antibacterial activity. Core motif peptides from Medicago truncatula defensins (MtDef4 and MtDef5) displayed high activity against both plant and human bacterial pathogens in vitro. Full-length defensins had higher antimicrobial activity compared with the peptides containing their predictive γ-core motifs. These results show the future promise for controlling a wide array of economically important fungal and bacterial plant pathogens through the transgenic expression of a plant defensin. They also suggest that plant defensins may be an untapped reservoir for development of therapeutic compounds for combating human and animal pathogens.


Antibiotics ◽  
2019 ◽  
Vol 8 (4) ◽  
pp. 231
Author(s):  
Xiao-Yu Song ◽  
Huihua Wang ◽  
Fei Ren ◽  
Kaiying Wang ◽  
Guiming Dou ◽  
...  

Volatile organic compounds (VOCs) from endophytic fungi are becoming a potential antibiotic resource. The inhibitive effects of VOCs produced by an endophytic fungus in Leucaena leucocephala were investigated on plant pathogens in this study. Using standard morphological methods and multigene phylogeny, the fungus was identified as Diaporthe apiculatum strain FPYF 3052. Utilizing a two- compartment Petri plate bioassay method, the VOCs from this fungus showed bioactivity ranging from 23.8% to 66.7% inhibition on eight plant pathogens within 24 hours. The SPME-GC/MS technique identified fifteen volatile compounds with dominant terpenoids γ-terpinene (39.8%), α-terpinene (17.2%), and (-)-4-terpineol (8.4%) from the VOCs. Commercial α-terpinene, γ-terpinene, and (-)-4-terpineol demonstrated inhibition on the tested pathogens at concentrations from 0.2 to 1.0 µl/ml within 72 h in the bioassay system. The inhibition rates were from 28% to 100% percent using 1.0 µl/ml within 48 h. (-)-4-Terpineol was the most active of the terpenoids causing up to 100% inhibition. The data illustrate that these monoterpenes play an important role in the inhibitive bioactivity of the VOCs of D. apiculatum FPYF 3052. Most importantly, (-)-4-terpineol is now for the first time, reported to have capability of strong antifungal activity and could be developed as an antibiotic substance.


2020 ◽  
Vol 13 (2) ◽  
pp. 247-258 ◽  
Author(s):  
A.D. Gong ◽  
G.J. Sun ◽  
Z.Y. Zhao ◽  
Y.C. Liao ◽  
J.B. Zhang

Controlling proliferation and aflatoxin production by Aspergillus flavus is a pressing challenge for global food safety and security. Marine bacterium Staphylococcus saprophyticus strain L-38 showed excellent antifungal activity toward A. flavus in vitro and in vivo. In sealed, non-contact confrontation assays, L-38 completely inhibited conidial germination and mycelial growth of A. flavus through the production of volatile organic compounds (VOCs). Gas chromatography-mass spectrometry identified 3,3-dimethyl-1,2-epoxybutane (3-DE) as the most abundant VOC (32.61% of total peak area, 78% matching). Exposure of A. flavus cultures to synthetic 3-DE similarly demonstrated strong inhibition of growth. Moreover, culture of L-38 in a sealed chamber with maize or peanuts artificially inoculated with A. flavus, at high water activity, resulted in significant inhibition of A. flavus germination and aflatoxin biosynthesis. Scanning electron microscopy of these samples revealed severe damage to conidial cells and hyphae compared to samples not exposed to L-38. L-38 also showed broad and effective antifungal activity toward eight other phytopathogenic fungi including Aspergillus niger, Fusarium verticillioides, Fusarium graminearum, Sclerotinia sclerotiorum, Rhizoctonia solani, Alternaria alternata, Monilinia fructicola, and Botrytis cinerea. This work introduces S. saprophyticus L-38 as a potential biocontrol agent and demonstrates the efficacy of the volatile 3-DE in the control of A. flavus and other destructive plant pathogens for post-harvest food safety.


2010 ◽  
Vol 48 (1) ◽  
pp. 1-6 ◽  
Author(s):  
Hai-Yan Li ◽  
Chun-An Zhao ◽  
Chen-Jian Liu ◽  
Xiao-Fei Xu

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11242
Author(s):  
Sarunpron Khruengsai ◽  
Patcharee Pripdeevech ◽  
Chutima Tanapichatsakul ◽  
Chanin Srisuwannapa ◽  
Priya Esilda D’Souza ◽  
...  

Fungal endophytes are microorganisms living symbiotically with a host plant. They can produce volatile organic compounds (VOCs) that have antimicrobial activity. This study aimed to isolate endophytic fungi from Barleria prionitis plants grown in Thailand and to investigate the antifungal properties of their VOCs against Colletotrichum acutatum, a causal agent of anthracnose disease on post-harvest strawberry fruits. A total of 34 endophytic fungi were isolated from leaves of B. prionitis. The VOCs produced from each individual isolate were screened for their antifungal activity against C. acutatum using a dual-culture plate method. From this in vitro screening experiment, the VOCs produced by the endophytic isolate BP11 were found to have the highest inhibition percentage (80.3%) against the mycelial growth of C. acutatum. The endophytic isolate BP11 was molecularly identified as Daldinia eschscholtzii MFLUCC 19-0493. This strain was then selected for an in vivo experiment. Results from the in vivo experiment indicated that the VOCs produced by D. eschscholtzii MFLUCC 19-0493 were able to inhibit infections by C. acutatum on organic fresh strawberry fruits with an average inhibition percentage of 72.4%. The quality of the pathogen-inoculated strawberry fruits treated with VOCs produced by D. eschscholtzii MFLUCC 19-0493 was evaluated. Their fruit firmness, total soluble solids, and pH were found to be similar to the untreated strawberry fruits. Solid phase microextraction-gas chromatographic-mass spectrometric analysis of the VOCs produced by D. eschscholtzii MFLUCC 19-0493 led to the detection and identification of 60 compounds. The major compounds were elemicin (23.8%), benzaldehyde dimethyl acetal (8.5%), ethyl sorbate (6.8%), methyl geranate (6.5%), trans-sabinene hydrate (5.4%), and 3,5-dimethyl-4-heptanone (5.1%). Each major compound was tested for its antifungal activity against C. acutatum using the in vitro assay. While all these selected VOCs showed varying degrees of antifungal activity, elemicin was found to possess the strongest antifungal activity. This work suggests that D. eschscholtzii MFLUCC 19-0493 could be a promising natural preservative for controlling C. acutatum associated anthracnose disease in strawberry fruits during the post-harvest period.


Author(s):  
Iván De-la-Cruz-Chacón ◽  
Nora Yazmin López-Fernández ◽  
Christian Anabí Riley-Saldaña ◽  
Marisol Castro Moreno ◽  
Alma Rosa González-Esquinca

Background and Aims: The phytochemistry study of Annonaceae has intensified in the last decades due to the discovery of secondary metabolites with antimicrobial activities. The inhibitory activities of extracts and compounds from these species for phytopathogens are less known. The antifungal activity of Sapranthus microcarpus was determined in vitro against six fungal pathogens of important crops.Methods: Hexane, methanol, and alkaloid extracts of the leaves and root and stem bark of S. microcarpus were evaluated to determine whether they could inhibit the mycelial growth of the phytopathogens. The combined activity of the most active extracts for each phytopathogen was also determined. The alkaloid liriodenine was isolated and identified as an antifungal principle.Key results: All extracts inhibited the growth of the six phytopathogens to some extent. The root bark alkaloid extract showed the highest activity. Fusarium oxysporum f. sp. lycopersici and Curvularia lunata were the most sensitive phytopathogens. Liriodenine was active against all the plant pathogens (minimum inhibitory concentrations of 125-500 nmol ml-1).Conclusions: Sapranthus microcarpus is a native natural resource with great phytochemical potential.


2012 ◽  
Vol 59 (2) ◽  
pp. 51-58 ◽  
Author(s):  
Alicja Saniewska ◽  
Anna Jarecka ◽  
Zbigniew Biały ◽  
Marian Jurzysta

Antifungal activity of total saponins originated from roots of <i>Medicago hybrida</i> (Pourret) Trautv. were evaluated <i>in vitro</i> against six pathogenic fungi and eight individual major saponin glycosides were tested against one of the most susceptible fungi. The total saponins showed fungitoxic effect at all investigated concentrations (0.01%, 0.05% and 0.1%) but their potency was different for individual fungi. The highest saponin concentration (0.1%) was the most effective and the inhibition of <i>Fusarium oxysporum</i> f. sp. <i>callistephi</i>, <i>Botrytis cinerea</i>, <i>Botrytis tulipae</i>, <i>Phoma narcissi</i>, <i>Fusarium oxysporum</i> f. sp. <i>narcissi</i> was 84.4%, 69.9%, 68.6%, 57.2%, 55.0%, respectively. While <i>Fusarium oxysporum</i> Schlecht., a pathogen of <i>Muscari armeniacum</i>, was inhibited by 9.5% only. Eight major saponin glycosides isolated from the total saponins of <i>M. hybrida</i> roots were tested against the mycelium growth of <i>Botrytis tulipae</i>. The mycelium growth of the pathogen was greatly inhibited by hederagenin 3-O-<i>β</i>-D-glucopyranoside and medicagenic acid 3-O-<i>β</i>-D-glucopyranoside. Medicagenic acid 3-O-<i>β</i>-D-glucuronopyranosyl-28-O-<i>β</i>-D-glucopyranoside and oleanolic acid 3-O-[<i>β</i>-D-glucuronopyranosyl(1→2)-<i>α</i>-L-galactopyranosyl]-28-O-<i>β</i>-D-glucopyranoside showed low fungitoxic activity. Medicagenic acid 3-O-a-D-glucopyranosyl- 28-O-β-D-glucopyranoside, hederagenin 3-O-[α-L- hamnopyranosyl(1→2)-β-D-glucopyranosyl(1→2)-β-D-glucopyranosyl]- 28-O-α-D-glucopyranoside and hederagenin 3-O-<i>β</i>-D-glucuronopyranosyl-28-O-<i>β</i>-D- lucopyranoside did not limit or only slightly inhibited growth of the tested pathogen. While 2<i>β</i>, 3<i>β</i>-dihydroxyolean-12 ene-23-al-28-oic acid 3-O-<i>β</i>-D-glucuronopyranosyl-28-O-<i>β</i>-D-glucopyranoside slightly stimulated mycelium growth of <i>B. tulipae</i>.


2020 ◽  
Vol 13 (6) ◽  
pp. 1
Author(s):  
D. C. S. Lemos ◽  
G. R. Sousa ◽  
A. D. V. Souza ◽  
J. B. A. França ◽  
M. R. Rosa ◽  
...  

The Cerrado has wide plant diversity, including orchids. These plants need symbiosis with fungi for their germination to occur in the wild. In vitro or asbiotic cultivation is an alternative for the production of seedlings of this species. This diversity of orchids makes it much appreciated as pot plants, landscaping, with high commercial value. The objective of this work was to carry out the study for the development of a protocol for the germination and in vitro development of orchids. The experiment was carried out at the LABIOTEC Biotechnology Laboratory of the Federal Institute Goiano Campus Urutaí-GO. Catasetum sp native capsules from Goiás State, containing mature seeds were collected and disinfected in 50% sodium hypochlorite solution for 30 minutes and in laminar flow were washed four times in distilled and autoclaved water. They were then seeded in vitro in 258 mL glass vials containing 30 mL of MS medium enriched with vitamins and 0.0 Tryptone; 1.0; 2.0 and 3.0 g L-1. The pH of the medium was adjusted to 5.2 ± 0.1. The average time for germination and development of the protocorms varied from 3 to 7 days after sowing for the species under study. The dosage of 2.0 g L-1 is efficient for the development and maintenance of in vitro Catasetum protocorms up to 333 days. There was no development of shoot of Catasetum seedlings in any of the evaluated treatments. It was observed that the 3.0 g L-1 Tryptone dosage presented higher rates of fungal and bacterial contamination and oxidation


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