Isolation and selection of bacteria and yeasts antagonistic to preharvest infection of avocado by Colletotrichum gloeosporioides

1995 ◽  
Vol 46 (5) ◽  
pp. 985 ◽  
Author(s):  
AM Stirling ◽  
LM Coates ◽  
KG Pegg ◽  
AC Hayward
Keyword(s):  
Spore Germination ◽  
Colletotrichum Gloeosporioides ◽  
Lesion Size ◽  
Antibiotic Resistant ◽  
Avocado Fruit ◽  
Bacillus Spp ◽  
Colonization Potential ◽  
Aureobasidium Sp ◽  
Leaf Disks ◽  
Selection Of

Bacteria and yeasts were isolated from leaves, flowers and fruit of avocado trees that had not been sprayed with pesticides for several years. Of the 1050 microorganisms isolated, 37% inhibited mycelial growth of Colletotrichum gloeosporioides on potato dextrose agar. Many of these organisms also significantly reduced spore germination of the fungus on cellophane overlaying weak sugars agar and a greater proportion of yeasts than bacteria were more effective. Some bacteria and yeasts also reduced spore germination of the pathogen on avocado leaf disks. The predominant group of suppressive bacteria was Bacillus spp., and the antagonistic yeasts included Aureobasidium spp. and a variety of pink and white colony types. Antibiotic resistant isolates of Bacillus, carbendazim resistant isolates of two yeasts and an Aureobasidium sp. were sprayed on avocado leaves and survived for at least 2 months on the phylloplane. On the basis of performance in these tests, isolates with biocontrol and colonization potential were selected and tested for their capacity to provide disease control on fruit. In repeated tests, several bacteria and yeasts consistently reduced lesion development and lesion size on detached avocado fruit when applied prior to inoculating fruit with the pathogen.

scholarly journals Tetracycline-Resistant Bacteria Selected from Water and Zebrafish after Antibiotic Exposure

2021 ◽  
Vol 18 (6) ◽  
pp. 3218
Author(s):  
Ana Rita Almeida ◽  
Marta Tacão ◽  
Joana Soares ◽  
Inês Domingues ◽  
Isabel Henriques
Keyword(s):  
Statistical Significance ◽  
Recovery Period ◽  
Antibiotic Resistance Genes ◽  
Antibiotic Use ◽  
Resistant Bacteria ◽  
Antibiotic Resistant ◽  
Potential Impact ◽  
Susceptibility Profiles ◽  
Selection Of ◽  
Significant Mortality

The emergence of antibiotic-resistant pathogens due to worldwide antibiotic use is raising concern in several settings, including aquaculture. In this work, the selection of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs) was evaluated after exposure of zebrafish to oxytetracycline (OTC) for two months, followed by a recovery period. The selection of ARB in water and fish was determined using selective media. The abundance of tetA genes was estimated through qPCR. Higher prevalence of ARB was measured in all samples exposed to the antibiotic when compared to control samples, although statistical significance was only achieved five days after exposure. Isolates recovered from samples exposed to the antibiotic were affiliated with Pseudomonas and Stenotrophomonas. Various antibiotic susceptibility profiles were detected and 37% of the isolates displayed multidrug resistance (MDR). The selection of the tetA gene was confirmed by qPCR at the highest OTC concentration tested. Two MDR isolates, tested using zebrafish embryos, caused significant mortality, indicating a potential impact on fish health and survival. Overall, our work highlights the potential impact of antibiotic contamination in the selection of potential pathogenic ARB and ARGS.

Selection of Bacillus spp. with decontamination potential on multiple Fusarium mycotoxins

Food Control ◽  
2021 ◽  
pp. 108119
Author(s):  
Zahoor Ul Hassan ◽  
Roda Al Thani ◽  
Mohammed Alsafran ◽  
Quirico Migheli ◽  
Samir Jaoua
Keyword(s):  
Fusarium Mycotoxins ◽  
Bacillus Spp ◽  
Selection Of

Interactions between micro-organisms on skin

1980 ◽  
Vol 79 (1-3) ◽  
pp. 185-191
Author(s):  
W. C. Noble
Keyword(s):  
Skin Lesion ◽  
Secondary Metabolites ◽  
Bacterial Flora ◽  
Antibiotic Resistant ◽  
General Terms ◽  
Micro Organisms ◽  
Selection Of

SynopsisThe mechanisms of interaction are discussed in general terms; this is followed by a review of interaction which may occur in tinea paedis.The production of penicillin-like and other antibiotics by dermatophyte fungi in lesions of athletes foot may result in the selection of an antibiotic-resistant bacterial flora which, perhaps by production of antibiotic or other secondary metabolites, can reduce the viability of the fungi. The effect on the host is to bring about a change from a fungal skin lesion which is dry and scaly to a bacterial lesion which is macerated and malodorous.

scholarly journals Potential risks of antibiotic resistant bacteria and genes in bioremediation of petroleum hydrocarbon contaminated soils

2020 ◽  
Vol 22 (5) ◽  
pp. 1110-1124 ◽  
Author(s):  
Colin J. Cunningham ◽  
Maria S. Kuyukina ◽  
Irena B. Ivshina ◽  
Alexandr I. Konev ◽  
Tatyana A. Peshkur ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Petroleum Hydrocarbon ◽  
Resistant Bacteria ◽  
Careful Selection ◽  
Bacterial Strains ◽  
Antibiotic Resistant ◽  
Potential Risks ◽  
Selection Of

The problems associated with potential risks of antibiotic resistance spreading during bioremediation of oil-contaminated soil are discussed. Careful selection of bacterial strains and pretreatment of organic wastes used as fertilizers are suggested.

scholarly journals Metabolism of the Flavonoid Epicatechin by Laccase of Colletotrichum gloeosporioides and Its Effect on Pathogenicity on Avocado Fruits

2005 ◽  
Vol 95 (11) ◽  
pp. 1341-1348 ◽  
Author(s):  
R. Guetsky ◽  
I. Kobiler ◽  
X. Wang ◽  
N. Perlman ◽  
N. Gollop ◽  
...  
Keyword(s):  
Colletotrichum Gloeosporioides ◽  
Laccase Activity ◽  
Thioglycolic Acid ◽  
Culture Media ◽  
Antifungal Compounds ◽  
Symptom Development ◽  
Fungal Attack ◽  
Avocado Fruit ◽  
Laccase Enzyme ◽  
Unripe Fruits

During avocado fruit ripening, decreasing levels of the flavonoid epicatechin have been reported to modulate the metabolism of preformed antifungal compounds and the activation of quiescent Colletotrichum gloeosporioides infections. Epicatechin levels decreased as well when C. gloeosporioides was grown in the presence of epicatechin in culture. Extracts of laccase enzyme obtained from decayed tissue and culture media fully metabolized the epicatechin substrate within 4 and 20 h, respectively. Purified laccase protein from C. gloeosporioides showed an apparent MW of 60,000, an isoelectric point at pH 3.9, and maximal epicatechin degradation at pH 5.6. Inhibitors of fungal laccase such as EDTA and thioglycolic acid reduced C. gloeosporioides symptom development when applied to ripening susceptible fruits. Isolates of C. gloeosporioides with reduced laccase activity and no capability to metabolize epicatechin showed reduced pathogenicity on ripening fruits. On the contrary, Mexican isolates with increasing capabilities to metabolize epicatechin showed early symptoms of disease in unripe fruits. Transcript levels of cglac1, encoding C. gloeosporioides laccase, were enhanced during fungal development in the presence of epicatechin at pH 6.0, where avocado fruits are susceptible to fungal attack. But transcript increase was not detected at pH 5.0, where the fruit is resistant to fungal attack. The present results suggest that biotransformation of epicatechin by C. gloeosporioides in ripening fruits is followed by the decline of the preformed antifungal diene compound, resulting in the activation of quiescent infections.

Susceptibility of Fuerte avocado fruit at various stages of growth, to infection by anthracnose and stem end rot fungi

1978 ◽  
Vol 18 (90) ◽  
pp. 158 ◽  
Author(s):  
RA Peterson
Keyword(s):  
Field Experiments ◽  
Colletotrichum Gloeosporioides ◽  
Natural Infection ◽  
Persea Americana ◽  
Glomerella Cingulata ◽  
Stages Of Growth ◽  
Small Fruit ◽  
Avocado Fruit ◽  
Time Of Infection

In a series of field experiments, Fuerte avocado fruit (Persea americana) were susceptible to infection by Glomerella cingulata var. minor (Colletotrichum gloeosporioides var, minor) and Dothiorella aromatics, from set until harvest. Natural infection was detected from December to May and field inoculations demonstrated that small fruit in October were also susceptible. The time of infection varied with the season and was related to rainfall incidence. The significance of this finding is discussed.

scholarly journals Differential Activation of Ammonium Transporters During the Accumulation of Ammonia by Colletotrichum gloeosporioides and Its Effect on Appressoria Formation and Pathogenicity

2013 ◽  
Vol 26 (3) ◽  
pp. 345-355 ◽  
Author(s):  
Chen Shnaiderman ◽  
Itay Miyara ◽  
Ilana Kobiler ◽  
Amir Sherman ◽  
Dov Prusky
Keyword(s):  
Gene Disruption ◽  
Colletotrichum Gloeosporioides ◽  
Ammonium Transporter ◽  
Ammonium Transport ◽  
Wild Type ◽  
Ammonia Accumulation ◽  
Ammonium Transporters ◽  
Avocado Fruit ◽  
Appressoria Formation ◽  
Encoding Genes

Ammonium secreted by the post-harvest pathogen Colletotrichum gloeosporioides during host colonization accumulates in the host environment due to enhanced fungal nitrogen metabolism. Two types of ammonium transporter-encoding genes, AMET and MEP, are expressed during pathogenicity. Gene disruption of AMET, a gene modulating ammonia secretion, showed twofold reduced ammonia secretion and 45% less colonization on avocado fruit, suggesting a contribution to pathogenicity. MEPB, a gene modulating ammonium transport, is expressed by C. gloeosporioides during pathogenicity and starvation conditions in culture. Gene disruption of MEPB, the most highly expressed gene of the MEP family, resulted in twofold overexpression of MEPA and MEPC but reduced colonization, suggesting MEPB expression's contribution to pathogenicity. Analysis of internal and external ammonia accumulation by ΔmepB strains in mycelia and germinated spores showed rapid uptake and accumulation, and reduced secretion of ammonia in the mutant versus wild-type (WT) strains. Ammonia uptake by the WT germinating spores but not by the ΔmepB strain with compromised ammonium transport activated cAMP and transcription of PKA subunits PKAR and PKA2. ΔmepB mutants showed 75% less appressorium formation and colonization than the WT, which was partially restored by 10 mM exogenous ammonia. Thus, whereas both AMET and MEPB genes modulate ammonia secretion, only MEPB contributes to ammonia accumulation by mycelia and germinating spores that activate the cAMP pathways, inducing the morphogenetic processes contributing to C. gloeosporioides pathogenicity.

Sign in / Sign up

Export Citation Format

Share Document