37 research outputs found
Identification of a new strain of Actinomadura isolated from Saharan soil and partial characterization of its antifungal compounds
One promising strain Actinomadura sp. AC170, isolated from Algerian Saharan soil, with strong antifungal activity against pathogenic and toxinogenic fungi, was selected for further studies. The 16S rRNA results showed a distinct phylogenetic lineage from the other species within the Actinomadura genus. The production of antibiotic substances was investigated using GYEA solid medium. The butanolic extract contained four bioactive spots detected on thin layer chromatography plates. Among these antibiotics, a complex called 170A, which showed the more interesting antifungal activity, was selected and purified by reverse-phase HPLC. This complex is composed of four compounds. Ultraviolet-visible, infrared, mass and H nuclear magnetic resonance spectroscopy studies showed that these molecules contain an aromatic ring substituted by aliphatic chains. These compounds differ from the known antibiotics produced by Actinomadura species.Key words: Actinomadura, taxonomy, antifungal compounds, Saharan soil
Taxonomy and chemical characterization of new antibiotics produced by Saccharothrix SA198 isolated from a Saharan soil
Actinomycete strain SA198, isolated from a Saharan soil sample of Algeria, exhibited antimicrobial activity
against Gram-positive and Gram-negative bacteria, and phytopathogenic and toxinogenic fungi. The
morphological and chemotaxonomic characteristics of the strain were consistent with those of the genus
Saccharothrix. Analysis of the 16S rRNA gene sequence of strain SA198 showed a similarity level ranging
between 97.2 and 98.8% within Saccharothrix species, S. australiensis being the most closely related. Two
new active products were isolated by reverse HPLC using a C18 column. The ultraviolet–visible (UV–VIS),
infrared (IR), mass, and 1Hand 14C nuclear magnetic resonance (NMR) spectra showed that these products
were new bioactive compounds. The minimum inhibitory concentrations of these antibiotics showed a
strong activity against fungi and moderate activities against Gram-positive and Gram-negative bacteria
Kinetic study of the growth of Saccharothrix algeriensis DSM 44581 in batch fermenter on a semi-synthetic medium in the presence of tiglic acid and methacrylic acid
This work aimed to investigate the effect of some nutriments (tiglic acid and methacrylic acid) on the growth of Saccharothrix algeriensis DSM 44581 on chemically defined medium (semi-synthetic medium) by using controlled batch fermenters. The controlled batch fermentations were conducted in the presence of tiglic and methacrylic acids. The growth rate of S. algeriensis in all fermentations was fast during the first 10 h of fermentation. The control culture showed a partially cell lysis in comparison to cultures with organic acids. This result showing that these organic acids could be used for biomass maintaining. The formation of biomass was influenced by the addition of organic acids. The experiment in the fermentor showed some differences with results obtained in Erlenmeyers
Making wine safer: the case of ochratoxin A
This study aims to assess the risk of ochratoxin A (OTA) in European wine
with the objective of reducing toxin levels through an integrated management
of production and processing. All European countries of the Mediterranean
basin are involved. Preliminary results indicate that OTA producing fungi
are already present on grapes in the vineyard, prior to harvest. Vineyard
location has more influence on OTA levels than grape variety. Weather patterns
also seem to influence OTA levels. Results obtained from applications of various adjuvants aimed at reducing and/or eliminating OTA in wine are
discussed.info:eu-repo/semantics/publishedVersio
Visualization of grapevine root colonization by the Saharan soil isolate Saccharothrix algeriensis NRRL B-24137 using DOPE-FISH microscopy
Background and aim There is currently a gap of
knowledge regarding whether some beneficial bacteria
isolated from desert soils can colonize epi- and
endophytically plants of temperate regions. In this
study, the early steps of the colonization process of
one of these bacteria, Saccharothrix algeriensis NRRL
B-24137, was studied on grapevine roots to determine
if this beneficial strain can colonize a non-natural host
plant. An improved method of fluorescence in situ
hybridization (FISH), the double labeling of oligonucleotide
probes (DOPE)-FISH technique was used to
visualize the colonization behavior of such bacteria as well as to determine if the method could be used to
track microbes on and inside plants.
Methods A probe specific to Saccharothrix spp. was
firstly designed. Visualization of the colonization behavior
of S. algeriensis NRRL B-24137 on and inside
roots of grapevine plants was then carried out with
DOPE-FISH microscopy.
Results The results showed that 10 days after inoculation,
the strain could colonize the root hair zone, root
elongation zone, as well as root emergence sites by
establishing different forms of bacterial structures as
revealed by the DOPE-FISH technique. Further observations
showed that the strain could be also endophytic
inside the endorhiza of grapevine plants.
Conclusions Taking into account the natural niches of
this beneficial strain, this study exemplifies that, in
spite of its isolation from desert soil, the strain can
establish populations as well as subpopulations on and
inside grapevine plants and that the DOPE-FISH tool
can allow to detect it
Saccharothrix sp. PAL54, a new chloramphenicol-producing strain isolated from a Saharan soil
An actinomycete strain designated PAL54, producing an antibacterial substance, was isolated from a Saharan soil in Ghardaïa, Algeria. Morphological and chemical studies indicated that this strain belonged to the genus Saccharothrix. Analysis of the 16S rDNA sequence showed a similarity level ranging between 96.9 and 99.2% within Saccharothrix species, with S. longispora DSM 43749T, the most closely related. DNA–DNA hybridization confirmed that strain PAL54 belonged to Saccharothrix longispora. It showed very strong activity against pathogenic Gram-positive and Gram-negative bacteria responsible for nosocomial infections and resistant to multiple antibiotics. Strain PAL54 secreted the antibiotic optimally during mid-stationary and decline phases of growth. One antibacterial compound was isolated from the culture broth and purified by HPLC. The active compound was elucidated by uv-visible and NMR spectroscopy and by mass spectrometry. The results showed that this compound was a D(-)-threo chloramphenicol. This is the first report of chloramphenicol production by a Saccharothrix species
An overview on molecular markers for detection of ochratoxigenic fungi in coffee neans
Use of beneficial bacteria and their secondary metabolites to control grapevine pathogen diseases
Grapevine is one of the most important economic crops yielding berries, wine products as well as derivates. However, due to the large array of pathogens inducing diseases on this plant, considerable
amounts of pesticides—with possible negative impact on the environment and health—have been used and are currently used in viticulture. To avoid negative impacts of such products and to ensure product quality, a substantial fraction of pesticides needs to be replaced in the near future. One solution can be related to the use of beneficial bacteria inhabiting the rhizo- and/or the endosphere of plants. These biocontrol bacteria and their secondary metabolites can reduce directly or indirectly pathogen diseases by affecting pathogen performance by antibiosis, competition for niches and nutrients, interference with pathogen signaling or by stimulation of host plant defenses. Due to the large demand for biocontrol of grapevine diseases, such biopesticides, their modes of actions and putative consequences of their uses need to be described. Moreover, the current knowledge on new strains from the rhizo- and endosphere and their metabolites that can be used on grapevine plants to counteract pathogen attack needs to be discussed. This is in particular with regard to the control of root rot, grey mould, trunk diseases, powdery and downy mildews, pierce’s disease, grapevine yellows as well as crown gall. Future prospects on specific beneficial microbes and their secondary metabolites that can be used as elicitors of plant defenses and/or as biocontrol agents with potential use in a more sustainable viticulture will be further discussed
The Saharan isolate Saccharothrix algeriensis NRRL B-24137 induces systemic resistance in Arabidopsis thaliana seedlings against Botrytis cinerea
Background and aim Saccharothrix algeriensis NRRL B-24137, isolated from a Saharan soil, has been described as a potential biocontrol agent against Botrytis cinerea and other phytopathogens. However, the plant protection mechanisms involved still need to be described. The aim of this study was to determine this protection phenomenon as well as parts of the mechanisms involved, using Arabidopsis thaliana seedlings and B. cinerea. Methods The bacterial colonization process was evaluated on A. thaliana seedlings using fluorescence in situ hybridization. Protection of A. thaliana seedlings inoculated with NRRL B-24137 against B. cinerea was then evaluated. Parts of the mechanisms involved in the systemic protection against B. cinerea were evaluated using known mutants of genes involved in jasmonate (JA)/ethylene (ET)/salicylic acid (SA) signaling. Other Arabidopsis mutants, AtrhbohD-3, AtrhbohF-3, and ups1-1 were also screened to determine other parts of the mechanisms involved. Results The results showed that the strain NRRL B-24137 colonized, epi- and endophytically, the roots of Arabidopsis seedlings but the strain was not a systemic colonizer during the time of the experiment. The strain NRRL B-24137 also reduced B. cinerea symptoms and the protection was linked to known mechanisms of induced systemic resistance (ISR; JA/ET signaling), as well as to functionality of AtrbohF oxidase and of UPS1. Crosstalk between ET/JA and SA signaling could also be involved. Conclusions The isolate NRRL B-24137, after colonizing the root systems of A. thaliana, induces an ISR against B. cinerea, which is JA/ET dependent, but could also require SA crosstalk and protection could also require NAPDH oxidases and UPS1 functionalities