The mycological profile of the retail wheat flour selling in different markets at Jeddah (Kingdom of Saudi Arabia) was studied. The most common genera were Aspergillus (isolated from 70% of the tested samples), Penicillium (30%), Eurotium (14%), and in a lesser extent Fusarium (20%) and Alternaria (18%). Twenty-nine strains of Aspergillus flavus were screened for their ability to produce aflatoxins (AFs). Four strains produced only aflatoxin B1 (AFB1), two strains produced AFB1 and aflatoxin B2, and one strain produced AFB1, aflatoxin G1, and aflatoxin G2. Random amplified polymorphic DNA-polymerase chain reaction technique could not differentiate between toxigenic and nontoxigenic strains of A. flavus. AF regulatory gene was detected in three flour samples and in seven A. flavus isolates.
Background:Endophytic fungi, which have been reported in numerous plant species, are important components of the forest community and contribute significantly to the diversity of natural ecosystems.Objectives:The current study aimed to evaluate and characterize, at the molecular level, the diversity and antimicrobial activities of endophytic fungi from medicinal plants in Saudi Arabia.Materials and Methods:Fungi growing on plant segments were isolated and identified based on morphological and molecular characteristics. The isolates were grouped into 35 distinct operational taxonomic units, based on the sequence of the internal transcribed spacer regions in the rRNA gene. The colonization frequency and the dominant fungi percentage of these endophytic fungi were calculated. A dual culture technique was adopted to investigate the antifungal activity of these endophytes.Results:Tamarix nilotica showed the highest endophytic diversity with a relative frequency of 27.27%, followed by Cressa cretica with a relative frequency of 19.27%. The most frequently isolated species was Penicillium chrysogenum with an overall colonization rate of 98.57%. Seven out of 35 endophytic fungi exhibited strong antifungal activity to all plant fungal pathogens tested. P. chrysogenum, Fusarium oxysporum, and F. nygamai exhibited the highest inhibition against the human pathogenic bacteria Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Aspergillus sydowii, P. chrysogenum, and Eupenicillium crustaceum showed strong antimicrobial activity against Enterococcus faecalis.Conclusions:The antimicrobial activity of these endophytic microorganisms could be exploited in biotechnology, medicine, and agriculture.
Fungal endophytes were isolated from the leaves of Calotropis procera (Apocynaceae) collected from Taif region (Saudi Arabia). Thirty-three different taxa were recovered. The overall foliar colonization rate was 35.1%. A total of 161 isolates were obtained and identified into 33 distinct operational taxonomic units based on the sequencing of the internal transcribed spacer regions of the rRNA gene. The most prevalent fungi were Aspergillus flavus, Chaetomium globosum, Cochliobolus lunatus, Fusarium dimerum, F. oxysporum, and Penicillium chrysogenum. A total of 161 isolates were tested for antifungal activities against four plant pathogenic fungi (Alternaria alternata, Fusarium oxysporum, Botrytis cinerea, and Pythium ultimum), of which 33 isolates showed antifungal activity against at least one plant pathogenic fungi. Four isolates of Chaetomium globosum and three isolates of Myrothecium verrucaria showed the strongest antifungal activity. This study reported the occurrence of a much wider spectrum of fungi, when compared with previous work. Also, it confirmed the variation of different isolates from the same species in terms of antifungal activity.
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