Prevalence of lipase producer Aspergillus niger in nuts and anti-biofilm efficacy of its crude lipase against some human pathogenic bacteria

Abstract

Nuts are the natural source of healthy lipids, proteins, and omega-3. They are susceptible to fungal and mycotoxins contamination because of their high nutritional value. Twenty-five species comprising 12 genera were isolated from 80 samples of dried fruits and nuts using the dilution plate method. Peanut recorded the highest level of contamination followed by coconut; almond and raisin were the lowest. Aspergillus was the most prevalent genus and A.niger, was the most dominant species. The morphological identification of the selected A.niger isolates as they were detected in high frequency of occurrence was confirmed by using 18SrRNA sequence. Ochratoxin biosynthesis gene Aopks was detected in the tested isolates. Lipase production by the selected A.niger isolates was determined with enzyme activity index (EAI) ranging from 2.02 to 3.28. A.niger-26 was the highest lipase producer with enzyme activity of 0.6 ± 0.1 U/ml by the trimetric method. Lip2 gene was also detected in the tested isolates. Finally, the antibacterial and antibiofilm efficiency of crude lipase against some human pathogens was monitored. Results exhibited great antibacterial efficacy with minimum bactericidal concentration (MBC) of 20 to 40 µl/100 µl against Escherichiacoli, Pseudomonasaeruginosa, Proteusmirabilis, and Methicillin-resistant Staphylococcusaureus (MRSA). Interestingly, significant anti-biofilm efficacy with inhibition percentages of 95.3, 74.9, 77.1 and 93.6% was observed against the tested pathogens, respectively.

Fungi Occurrence in Ready-to-Eat Hazelnuts (Corylus avellana) From Different Boreal Hemisphere Areas

“…Aspergillus is recognized as the most common genera causing nuts spoilage, and their ingestion may cause mycoses, especially in immunocompromised patients ( Yassein et al, 2021 ). In fact, despite the industrial importance of both Aspergillus nige r and Aspergillus ochraceus , they are recognized as producers of mycotoxins, namely ochratoxin A (OTA) and fumonisin B2 (FB2) ( Frisvad et al, 2004 , 2007 ; Dasan et al, 2016 ).…”

Towards sustainable Cleaning‐in‐Place (CIP) in dairy processing: Exploring enzyme‐based approaches to cleaning in the Cheese industry

“…PUMB02 and a marine sponge-derived lipase (Lpc53E1) showed 90%-95% disruption of biofilms of various pathogens such as B. cereus, Listeria sp., E. coli, Serratia sp., and Vibrio parahaemolyticus (Kiran et al, 2014). Similarly, Yassein et al (2021) demonstrated that a lipase isolated from Aspergillus niger MW029470 achieved a 77.1%, 74.9%, 93.6%, and 95.3% inhibition of the biofilms against biofilms of Proteus mirabilis, P. aeruginosa, methicillin-resistant S. aureus, and E. coli, respectively.…”

“…Similarly, Yassein et al. (2021) demonstrated that a lipase isolated from Aspergillus niger MW029470 achieved a 77.1%, 74.9%, 93.6%, and 95.3% inhibition of the biofilms against biofilms of Proteus mirabilis , P. aeruginosa , methicillin‐resistant S. aureus , and E. coli , respectively.…”

Isolation and identification of Biofilm-producing E. coli from drinking water.

“…For 30 seconds, slides were stained negatively with 0.2 percent uranyl acetate. GOEL-JEM-1200 EX II electron microscope was used to investigate these slides 22 .…”