Antifungal Activity of Cell-Free Filtrate of Probiotic Bacteria Lactobacillus rhamnosus ATCC-7469 against Fungal Strains Isolated from a Historical Manuscript

Mahmoud Abdel-Nasser; Gomaa Abdel-Maksoud; Ahmed M Eid; Saad El-Din Hassan; Aya Abdel-Nasser; Maha Alharbi; Amr Elkelish; Amr Fouda

doi:10.3390/microorganisms11051104

Antifungal Activity of Cell-Free Filtrate of Probiotic Bacteria Lactobacillus rhamnosus ATCC-7469 against Fungal Strains Isolated from a Historical Manuscript

Microorganisms. 2023 Apr 23;11(5):1104. doi: 10.3390/microorganisms11051104.

Authors

Mahmoud Abdel-Nasser¹, Gomaa Abdel-Maksoud², Ahmed M Eid³, Saad El-Din Hassan³, Aya Abdel-Nasser⁴, Maha Alharbi⁵, Amr Elkelish^{6

7}, Amr Fouda³

Affiliations

¹ Department of Manuscripts Conservation, Al-Azhar Al-Sharif Library, Cairo 11511, Egypt.
² Conservation Department, Faculty of Archaeology, Cairo University, Giza 12613, Egypt.
³ Department of Botany and Microbiology, Faculty of Science, Al-Azhar University, Cairo 11884, Egypt.
⁴ Food Toxicology and Contaminants Department, National Research Centre, Giza 12622, Egypt.
⁵ Department of Biology, College of Science, Princess Nourah Bint Abdulrahman University, P.O. Box 84428, Riyadh 11671, Saudi Arabia.
⁶ Biology Department, College of Science, Imam Mohammad Ibn Saud Islamic University (IMSIU), P.O. Box 90950, Riyadh 11623, Saudi Arabia.
⁷ Botany and Microbiology Department, Faculty of Science, Suez Canal University, Ismailia 41522, Egypt.

Abstract

Herein, twelve fungal strains were isolated from a deteriorated historical manuscript dated back to the 18th century. The obtained fungal strains were identified, using the traditional method and ITS sequence analysis, as Cladosporium herbarum (two strains), Aspergillus fumigatus (five strains), A. ustus (one strain), A. flavus (two strains), A. niger (one strain), and Penicillium chrysogenum (one strain). The ability of these fungal strains to degrade the main components of the paper was investigated by their activity to secrete extracellular enzymes including cellulase, amylase, gelatinase, and pectinase. The cell-free filtrate (CFF) ability of the probiotic bacterial strain Lactobacillus rhamnosus ATCC-7469 to inhibit fungal growth was investigated. The metabolic profile of CFF was detected by GC-MS analysis, which confirmed the low and high molecular weight of various active chemical compounds. The safe dose to be used for the biocontrol of fungal growth was selected by investigating the biocompatibility of CFF and two normal cell lines, Wi38 (normal lung tissue) and HFB4 (normal human skin melanocyte). Data showed that the CFF has a cytotoxic effect against the two normal cell lines at high concentrations, with IC₅₀ values of 525.2 ± 9.8 and 329.1 ± 4.2 µg mL^-1 for Wi38 and HFB4, respectively. The antifungal activity showed that the CFF has promising activity against all fungal strains in a concentration-dependent manner. The highest antifungal activity (100%) was recorded for a concentration of 300 µg mL^-1 with a zone of inhibition (ZOI) in the ranges of 21.3 ± 0.6 to 17.7 ± 0.5 mm. At a concentration of 100 µg mL^-1, the activity of CFF remained effective against all fungal strains (100%), but its effectiveness decreased to only inhibit the growth of eight strains (66%) out of the total at 50 µg mL^-1. In general, probiotic bacterial strains containing CFF are safe and can be considered as a potential option for inhibiting the growth of various fungal strains. It is recommended that they be used in the preservation of degraded historical papers.

Keywords: Lactobacillus spp.; analytical techniques; biocontrol; fungi; historical manuscript; probiotic bacteria.

Grants and funding

This research received no external funding.