Evaluation of Antifungal Activities of Actinobacterial Extracts Isolated from Deep-Sea Laminaria ochroleuca against Pathogenic Fungi †
1
Centro de Investigação e Tecnologias Agroambientais e Biológicas (CITAB), Universidade de Trás-os-Montes e Alto Douro, Quinta de Prados, 5000-801 Vila Real, Portugal
2
Interdisciplinary Center of Marine and Environmental Research, University of Porto, 4450-208 Matosinhos, Portugal
3
School of Medicine and Biomedical Sciences, University of Porto, 4050-313 Porto, Portugal
*
Author to whom correspondence should be addressed.
†
Presented at the 2nd International Electronic Conference on Antibiotics—Drugs for Superbugs: Antibiotic Discovery, Modes of Action and Mechanisms of Resistance, 15–30 Jun 2022; Available online: https://eca2022.sciforum.net/ .
Med. Sci. Forum 2022, 12(1), 10; https://doi.org/10.3390/eca2022-12716
Published: 15 June 2022
(This article belongs to the Proceedings of The 2nd International Electronic Conference on Antibiotics—Drugs for Superbugs: Antibiotic Discovery, Modes of Action and Mechanisms of Resistance)
Antifungal Activity from Marine Actinobacteria
Marine actinobacteria produce secondary metabolites with many biological activities of interest, including antifungals. As fungal infections have increased in the last decade, it is important to search for new compounds. The organisms from the Actinobacteria class, commonly known as actinobacteria are known for their ability to synthetize substances with broad biological activities [1].
In this work, we aimed to evaluate the antifungal activities of marine actinobacteria extracts against several pathogenic fungi.
Thirty extracts of actinobacteria isolated from marine macroalgae and deep-sea samples were screened against fungi: yeasts (Candida albicans ATCC 90028, Candida parapsilosis ATCC 22019, Cryptococcus neoformans PYCC 3957T, Cryptococcus laurentii ZY8) and molds (Aspergillus flavus ATCC 204304, Aspergillus fumigatus ATCC 204305, Aspergillus brasiliensis ATCC 16404). We performed the disk diffusion method (DD), following the CLSI guidelines M44-A, M38-A2 and M61 [2,3,4]. For the determination of the minimum inhibitory/fungicide concentration (MIC/MFC) we chose extracts with inhibition zones ≥ 15 mm, the cut-off for amphotericin B. Additionally, the effect of the best extracts on biofilm and germ tube formation were studied (Candida spp.).
In all organisms and for DD, the susceptibilities varied with fungal species (p < 0.0001) and actinobacterial extracts (p < 0.0001). Cr. neoformans, and C. albicans were the most susceptible species. The highest MICs were obtained for Cryptococcus spp., C. parapsilosis and A. flavus (all MIC >250 µg/mL). For A. brasiliensis, two extracts had the lowest MICs (15.62 µg/mL). The results for C. albicans were in the range of 15.62–125 µg/mL, and for C. parapsilosis MIC was >250 µg/mL. Overall, the MFC ranged from 15.62 to >250 µg/mL. In the biofilm assay, the percentage of inhibition varied greatly between extracts (0–96%). Additionally, some extracts significantly delayed the germ tube formation in C. albicans.
The extracts from actinobacteria isolated from Laminaria ochroleuca exhibited high efficacy against fungi, and mostly against yeasts, particularly in C. albicans (33% of extracts), than the ones from the actinobacteria isolated from Chondrus crispus and Codium tomentosum. The dereplication analysis of the extracts explained the antifungal activity of most of them.
Supplementary Materials
The following are available online at https://sciforum.net/manuscripts/12716/slides.pdf, Poster.
Author Contributions
Conceptualization, A.S. and M.F.C.; methodology, R.M., I.R., M.G. and A.S.; validation, A.S. and M.F.C.; formal analysis, R.M. and A.S.; investigation, R.M., I.R. and M.G.; resources, funding acquisition, and supervision A.S. and M.F.C.; writing—original draft preparation, R.M.; writing—review and editing, M.F.C., M.G. and A.S. All authors have read and agreed to the published version of the manuscript.
Funding
This work was supported by the projects “ATLANTIDA—Platform for the monitoring of the North Atlantic ocean and tools for the sustainable exploitation of the marine resources”, RL4- Marine biobanks as tools for marine biotechnology NORTE-01-0145-FEDER-000040, EP1—Investigação, Desenvolvimento Tecnológico e Inovação), funded by Fundo Europeu de Desenvolvimento Regional (FEDER) through NORTE 2020, and ACTINODEEPSEA (POCI-01-0145-FEDER-031045) co-financed by COMPETE 2020, Portugal 2020 and the European Union through the European Regional Development Fund (ERDF) and by FCT, Portugal, through national funds. RM and AS, are grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support by national funds FCT/MCTES to CITAB (UIDB/04033/2020) and MFC to CIIMAR (UIDB/04423/2020 and UIDP/04423/2020).
Institutional Review Board Statement
Not applicable.
Informed Consent Statement
Not applicable.
Data Availability Statement
Not applicable.
Conflicts of Interest
The authors declare no conflict of interest.
References
- Girão, M.; Ribeiro, I.; Ribeiro, T.; Azevedo, I.C.; Pereira, F.; Urbatzka, R.; Leão, P.N.; Carvalho, M.F. Actinobacteria Isolated from Laminaria ochroleuca: A source of new bioactive compounds. Front. Microbiol. 2019, 10, 683. [Google Scholar] [CrossRef] [PubMed]
- CLSI. CLSI Guideline M44, 3rd ed.; Clinical and Laboratory Standards Institute: Wayne, PA, USA, 2018. [Google Scholar]
- CLSI. Approved Standard—Second Edition. CLSI Document M38-A2; Clinical and Laboratory Standards Institute: Wayne, PA, USA, 2008. [Google Scholar]
- CLSI. CLSI Supplement M61, 1st ed.; Clinical and Laboratory Standards Institute: Wayne, PA, USA, 2017. [Google Scholar]
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MDPI and ACS Style
Maioto, R.; Ribeiro, I.; Girão, M.; Carvalho, M.F.; Sampaio, A. Evaluation of Antifungal Activities of Actinobacterial Extracts Isolated from Deep-Sea Laminaria ochroleuca against Pathogenic Fungi. Med. Sci. Forum 2022, 12, 10. https://doi.org/10.3390/eca2022-12716
AMA Style
Maioto R, Ribeiro I, Girão M, Carvalho MF, Sampaio A. Evaluation of Antifungal Activities of Actinobacterial Extracts Isolated from Deep-Sea Laminaria ochroleuca against Pathogenic Fungi. Medical Sciences Forum. 2022; 12(1):10. https://doi.org/10.3390/eca2022-12716
Chicago/Turabian StyleMaioto, Rita, Inês Ribeiro, Mariana Girão, Maria F. Carvalho, and Ana Sampaio. 2022. "Evaluation of Antifungal Activities of Actinobacterial Extracts Isolated from Deep-Sea Laminaria ochroleuca against Pathogenic Fungi" Medical Sciences Forum 12, no. 1: 10. https://doi.org/10.3390/eca2022-12716
