Related Experiment Video

Updated: Jan 20, 2026

MALDI-ToF MS Method for the Characterization of Synthetic Polymers with Varying Dispersity and End Groups

MALDI-ToF MS Method for the Characterization of Synthetic Polymers with Varying Dispersity and End Groups

Published on: October 3, 2025

Polyphasic, Including MALDI-TOF MS, Evaluation of Freeze-Drying Long-Term Preservation on Aspergillus (Section Nigri)

Rodrigo Rodriguez¹, Carla Santos¹, Marta F Simões²

¹CEB-Centre of Biological Engineering, Micoteca da Universidade do Minho, University of Minho, 4710-057 Braga, Portugal.

|August 28, 2019

Abstract:

This study aims to evaluate the effect of freeze-drying and long-term storage on the biotechnological potential of Aspergillus section Nigri strains. Twelve selected strains were freeze-dried and aged by accelerated storage, at 37 °C in the dark, for 2 and 4 weeks. To assess possible changes as a consequence of the ageing in the freeze-drying ampoules, morphological characteristics, mycotoxins and enzymes production, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALTI-TOF MS) spectra, and M13 phage probe fingerprinting were used as part of a polyphasic approach. Phenotypical changes were observed; nevertheless, they did not substantially affect the potential biotechnological use of these strains. The activity of hydrolytic enzymes (protease, carboxymethylcellulase, xylanase, pectinase and mannanase) was maintained or increased after freeze-drying. MALDI-TOF MS data originated spectra that grouped, for the majority of samples, according to strain independently of preservation time point. M13 profiles revealed the presence of some genetic polymorphisms after preservation. However, the three studied times still clustered for more than 50% of strains. Our results show that the studied strains maintain their biotechnological potential after preservation, with minimal phenotypic alterations. These findings provide evidence that freeze-drying preservation is a suitable option to preserve biotechnologically relevant aspergilli strains from section Nigri, and one should consider that the observed effects might be species/strain-dependent.

Insights

Freeze-drying preservation maintains the biotechnological potential of Aspergillus section Nigri strains, with minimal phenotypic changes observed after long-term storage. Enzyme activity and genetic profiles remained largely stable, confirming its suitability for these fungi.

Area of Science:

Microbiology
Biotechnology
Industrial Mycology

Background:

Aspergillus section Nigri strains are valuable for biotechnology.
Effective preservation methods are crucial for maintaining their long-term viability and function.
Freeze-drying is a common preservation technique, but its impact on these specific strains requires evaluation.

Purpose of the Study:

To assess the effects of freeze-drying and accelerated long-term storage on the biotechnological potential of Aspergillus section Nigri strains.
To investigate alterations in morphological characteristics, mycotoxin and enzyme production, and genetic profiles post-preservation.
To determine the suitability of freeze-drying for preserving these industrially relevant fungal strains.

Main Methods:

Twelve Aspergillus section Nigri strains were freeze-dried and stored at 37 °C for 2 and 4 weeks.
A polyphasic approach was employed, including morphological analysis, mycotoxin and enzyme assays, MALDI-TOF MS, and M13 phage probe fingerprinting.
Comparative analysis was performed between preserved and unpreserved samples.

Main Results:

Minimal phenotypic changes were observed, with hydrolytic enzyme activity (protease, cellulase, xylanase, pectinase, mannanase) maintained or increased.
MALDI-TOF MS spectra generally grouped strains independently of storage duration.
M13 profiles indicated minor genetic polymorphisms, but over 50% of strains clustered across preservation time points.

Conclusions:

Freeze-drying is a suitable method for preserving the biotechnological potential of Aspergillus section Nigri strains.
Preservation resulted in minimal phenotypic alterations and largely maintained strain identity and enzyme activity.
Observed effects may vary depending on the specific species and strain of Aspergillus.

Read full analysis

Keywords:

DNA fingerprinting accelerated ageing biotechnological potential freeze-drying mass spectrometry

More Related Videos

Identification of Rare Bacterial Pathogens by 16S rRNA Gene Sequencing and MALDI-TOF MS

Identification of Rare Bacterial Pathogens by 16S rRNA Gene Sequencing and MALDI-TOF MS

Published on: July 11, 2016

Using the Open-Source MALDI TOF-MS IDBac Pipeline for Analysis of Microbial Protein and Specialized Metabolite Data

Using the Open-Source MALDI TOF-MS IDBac Pipeline for Analysis of Microbial Protein and Specialized Metabolite Data

Published on: May 15, 2019

Related Concept Videos

MALDI-TOF Mass Spectrometry

MALDI-TOF Mass Spectrometry

Mass spectrometry is a powerful characterization technique that can identify and separate a wide variety of compounds ranging from chemical to biological entities, based on their mass-to-charge ratio (m/z). The instruments that allow this detection, known as mass spectrometers, have three components: an ion source, a mass analyzer, and a detector. These spectrometers differ based on the nature of their ion source and analyzers.Matrix-assisted laser desorption ionization (MALDI) is a commonly...

Freezing Point Depression and Boiling Point Elevation

Freezing Point Depression and Boiling Point Elevation

Boiling Point Elevation
The boiling point of a liquid is the temperature at which its vapor pressure is equal to ambient atmospheric pressure. Since the vapor pressure of a solution is lowered due to the presence of nonvolatile solutes, it stands to reason that the solution’s boiling point will subsequently be increased. Vapor pressure increases with temperature, and so a solution will require a higher temperature than will pure solvent to achieve any given vapor pressure, including one...

Phase Transitions: Melting and Freezing

Phase Transitions: Melting and Freezing

Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...

Long-term Depression

Long-term Depression

Long-term depression, or LTD, is one of the ways by which synaptic plasticity—changes in the strength of chemical synapses—can occur in the brain. LTD is the process of synaptic weakening that occurs over time between pre and postsynaptic neuronal connections. The synaptic weakening of LTD works in opposition to synaptic strengthening by long-term potentiation (LTP) and together are the main mechanisms that underlie learning and memory.

Dry Friction

Dry Friction

Dry friction occurs between two solid surfaces in contact as they attempt to move relative to one another. In daily life, dry friction is encountered in various forms, such as when walking on the ground, sliding an object across a table, or rubbing hands together. Despite its ubiquity, the underlying mechanisms behind dry friction are not readily visible.
To illustrate this concept, imagine a wooden crate resting on a rough, non-uniform horizontal surface. When an external force is applied to...

Drying Shrinkage

Drying Shrinkage

When hardened concrete is exposed to air with a relative humidity of less than 100 percent, it begins to lose the free water within its capillaries. As this water evaporates, the water initially adsorbed onto the calcium silicate hydrates migrates towards these now empty spaces and eventually evaporates as well. Over time, as more water leaves, the volume of the concrete decreases, a phenomenon known as drying shrinkage.
A portion of this drying shrinkage can be reversed; if the concrete is...

Articles linked to this work by shared authors, journal, and citation graph.

Trace metal distribution in seawater, brown algae, and seagrasses from Guanahacabibes National Park, Cuba.

Environmental monitoring and assessment·2026

Molecular characterization and antifungal susceptibility of Aspergillus spp. isolated from critically ill COVID-19 patients: implications for suspected COVID-19-associated pulmonary aspergillosis (CAPA) in a Brazilian tertiary referral hospital.

Medical mycology·2026

Chitosan-based nanocarriers for controlled nitric oxide delivery improve physiological performance and stress tolerance in lettuce under saline irrigation.

International journal of biological macromolecules·2026

Forest conversion is more strongly associated with soil microbial functioning than chronic trace element exposure in an industrialized coastal mediterranean ecosystem.

Environmental pollution (Barking, Essex : 1987)·2026

Underutilised Crops for a Sustainable Future: Promoting Resilience and Nutrition in Global Food Systems.

Physiologia plantarum·2026

Foliar Application of Chitosan Nanoparticles Mitigates Early Physiological and Antioxidant Responses of Solanum lycopersicum L. Seedlings Under Mild-to-Moderate Water Deficit.

Polymers·2026

See all related articles