Quantification of superficial growth and the pigmentation of filamentous fungi by effect of oscillating magnetic field

This work was to quantify the superficial growth and the pigmentation of filamentous fungi colonies by effect of an extremely low frequency oscillating magnetic field (OMF-ELF) depending on nutritional status of these microorganisms in two culture media. OMF-ELF of 2 mT by 60 Hz/200 V during 2 h (optimization of an experimental design) was applied at two filamentous fungi strains isolated from indoor environments: Aspergillus niger (hyaline mycelium seen under the optic microscope) and Cladosporium cladosporioides (pigmented mycelium), this latter strain was used as a negative control. The strains were inoculated in Petri dishes with Malt Extract Agar (MEA) and Czapek Dox Agar (CDA), incubated at 30ºC and photographs were taken every 4 hours for 10 days. The area (superficial growth) and color intensity (pigmentation) of these colonies were evaluated by digital images processing (DIP) using MatLab®. The stimulating effect of OMF-ELF on the cellular metabolism of both fungal strains was demonstrated, with an increase of the superficial growth and a greater variation in pigmentation (indicative of sporulation by conidiogenesis) in CDA until reaching values of spores similar to when there are enough nutrients (MEA). The predictive mathematical model obtained by optimization of the experimental design to predict the growth of Aspergillus niger colony was validated with the algorithm implemented for the DIP. It was concluded that the OMF-ELF stimulated the metabolism of the studied fungal strains independently of the nutrients in the culture media and that the DIP is a precise technique to quantify the macroscopic phenomena that occur due to magnetobiological effects at the cellular level

Study of environmental conditions in the repositories of the National Archive of the Republic of Cuba

The aim was to study the behavior of the temperature (T), relative humidity (RH) and illuminance (I) in the repositories of the National Archive of the Republic of Cuba. The values of T and RH were measured twice daily for four consecutive years. I was measured in sunny and cloudy days. The result sallow us to affirm that the environmental conditions (T, RH) of these repositories are favorable for the conservation of paper documents. In cloudy days, I of the repositories located in lower-ground floor does not exceed the allowed 50 lux; but in sunny days, due to the incidence of sunlight, in all repositories I exceeds 50 lux. Artificial light caused an increase in I in all repositories, but this is not significant because the light bulbs are kept turned off most of the time