Possibility of Using the Recycled Fungal Media View PDF

In the field of microbiology (bacteria, fungi), it has been widely reported that solid media consisting of a mixture of agar, salts, vitamins, colorings and some texture enhancers [1,2], are used to identify and isolate the microorganisms and these media, on the other hand, produce biological waste. The biological wastes management becomes more important, especially with the growing factories and population; and in the developing countries the media could be expensive [3,4]. Limited studies have referred to the reuse of media [2,5]; re-dissolve the media by heating in autoclaves after take out the bacterial colonies from the media, after transforming the small pieces of used media to new liquid to be poured directly into the Petri dishes [2], whom dissolved only the bacterial medium, without converting it to a dry storable material, and therefore it could be used immediately after recycling for only one time. While other researchers were able to recycle the used bacterial media and plant tissue culture into new agar in a form of a dry substance after treatment with some chemicals [5], but without providing data on recycling fungal media or testing the ability of fungi to grow on the recycled media. Recently, Abboudi M (2021) [4], also addressed the possibility of recycling bacterial culture media, but not the fungal media.

Some reports have attempted to replace the basic traditional culture media (NA: Nutrient agar, PDA: Potato Dextrose Agar, SDA: Sabourod Dextrose Agar) with cheaper natural materials such as grains, vegetables and fruit peels for the development of fungi [3,6, and 7], to be used for economical and ecological reasons. Algae culture medium can be recycled up to four times only by centrifugation after growth and with additives (50% of nutrients of urea media) during anaerobic fermentation processes [8-11]. There is no indication about the recycling of fungal culture media or the extraction of agar from these media. The media can have different impacts on the quality of fungal during the growth [12]. 

Some studies have addressed the effect of environment on the fungal growth through the measurement of mycelial mat and the change in the color of fungi. The effect of growth temperature, medium composition and pH of media could affect the products of fungal growth [13], and the modification of the normally media -such as Sabouraud agar- could be technically useful in simultaneous fungal enumeration and determination of the presence of some product without prior isolation [14]. Benefiting from different culture media is of scientific and technical work that deserves attention for two reasons. Firstly, its importance in the recycling of biological waste and thus recycling the plastic Petri dishes used in food, industry and health laboratories as well. Secondly, obtaining of biological materials recycled for several times in the form of a powder that can be stored for long periods, and then used again in all biological and bacteriological experiments, and additional fund is needed to purchase new media, which is very expensive in developing countries. As far as we know from literature, there is no technique to safely dispose of used Petri dishes that contain fungal colonies, except using high humid heat (autoclave), which forms large quantities of biological waste. The aim of the present work was to look for environmental and economical solutions for the big quantities of biological wastes caused by fungal culture in food factories and scientific laboratories.