LACTIC ACID BACTERIA AS BIO-PRESERVATIVE AGENTS: ANTIFUNGAL ACTIVITY OF Lactiplantibacillus plantarum AND Levilactobacillus brevis AGAINST FUNGI ISOLATED FROM BIOORGANIC FERTILIZER
KHADIJA ATFAOUI
*
Laboratory of Natural Resources and Sustainable Development, Ibn Tofail University, Kenitra, Morocco.
ABDESSAMAD ETTOUIL
Laboratory of Natural Resources and Sustainable Development, Ibn Tofail University, Kenitra, Morocco.
ASMAA OUBIHI
Laboratory of Natural Resources and Sustainable Development, Ibn Tofail University, Kenitra, Morocco.
ISMAIL LOURAGLI
Laboratory of Nutrition Health and Environment, Department of Biology, Ibn Tofail University, Kenitra, Morocco.
SOUAD HAMMOUTOU
Laboratory of Natural Resources and Sustainable Development, Ibn Tofail University, Kenitra, Morocco.
MOHAMMED OUHSSINE
Laboratory of Natural Resources and Sustainable Development, Ibn Tofail University, Kenitra, Morocco.
*Author to whom correspondence should be addressed.
Abstract
In order to obtain a purely bio-organic fertilizer (free of chemicals and composed entirely of natural by-products), we opted for its preservation from any possible alteration by lactic acid bacteria “LAB”.
Three strains of LABs among 18, previously selected from fermented food products, were screened for their antifungal activity after their identification by 16S rDNA sequencing. These strains were identified as Lactiplantibacillus plantarum NRRL B-14768T “L. plantarum” and Levilactobacillus brevis ATCC 14869T “L. brevis”.
Four fungi susceptible to spoilage a fertilizer composed of olive mill wastewater and rice hulls were used in this study: Fusarium culmorum, Aspergilus Niger, Alternaria alternata, Penicillium sp.
Besides usual methods for detection of antifungal activity: the plug agar technique and the disc diffusion, a combination of qualitative and quantitative methods were used to evaluate this activity named as double layer agar well.
Plug agar method proved that L. plantarum and L. brevis have an antifungal activity against all fungi except A. alternata. Therefore, statistical analysis of the data of disc- diffusion method revealed the same results as the double layer agar well technique. L. brevis displayed a hyper antifungal activity against F. culmorum with a maximum diameter of inhibition zone of 32 mm and A. Niger with a diameter of 15 mm. Moreover, L. plantarum was able to inhibit the growth of Penicillium sp by the three different methods, while no inhibition zone was observed for L. brevis against this fungus.
The results indicated that the combination of the two LABs, L. plantarum and L. brevis is the best alternative to ensure the conservation of the bioorganic fertilizer against fungi that could spoil it.
Keywords: Lactic acid bacteria, Lactiplantibacillus plantarum, Levilactobacillus brevis, spoilage fungi, antifungal activity