Fungal endophytes from leaves of Mandevilla catimbauensis (Apocynaceae): diversity and potential for L-asparaginase production.

In this study, we examined endophytic fungi in leaves of Mandevilla catimbauensis, an endemic plant species found in the Brazilian dry forest (Caatinga), and endophytic fungi's potential to produce L-asparaginase (L-ASNase). In total, 66 endophytes were isolated, and the leaf-fragment colonisation rate was 11.78%. Based on morphology, internal transcribed spacer (ITS), and partial large subunit (LSU) of ribosomal DNA sequencing, the endophytic fungi isolated belonged to six Ascomycota orders (Botryosphaeriales, Capnodiales, Diaporthales, Eurotiales, Marthamycetales, and Pleosporales). Phyllosticta species were the most frequent endophytes isolated (23 isolates [45.1%] from two species). The Shannon-Wiener and Fisher alpha index average values were 0.56 and 3.26, respectively. Twenty endophytes were randomly selected for the L-ASNase production test, of which fourteen isolates showed potential to produce the enzyme (0.48-2.22 U g-1), especially Phyllosticta catimbauensis URM 7672 (2.22 U g-1) and Cladosporium sp. G45 (2.11 U g-1). Phyllosticta catimbauensis URM 7672 was selected for the partial optimisation of L-ASNase production because of its ability to generate considerable amounts of enzyme. We obtained the highest L-ASNase activity (3.47 U g-1), representing an increase of 36.02% in enzymatic production, under the following experimental conditions: a pH of 4.2, 1.0% inoculum concentration, and 2.5% L-asparagine concentration. Our study showed that M. catimbauensis harbours an important diversity of endophytic fungi with biotechnological potential for L-ASNase production.

Penicillium and Talaromyces endophytes from Tillandsia catimbauensis, a bromeliad endemic in the Brazilian tropical dry forest, and their potential for L-asparaginase production.

This study was conducted to report the richness of endophytic Penicillium and Talaromyces species isolated from Tillandsia catimbauensis, a bromeliad endemic in the Brazilian tropical dry forest (Caatinga), to verify their ability to produce the enzyme L-asparaginase and to partially optimise the production of biomass and L-asparaginase of the best enzyme producer. A total of 184 endophytes were isolated, of which 52 (29%) were identified through morphological and phylogenetic analysis using ß-tubulin sequences into nine putative species, four in Penicillium and five in Talaromyces. Talaromyces diversus and T. cf. cecidicola were the most frequent taxa. Among the 20 endophytic isolates selected for L-asparaginase production, 10 had the potential to produce the enzyme (0.50-2.30 U/g), especially T. cf. cecidicola URM 7826 (2.30 U/g) and Penicillium sp. 4 URM 7827 (1.28 U/g). As T. cf. cecidicola URM 7826 exhibited significant ability to produce the enzyme, it was selected for the partial optimisation of biomass and L-asparaginase production. Results of the 23 factorial experimental design showed that the highest dry biomass (0.66 g) was obtained under pH 6.0, inoculum concentration of 1 × 108 and 1% L-proline. However, the inoculum concentration was found to be statistically significant, the pH was marginally significant and the concentration of L-proline was not statistically significant. L-Asparaginase production varied between 0.58 and 1.02 U/g and did not reach the optimal point for enzyme production. This study demonstrates that T. catimbauensis is colonised by different Penicillium and Talaromyces species, which are indicated for enzyme production studies.