A unique fungal strain collection from Vietnam characterized for high performance degraders of bioecological important biopolymers and lipids

Abstract

Fungal strains are abundantly used throughout all areas of biotechnology and many of them are adapted to degrade complex biopolymers like chitin or lignocellulose. We therefore assembled a collection of 295 fungi from nine different habitats in Vietnam, known for its rich biodiversity, and investigated their cellulase, chitinase, xylanase and lipase activity. The collection consists of 70 isolates from wood, 55 from soil, 44 from rice straw, 3 found on fruits, 24 from oil environments (butchery), 12 from hot springs, 47 from insects as well as 27 from shrimp shells and 13 strains from crab shells. These strains were cultivated and selected by growth differences to enrich phenotypes, resulting in 211 visually different fungi. DNA isolation of 183 isolates and phylogenetic analysis was performed and 164 species were identified. All were subjected to enzyme activity assays, yielding high activities for every investigated enzyme set. In general, enzyme activity corresponded with the environment of which the strain was isolated from. Therefore, highest cellulase activity strains were isolated from wood substrates, rice straw and soil and similar substrate effects were observed for chitinase and lipase activity. Xylanase activity was similarly distributed as cellulase activity, but substantial activity was also found from fungi isolated from insects and shrimp shells. Seven strains displayed significant activities against three of the four tested substrates, while three degraded all four investigated carbon sources. The collection will be an important source for further studies. Therefore representative strains were made available to the scientific community and deposited in the public collection of the Leibniz-Institute DSMZ–German Collection of Microorganisms and Cell Cultures, Braunschweig.

Aspergillus sydowii: Genome Analysis and Characterization of Two Heterologous Expressed, Non-redundant Xylanases

“…The A. sydowii strain was isolated from shrimp shells in Vietnam according to Brandt et al (2018). Fungal mycelium was cultured in liquid potato-dextrose-broth (PDB) at 28°C with 150 rpm and used to isolate DNA.…”

“…Based on aligned results of filtered reads and reference sequence, the single nucleotide polymorphisms (SNPs) and an insertions or deletions of bases (InDels) are annotated. From the unique fungal strain collection from Vietnam (Brandt et al, 2018), 10 strains from Aspergillus as well as ITS sequences from 33 Aspergillus spp., two Penicillium spp., two Fusarium spp., and one Eurotium rubum retrieved from MycoBank (Robert et al, 2013), have been used. The phylogenetic tree ( Figure 1B) was inferred under the maximum likelihood (ML; Guindon et al, 2010), from sequences of the internal transcribed spacers 1 and 2, aligned with ClustalW (Thompson et al, 1994) with gap open cost of 15 and gap extend cost of 6.66 with free end gaps.…”

“…This strain was part of a collection previously isolated from nine different substrates and environments, collected from the biodiverse country Vietnam. They were analyzed for their potential do degrade lipids, chitin, cellulose, and xylan (Brandt et al, 2018). Twelve highly active xylan degraders were identified, while two of them were Aspergillus strains with high activities in all four investigated assays.…”

“…PDA, potato-dextrose-agar; YPD, yeast extract peptone dextrose; CM, complete media; and ME, malt extract agar. (B) Phylogenetic tree from Aspergillus clades of ITS sequences from the unique fungal strain collection from Vietnam (Brandt et al, 2018) with two strains of Fusarium and one for Magnaporthe grisea, as well as one for Eurotium rubum. Phylogenetic tree highlighting the position of A. sydowii isolate and closely related type strains.…”

Heliocephala variabilis and Pseudopenidiella vietnamensis: Two New Hyphomycetous Species in the Microthyriaceae (Dothideomycetes) from Vietnam

“…Vietnam is one of the twenty most bio-diverse countries in the world [1][2][3]. Its very diverse ecological niches, climatic conditions, and high level of plant endemism would suggest that the country also has great fungal diversity, although this has been not extensively studied so far [4][5][6]. During a survey of asexual microfungi from plant debris carried out in the Northeast of Vietnam, two interesting specimens, belonging to the genera Heliocephala and Pseudopenidiella (Microthyriaceae, Microthyriales, Dothideomycetes) [7] were isolated and deposited in the culture collection at the Medicine Faculty of the Universitat Rovira i Virgili (Reus, Spain) for subsequent studies.…”