Biology subjects

Sondergaard, T. E.

Publications and source records attributed to Sondergaard, T. E..

4 recordsLinked to original sources

bioRxiv2026

Using CarboTrace 480 to detect protoplastation in pigment deficient mutant of Chlorella sorokiniana

The increasing world population necessitates new sustainable nutrient sources, making microalgae like Chlorella sorokiniana interesting due to its rich nutrient profile and sustainable cultivation methods. With genetic optimization tools like CRISPR/Cas9, microalgae as a nutrient source can be improved even further. However, degradation of the rigid cell wall of microalgae, and thereby developing protoplasts, is often necessary prior to transformation, but monitoring protoplast development in spherical, single-celled organisms like C. sorokiniana is challenging using bright-field microscopy. Carbotrace 480 and 630 were tested as fluorescent markers of the cell wall of a C. sorokiniana mutant for protoplast detection, and Carbotrace 480 was successfully used to distinguish protoplast from normal cells in a cell suspension. The enzymes Driselase, Glucanex, Snailase, and Saczyme were tested in different combinations to degrade the cell wall of the mutant, with Snailase as the most effective yielding ~60 % protoplasts. This study provides a quick and easy tool for monitoring protoplast development in the microalgae C. sorokiniana, the first step to improve C. sorokiniana as a sustainable nutrient source using genetic optimization tools like CRISPR/Cas9.

bioengineering↗

bioRxiv2026

Non-ribosomal Peptides as Structural Determinants of Fungal Hydrophobicity

Fungal surfaces must remain hydrophobic to enable growth, dispersal, and survival under fluctuating environmental conditions, yet the molecular basis of this property remains incompletely understood. Here, we identify fungisporins, fusahexins, and related cyclic non-ribosomal peptides (NRPs) as members of a conserved functional class of fungal metabolites, termed WAter Repellent Peptides (WARPs), that are required for fungal surface hydrophobicity. Across filamentous fungi, WARPs vary substantially in sequence and length but share conserved structural features, including cyclization, hydrophobic amino acid composition, and alternating D- and L-configurations, consistent with a flexible amphiphilic scaffold. Loss of WARP-producing non-ribosomal peptide synthetases results in rapid collapse of aerial hyphae upon water exposure, demonstrating that these peptides are required for maintenance of hydrophobic aerial structures. Using phage-display-derived antibodies, we localize WARPs to the hyphal surface, supporting their role as surface-associated structural components. Together, these findings identify a conserved NRPS-encoded peptide system that contributes to fungal hydrophobicity and establish WARPs as a broadly distributed class of surface-associated metabolites with structural function in filamentous fungi.

microbiology↗

bioRxiv2026

An activity-resistance tradeoff constrains enzyme evolution

The presence of self-resistance genes in antibiotic-producing organisms poses a paradox: how can resistance evolve before the antibiotic exists, and how can an antibiotic producer arise without first evolving resistance? Here we examine the evolutionary origins of self-resistance to mycophenolic acid (MPA), an inhibitor of inosine monophosphate dehydrogenase (IMPDH). The MPA biosynthetic gene cluster (BGC) includes a resistant IMPDH-B. Homologs of IMPDH-B occur not only in MPA producers but also in many non-producing fungi, where remnants of the MPA BGC remain detectable. The phylogeny of IMPDH-B is incongruent with the fungal species tree, consistent with multiple horizontal gene transfer events between Aspergillus and Sordariomycetes. We characterized eleven extant IMPDH-Bs, five from MPA producers and six from nonproducers, along with seven resurrected ancestral enzymes (Anc1-Anc7). MPA resistance appeared between Anc2 and Anc3 and coincided with a loss of catalytic efficiency. Across both ancestral and extant enzymes, MPA resistance correlated strongly with reduced activity, revealing a robust activity-resistance trade-off that has persisted for millions of years. Unexpectedly, both the IMPDH-Bs and ancestral enzymes Anc3-Anc7 were also resistant to ribavirin-5'-monophosphate (RVP), an IMP-competitive inhibitor. Because MPA and RVP bind to similar enzyme conformations, the activity-resistance trade-off likely reflects a design constraint imposed by the need to maintain resistance to multiple inhibitors. Intriguingly, although Anc1 and Anc2 are equally sensitive to MPA, Anc2 shows reduced susceptibility to RVP. This pattern suggests that pre-existing resistance to another IMPDH inhibitor may have created a permissive background for the later evolution of MPA biosynthesis. SignificanceAntibiotic producers must be resistant to the toxins that they produce, but how such self-resistance develops is a mystery. The mycophenolic acid (MPA) biosynthetic gene cluster (BGC) encodes a resistant variant of the MPA target IMPDH (IMPDH-B). Many fungi retain IMPDH-B although they have lost the ability to produce MPA. The IMPDH-B and species phylogenies are incongruent, suggesting evolution of the BGC was complicated. MPA resistance correlates with low catalytic efficiency in modern and ancestral IMPDHs, revealing a robust design constraint tradeoff. Surprisingly, IMPDH-Bs are also resistant to an IMP-competitive inhibitor (RVP). RVP resistance appears to have emerged before MPA resistance. Perhaps resistance to RVP created a background that permitted the genesis of a new toxin.

evolutionary biology↗

bioRxiv2023

Cladosporium species detoxify multiple water micropollutants of emerging concern using diverse strategies

The accumulation of micropollutants of emerging concern in aqueous systems raises safety concerns regarding biological systems and human health. Mycoremediation is a promising and green strategy to mitigate the micropollutant challenge. Hitherto, focus has mainly been on white-rot Basidiomycota and micropollutant transformation by ascomycetes remains underexplored. Here, we assayed 53 Ascomycota isolates from 10 genera for the removal of 22 micropollutants. Notably, 9 out of 22 micropollutants were removed from fungal culture supernatant at efficacies >45%. Temporal analysis of the nine top- performing strains, highlighted remarkable potency of Cladosporium isolates in removal of multiple micropollutants. Importantly, Cladosporium considerably reduced the toxicity of a micropollutant cocktail based on growth assays. Metabolomics analyses identified oxidation for 5-methyl-1H-benzotriazole and citalopram, whereas methylation and carboxylation were observed for 5-chlorobenzotriazole. No transformation products were detected for ciprofloxacin, sulfamethoxazole, and sertraline, hinting their extensive degradation. These findings suggest micropollutant transformation via diverse catalytic routes by Cladosporium. Genome sequencing and proteomic analyses of the top-performing isolates were consistent with the observed transformations and tentatively identified the molecular apparatus, conferring micropollutant transformation. This unprecedented study brings novel insight into the micropollutant transformation and detoxification capabilities of the prevalent Cladosporium species, thereby revealing a considerable and hitherto underappreciated potential of this genus and potentially other ascomycetes in micropollutant transformation. ImportanceAt present, conventional wastewater treatment plants (WWTPs) are not designed for removing micropollutants, which are released into aqueous systems. This raises concerns due to the poor insight into micropollutant long-term interplay with biological systems. Innovating biotechnological solutions to tackle micropollutant require addressing the paucity of knowledge on microbial groups and molecular pathways, which mediate micropollutant transformation. Our study highlights the considerable potential of the Cladosporium genus that remains underexplored in the arena of micropollutant transformation. We report the first genomes sequences for three Cladosporium species: C. allicinum, C. inversicolor, and C. fusiforme, which sets the stage for further analyses of micropollutant transformation, but also offers an important resource on this ecologically significant, albeit under-studied genus and related Ascomycota.

microbiology↗