Biology subjects

Innocenti, P.

Publications and source records attributed to Innocenti, P..

3 recordsLinked to original sources

bioRxiv2025

Lignin degradation and valorization by Pseudomonas putida KT2440: a new role for glutathione peroxidase

Lignin, a complex natural aromatic polymer, poses significant challenges to its efficient degradation, hindering the utilization of biomass for many industrial applications. Bacterial degradation of lignin may offer a promising solution to this challenge. This project aimed at elucidating the function of secreted oxidative enzymes from Pseudomonas putida involved in lignin degradation and utilization. Using CRISPR-Cas9 and CRISPR-Cas3 systems, the putative lignin-degrading versatile peroxidase gene (VP; PP_1686, originally annotated as glutathione peroxidase GPx) and dye-decolorizing peroxidase gene (PP_3248) were individually knocked out from P. putida KT2440. The {Delta}PP_1686 mutant exhibited impaired growth and utilization of lignin-derived compounds. This correlated with reduced expression of p-hydroxybenzoate hydroxylase pobA and of DNA repair modules, alongside compensatory upregulation of energy and redox supply pathways. This work expands our knowledge on bacterial glutathione peroxidase by presenting a role beyond ROS scavenging. This work revealed the importance of P. putida VP/GPx in maintaining redox balance while supporting lignin-derived aromatic metabolism, offering new targets for future investigation into stress-metabolism crosstalk and lignin valorization strategies.

microbiology↗

bioRxiv2025

Antifungal biosynthesis by root-associated Streptomyces and Pseudomonas is elicited upon plant colonization

Plants are colonized by a diverse microbiome, with microorganisms residing inside and outside of plant tissues. Plants can harness the protective traits of their microbial inhabitants to ward off insect pests and fungal pathogens. However, current understanding of the role of commensal interactions on activating the desired microbial genomic traits remains limited. Here we show that biosynthesis of the antifungal 2,5-dihydro-L-phenylalanine (DHP) by the endophytic Streptomyces sp. PG2 is strongly induced upon colonization of Arabidopsis thaliana. DHP production protects the plant from infection by the fungal root pathogen Rhizoctonia solani, both in vitro and in vivo.. We identified the DHP biosynthetic gene cluster (BGC) and showed that heterologous expression of the BGC in the DHP non-producer Streptomyces coelicolor also conferred plant-inducible DHP production. The BGC was also found in plant-associated Gram-negative bacteria, and in Pseudomonas syringae FF5 we again observed strongly enhanced DHP production upon plant colonization. An ecology-inspired elicitor screen showed that L-valine and brassinosteroid hormones elicit DHP biosynthesis in the plant-beneficial Streptomyces sp. PG2, while L-valine also elicited DHP biosynthesis in S. coelicolor. In vivo experiments confirmed the stimulation of antifungal activity in Streptomyces sp. PG2 by L-valine, while brassinolide mutant plants showed reduced DHP induction. Conversely, neither L-valine nor brassinolide elicited the expression of the DHP BGC in the pathogenic P. syringae, revealing important divergence in the responses to plant signaling, which may reflect selectivity in how endosymbionts and pathogens respond to host cues. Collectively, our data demonstrate that plant colonization can elicit the biosynthetic potential of root-associated microbes, thereby enhancing plant resilience.

microbiology↗

bioRxiv2023

Finding needles in haystacks: identification of novel conserved PETase enzymes in Streptomyces

The rising use of plastic results in an appalling amount of waste which scatters into the environment affecting environmental, animal, and human health. One of these plastics is PET which is mainly used for bottles and textiles. In this research, we investigate the PET degrading ability of the IsPETase homolog ScLipA from Streptomyces coelicolor. Of 96 different Streptomyces strains screened, 18 % were able to degrade the model substrate BHET. Three different variants of lipase A, named ScLipA, S2LipA and S92LipA were identified and analyzed in detail. The lipA gene was deleted from S. coelicolor M145 using CRISPR/Cas9, resulting in reduced BHET degradation. LipA overexpression in the knock-out background significantly enhanced BHET degradation. All three enzymes were expressed in E. coli BL21 for protein purification and biochemical analysis, showing that enzymatic activity most likely resides in a dimeric form of the enzyme. The optimum pH and temperature were determined to be pH 7 and 25 {degrees}C for all three variants. Using these conditions, the activity on BHET and amorphous PET film was investigated. S2LipA efficiently degraded BHET and caused roughening and small indents on the surface of PET films, consistent with PET-degrading activity. The frequent occurrence of the S2LipA variant in Streptomyces suggests an environmental advantage towards the degradation of more hydrophobic substrates such as these polluting plastics in the environment.

microbiology↗