A method for high-frequency transformation of Trichoderma viride

Bioprospecting Trichoderma: A Systematic Roadmap to Screen Genomes and Natural Products for Biocontrol Applications

Natural products derived from microbes are crucial innovations that would help in reaching sustainability development goals worldwide while achieving bioeconomic growth. Trichoderma species are well-studied model fungal organisms used for their biocontrol properties with great potential to alleviate the use of agrochemicals in agriculture. However, identifying and characterizing effective natural products in novel species or strains as biological control products remains a meticulous process with many known challenges to be navigated. Integration of recent advancements in various "omics" technologies, next generation biodesign, machine learning, and artificial intelligence approaches could greatly advance bioprospecting goals. Herein, we propose a roadmap for assessing the potential impact of already known or newly discovered Trichoderma species for biocontrol applications. By screening publicly available Trichoderma genome sequences, we first highlight the prevalence of putative biosynthetic gene clusters and antimicrobial peptides among genomes as an initial step toward predicting which organisms could increase the diversity of natural products. Next, we discuss high-throughput methods for screening organisms to discover and characterize natural products and how these findings impact both fundamental and applied research fields.

In vitro flow cytometry-based screening platform for cellulase engineering

Ultrahigh throughput screening (uHTS) plays an essential role in directed evolution for tailoring biocatalysts for industrial applications. Flow cytometry-based uHTS provides an efficient coverage of the generated protein sequence space by analysis of up to 10⁷ events per hour. Cell-free enzyme production overcomes the challenge of diversity loss during the transformation of mutant libraries into expression hosts, enables directed evolution of toxic enzymes, and holds the promise to efficiently design enzymes of human or animal origin. The developed uHTS cell-free compartmentalization platform (InVitroFlow) is the first report in which a flow cytometry-based screened system has been combined with compartmentalized cell-free expression for directed cellulase enzyme evolution. InVitroFlow was validated by screening of a random cellulase mutant library employing a novel screening system (based on the substrate fluorescein-di-β-D-cellobioside), and yielded significantly improved cellulase variants (e.g. CelA2-H288F-M1 (N273D/H288F/N468S) with 13.3-fold increased specific activity (220.60 U/mg) compared to CelA2 wildtype: 16.57 U/mg).

Enhanced frequency of Beauveria bassiana blastospore transformation by restriction enzyme-mediated integration and electroporation

The techniques of restriction enzyme-mediated integration (REMI) and electroporation (EP) were applied for the first time to improving the blastospore transformation of fungal biocontrol agent Beauveria bassiana for higher frequency. The blastospores from < or =24 h incubation in glucose-mineral medium after shaking conidia for 48 h in Subouraud dextrose broth were found most competent for integrating 1 microg plasmid DNA vectoring the phosphinothricin (PPT) resistance gene bar in 360 microL reaction system containing 100 U HindIII or XbaI. Such blastospores were also most suitable for EP transformation at the optimized field strength of 10 kV cm(-1). The optimized REMI and EP generated averagely 39 and 53 transformants microg(-1) plasmid DNA whereas polyethylene glycol (PEG) integration yielded only 22. All transformants grew well on Czapek's agar containing 400 microg PPT mL(-1) after three rounds of cultivation on the same agar excluding PPT but their parental strain showed no resistance. The target gene inserted into the genomes of 10 transformants randomly taken from REMI or EP transformation was consistently detected by both PCR and Southern blotting. Compared to the PEG integration, REMI and EP enhanced the frequency of the blastospore transformation by 73 and 137%, respectively.

Karyotyping of Candida albicans and Candida glabrata isolates from recurrent vaginal infections by pulsed-field gel electrophoresis

In the present study, 16 women with recurrent vulvovaginal candidiasis (RVVC) due to Candida albicans and Candida (Torulopsis) glabrata were followed for a period of 4 to 12 months, and 36 vaginal isolates were evaluated by pulsed-field gel electrophoresis (PFGE). Eleven women were infected by C. albicans and 5 by C. glabrata. Three electrophoretic karyotypes of C. albicans and 3 of C. glabrata were identified throughout the follow-up. All patients but one was infected with the same karyotype of C. albicans or C. glabrata during the follow-up period. Two different karyotypes of C. glabrata were identified in one patient in the course of 12 months. The results confirmed the diversity of the karyotypes of C. albicans and C. glabrata causing vulvovaginitis, and demonstrated the persistence of colonization with the same strain over different periods of time despite therapy (15/16 women).

Characterization of the extracellular enzyme systems of Trichoderma viride AH124

A mycoparasitic Trichoderma viride strain was investigated for the production of extracellular enzymes important in antagonism, by using natural and chromogenic substrates. Some of these enzymes, such as beta-1,3-glucanases, and low levels of proteases were produced constitutively. Under inductive conditions, the measurable activities of beta-1,3-glucanase, protease and aspecific chitinase increased, while for the proteases and beta-1,3-glucanases, the levels depended on both the nitrogen and the carbon source. Gel filtration chromatography revealed at least 4 beta-1,3-glucanases, 6 proteases, 2 beta-glucosidases and 1 beta-1,4-N-acetyl-glucosaminidase izoenzyme under inductive conditions.

Biological control of agricultural pests by filamentous fungi

Agricultural use of chemical pesticides has polluted the environment and resulted in resistance among the target organisms. The chemical strategies of pest control are dangerous to both the nontarget organisms in natural habitats and human health. Biological control is an attractive less dangerous possibility for controlling plant pathogens.Some methods of biological control are becoming now commercially available against plant parasitic fungi, nematods and insects. Among filamentous fungi many candidates with biocontrol potential can be found. Fungal biocontrol agents are less effective and reliable than the synthetic pesticides therefore their use in the agricultural practice requires genetic improvement.