LIMLIN, A NOVEL LEGUMINOUS PEROXIDASE WITH ANTIFUNGAL ACTIVITY FROM PHASEOLUS LIMENSIS

Production of two novel antifungal peroxidase isoenzymes from Tabernaemontana catharinensis using a bubble-column bioreactor

Plant peroxidases are enzymes with significant antioxidative properties and catalytic versatility, making them valuable for various applications in biotechnology. However, their commercial use is often constrained by inefficient production methods. In this study, we isolated and characterized two peroxidase isoenzymes, TcPOX-I and TcPOX-II, from Tabernaemontana catharinensis using scalable plant cell culture techniques, offering a sustainable alternative to traditional enzyme production methods. By successfully scaling up cultures from flasks to a 3 L bubble-column bioreactor equipped with optimized aeration, aseptic conditions, and real-time monitoring, we enhanced peroxidase production efficiency. Although biomass in the bioreactor was lower than in flask cultures, peroxidase secretion per unit of mass was higher, demonstrating that the bioreactor conditions favored enzyme production over cell proliferation. TcPOX-I and II were isolated via size-exclusion chromatography, exhibiting molecular masses of approximately 34 kDa and isoelectric points of 6.7 and 6.8, respectively. Amino acid sequencing confirmed high homology with known plant peroxidases, while carbohydrate analysis revealed about 4% carbohydrate content, classifying both as glycoproteins. Notably, their enzymatic activity was unaffected by deglycosylation, suggesting potential for heterologous expression. Both isoenzymes displayed optimal activity at pH 6.5 using guaiacol as the substrate, along with unique thermal stability and metal ion response profiles. These properties suggest promising applications in biosensing, biocatalysis, and environmental remediation. Importantly, TcPOX-I and TcPOX-II exhibited concentration-dependent antifungal activity against Candida albicans and Penicillium sp., highlighting their potential as natural antifungal agents. Overall, this work demonstrates the scalable bioreactor production of two, deglycosylation-tolerant peroxidases from T. catharinensis, paving the way for their exploitation in diverse biotechnological applications.

Increased Levels of Antinutritional and/or Defense Proteins Reduced the Protein Quality of a Disease-Resistant Soybean Cultivar

The biochemical and nutritional attributes of two soybean (Glycine max (L.) Merr.) cultivars, one susceptible (Seridó) and the other resistant (Seridó-RCH) to stem canker, were examined to assess whether the resistance to pathogens was related to levels of antinutritional and/or defense proteins in the plant and subsequently affected the nutritional quality. Lectin, urease, trypsin inhibitor, peroxidase and chitinase activities were higher in the resistant cultivar. Growing rats were fed with isocaloric and isoproteic diets prepared with defatted raw soybean meals. Those on the Seridó-RCH diet showed the worst performance in terms of protein quality indicators. Based on regression analysis, lectin, trypsin inhibitor, peroxidase and chitinase appear to be involved in the resistance trait but also in the poorer nutritional quality of Seridó-RCH. Thus, the development of cultivars for disease resistance may lead to higher concentrations of antinutritional compounds, affecting the quality of soybean seeds. Further research that includes the assessment of more cultivars/genotypes is needed.

Plant antifungal proteins and their applications in agriculture

Fungi are far more complex organisms than viruses or bacteria and can develop numerous diseases in plants that cause loss of a substantial portion of the crop every year. Plants have developed various mechanisms to defend themselves against these fungi which include the production of low-molecular-weight secondary metabolites and proteins and peptides with antifungal activity. In this review, families of plant antifungal proteins (AFPs) including defensins, lectins, and several others will be summarized. Moreover, the application of AFPs in agriculture will also be analyzed.