Biology subjects

Zanchi, C.

Publications and source records attributed to Zanchi, C..

6 recordsLinked to original sources

bioRxiv2025

Fermentation of Agricultural By-products and Zinc Supplementation: A Synergistic Approach to Mealworm Microbiome Optimization

The increasing world population has put pressure on food industry to swiftly come up with initiatives that can sustain an increase in the demand for food, which have led to environmentally unsustainable practices. Insects, such as Tenebrio molitor (TM) larvae, have been widely proposed as sustainable alternative sources of protein with less environmental footprint. Insects can be reared with diets featuring low-cost agricultural side-streams, promoting circular economical practices, which can also be fermented to promote the development of probiotic microbiota. The inclusion of probiotics in the diets of insects during rearing has recently been explored to mitigate potential exposure to pathogens, potentially serving as alternatives to antibiotics. The focus of this study was the fermentation of spinach to naturally develop complex probiotic populations to enrich the diet of mealworms, promoting host health, thus resulting in a more nutritious food/feed source, featuring a safer microbiome profile. Sequencing revealed that fermented spinach had increased lactic acid bacteria (LAB), while repressing Pseudomonas. LAB species have been acknowledged and used as probiotics, whereas Pseudomonas populations are often associated with opportunistic resistant infections. Moreover, zinc is an essential element for bacterial microbiomes of many organisms, including insects. As the effects of dietary zinc on insect gut microbiome have been scarcely investigated, we have supplemented our formulated diets with this trace element and fed it to TM larvae for 35 days. While various diet compositions did not affect mealworm mortality, larvae fed spinach-based and zinc-rich diets gained less weight than that of control. Furthermore, higher dosage of zinc-supplementation resulted in significantly higher accumulation in TM larvae and a lower bioaccumulation factor. Sequencing of larvae fed diets supplemented with fermented spinach revealed increased presence of probiotic-associated genera, Lactococcus and Weissella. It was also found that supplementing diets with spinach and zinc significantly modulated the microbiome of larvae.

microbiology↗

bioRxiv2025

Speed Matters: Accelerated Pharmacokinetics Reduce Persisters in Escherichia coli

Persister cells are bacterial cells that form small subpopulations and are refractory to antimicrobials. Importantly, those cells can cause the relapse of an infection and also provide a starting point for antimicrobial resistance evolution. By now, several mechanisms of persister formation have been studied. For example, it has been shown that a short exposure to sublethal concentrations of antimicrobials can induce persister formation. Given this, we hypothesised that the pharmacokinetics, the temporal changes of drug concentrations under treatment, could impact persister formation. We predicted that the longer bacteria spend under sublethal drug concentrations, the more persisters would form. Using a set-up with small chemostats and the antimicrobial peptide Pexiganan, we indeed found that faster pharmacokinetics resulted in lower persister numbers compared to slower pharmacokinetics. This finding provides a proof of principle that pharmacokinetics, which can be influenced by treatment procedures, has consequences for persister formation. Our results suggest that faster pharmacokinetics could be useful to minimize persister numbers and hence to lower the risks of relapse or resistance evolution.

evolutionary biology↗

bioRxiv2025

Immune-mediated indirect interaction between gut microbiota and bacterial pathogens

BackgroundOrganism survival depends on the ability to orchestrate interactions between the host immune system and gut microbiota in response to pathogenic infections. These tripartite interactions shape pathogen virulence evolution. A key regulator of the immune system and, hence, bipartite interactions (in insects) is the immune deficiency (Imd) pathway, which modulates gut microbiota and pathogens by synthesizing antimicrobial peptides (AMPs). However, whether Imd-dependent AMPs mediate indirect interactions between gut microbiota and pathogens in a tripartite context remains unclear. Using RNAi-mediated knockdown of Tenebrio molitor Relish (TmRelish), we hypothesized that Imd-dependent AMPs influence indirect interaction between Providencia burhodogranaria_B infection and the gut microbiota. ResultsWhile TmRelish-knockdown altered bipartite interactions, disrupting gut microbiota load and composition and increasing pathogen load and virulence through higher host mortality, it did not support our tripartite hypothesis. Instead of Imd-dependent AMPs, gut microbiota and pathogen were influenced by Imd-independent AMPs expression, suggesting alternative regulatory pathways. Nevertheless, our investigations of tripartite interactions showed a positive effect of P. b_B infection on gut microbiota load, while survival analysis further revealed a negative effect of gut microbiota on pathogens infection, suggesting microbiota- mediated immune priming. ConclusionsThese findings suggest that while Imd-dependent AMPs may not mediate tripartite interactions, microbiota-host interactions, such as microbiota-mediated immune priming and changes in microbiota load, can shape infection outcomes. These effects on infection outcomes almost certainly exert important selective pressures on the evolution of bacterial virulence.

immunology↗

bioRxiv2024

The evolution of antimicrobial peptide resistance in Pseudomonas aeruginosa is severely constrained by random peptide mixtures

The prevalence of antibiotic-resistant pathogens has become a major threat to public health, requiring swift initiatives for discovering new strategies to control bacterial infections. Hence, antibiotic stewardship and rapid diagnostics, but also the development, and prudent use, of novel effective antimicrobial agents are paramount. Ideally, these agents should be less likely to select for resistance in pathogens than currently available conventional antimicrobials. The usage of antimicrobial Peptides (AMPs), key components of the innate immune response, and combination therapies, have been proposed as strategies to diminish the emergence of resistance. Herein, we investigated whether newly developed random antimicrobial peptide mixtures (RPMs) can significantly reduce the risk of resistance evolution in vitro to that of single sequence AMPs, using the ESKAPE pathogen Pseudomonas aeruginosa (P. aeruginosa) as a model Gram-negative bacterium. Infections of this pathogen are difficult to treat due the inherent resistance to many drug classes, enhanced by the capacity to form biofilms. P. aeruginosa was experimentally evolved in the presence of AMPs or RPMs, subsequentially assessing the extent of resistance evolution and cross-resistance/collateral sensitivity between treatments. Furthermore, the fitness costs of resistance on bacterial growth were studied, and whole-genome sequencing used to investigate which mutations could be candidates for causing resistant phenotypes. Lastly, changes in the pharmacodynamics of the evolved bacterial strains were examined. Our findings suggest that using RPMs bears a much lower risk of resistance evolution compared to AMPs and mostly prevents cross-resistance development to other treatments, while maintaining (or even improving) drug sensitivity. This strengthens the case for using random cocktails of AMPs in favour of single AMPs, against which resistance evolved in vitro, further providing an alternative to classic antibiotics worth pursuing.

microbiology↗

bioRxiv2019

Relationship between early body condition, energetic reserves and fitness in an iteroparous insect

O_LIInsects are core actors for the balance of many earth ecosystems, as well as an alternative source of food and feed with a low ecological footprint. A comprehensive understanding of their life history requires reliable tools. Body condition constitutes the amount of energy reserves available to a fitness trait after maintenance costs have been accounted for. Body condition is standardly estimated using Body Condition Indexes (BCIs) in vertebrates. In insects the relevance of BCIs is frequently questioned on the basis that they might not accurately reflect neither energy reserves nor fitness.. However, to date no study has tested whether the very concept of body condition is relevant in insects, i.e. whether BCIs accurately reflect the relative energy reserves allocated to fitness traits. C_LIO_LIWe propose that the relevance of using BCIs in insects depends on whether their structural size has a fitness cost. If on the contrary insects only benefit from a larger body size, a simple measurement of body size or mass will predict fitness, but not a BCI. We experimentally manipulated food availability at the larval and adult stage and used total fecundity of females as a fitness proxy of Tenebrio molitor, an important model in physiology, ecology and evolution, and one of the first insects to be considered as a source of food and feed. C_LIO_LIOur results support three key assumptions of the relevance of BCIs in insects: (i) a valid BCI correlated with energy reserves corrected for a given size (i.e. relative energy reserves) and not with absolute measures of energy reserves; (ii) both structural size and body condition positively predict different components of fitness; and, (iii) the effect of body condition was dependent on resource availability, whereby its effect was only apparent and large when food was unrestricted at the larval stage and restricted at the adult stage. C_LIO_LIOverall we demonstrate the relevance of using BCIs in insects. Their use should be generalized to improve fitness readouts in evolution, ecological and physiological studies, as well as improve their husbandry for commercial purposes. C_LI

ecology↗

bioRxiv2018

A constitutively expressed antifungal peptide protects Tenebrio molitor during a natural infection by the entomopathogenic fungus Beauveria bassiana.

Antimicrobial peptides have been well studied in the context of bacterial infections. Antifungal peptides have received comparatively less attention. Fungal pathogens of insects and their hosts represent a unique opportunity to study host-pathogen interactions due to the million of years of co-evolution they share. In this study, we investigated role of a constitutively expressed thaumatin-like peptide with antifungal activity expressed by the mealworm beetle Tenebrio molitor, named Tenecin 3, during a natural infection with the entomopathogenic fungus Beauveria bassiana. We monitored the effect of the expression of Tenecin 3 on the survival of infected hosts as well as on the progression of the fungal infection inside the host. Finally, we tested the activity of Tenecin 3 against B. bassiana. These findings could help improving biocontrol strategies and help understanding the evolution of antifungal peptides as a defense mechanism.

immunology↗