The immunostimulatory role of an dominated gut microbiota in host protection against bacterial and fungal pathogens in larvae.

Understanding the intricate interplay between the gut microbiota and the immune response in insects is crucial, given its diverse impact on the pathogenesis of various microbial species. The microbiota's modulation of the host immune system is one such mechanism, although its complete impact on immune responses remains elusive. This study investigated the tripartite interaction between the gut microbiota, pathogens, and the host's response in larvae reared under axenic (sterile) and conventional (non-sterile) conditions.

Minor impact of probiotic bacteria and egg white on growth, microbial composition, and pathogen infection.

The industrial rearing of the yellow mealworm () for feed and food purposes on agricultural by-products may expose larvae and adults to entomopathogens used as biocontrol agents in crop production. Bacterial spores/toxins or fungal conidia from species such as or could affect the survival and growth of insects. Therefore, the aim of this study was to investigate the potential benefits of a wheat bran diet supplemented with probiotic bacteria and dried egg white on larval development and survival and its effects on the gut microbiome composition.

Impact and Persistence of in Larvae and Feed under Optimal and Stressed Mass Rearing Conditions.

Industrial insect mass rearing aims to produce quality insects under safe sanitary conditions which can be compromised by pathogens and abiotic stressors. Therefore, knowledge on pathogen persistence, virulence and means of detection is of importance. This study focuses on the opportunistic pathogen () as a possible candidate to reveal sanitary issues in () breeding.

Plastic biodegradation: Do Larvae Bioassimilate Polyethylene? A Spectral Histology Approach Using Isotopic Labeling and Infrared Microspectroscopy.

Environmental pollution by the nearly nonbiodegradable polyethylene (PE) plastics is of major concern; thus, organisms capable of biodegrading PE are required. The larvae of the Greater Wax Moth, (Gm), were identified as a potential candidate to digest PE. In this study, we tested whether PE was metabolized by Gm larvae and could be found in their tissues.

Laser capture microdissection to study Bacillus cereus iron homeostasis gene expression during Galleria mellonella in vivo gut colonization.

 is a Gram-positive opportunistic pathogen closely related to the entomopathogen, , both of which are involved in intestinal infections. Iron is an essential micronutrient for full growth and virulence of pathogens during infection. However, little is known about iron homeostasis during gut infection.

Use and misuse of FTIR spectroscopy for studying the bio-oxidation of plastics.

Due to massive production, inefficient waste collection, and long lives, plastics have become a source of persistent pollution. Biodegradation is explored as an environmentally friendly remediation method for removing plastics from the environment. Microbial and animal biodegradation methods have been reported in the literature for various plastics.

MogR Is a Ubiquitous Transcriptional Repressor Affecting Motility, Biofilm Formation and Virulence in .

Flagellar motility is considered an important virulence factor in different pathogenic bacteria. In the transcriptional repressor MogR regulates motility in a temperature-dependent manner, directly repressing flagellar- and chemotaxis genes. The only other bacteria known to carry a homolog are members of the group, which includes motile species such as and as well as the non-motile species , and Furthermore, the main motility locus in group bacteria, carrying the genes for flagellar synthesis, appears to be more closely related to than to , which belongs to a separate phylogenetic group of Bacilli and does not carry a ortholog.

CbpA is a collagen binding cell surface protein under c-di-GMP control.

Cyclic diguanylate (c-di-GMP) signalling affects several cellular processes in group bacteria including biofilm formation and motility, and CdgF was previously identified as a diguanylate cyclase promoting biofilm formation in C-di-GMP can exert its function as a second messenger via riboswitch binding, and a functional c-di-GMP-responsive riboswitch has been found upstream of in various group strains. Protein signature recognition predicted CbpA to be a cell wall-anchored surface protein with a fibrinogen or collagen binding domain. The aim of this study was to identify the binding ligand of CbpA and the function of CbpA in cellular processes that are part of the group c-di-GMP regulatory network.

Heme Uptake in Evidenced by a New Energy Coupling Factor (ECF)-Like Transport System.

is a nonpathogenic lactic acid bacterium and a natural inhabitant of meat ecosystems. Although red meat is a heme-rich environment, does not need iron or heme for growth, although it possesses a heme-dependent catalase. Iron incorporation into from myoglobin and hemoglobin was previously shown by microscopy and the genome reveals the complete equipment for iron and heme transport.

A Chitin-Binding Protein is Involved in Insect Peritrophic Matrix Adhesion and Takes Part in the Infection Process.

(Bt) is used for insect pest control, and its larvicidal activity is primarily attributed to Cry toxins. Other factors participate in infection, and limited information is available regarding factors acting on the peritrophic matrix (PM). This study aimed to investigate the role of a Bt chitin-binding protein (CBPA) that had been previously shown to be expressed at pH 9 and could therefore be expressed in the alkaline gut of lepidopteron larvae.

Spores and Vegetative Bacteria: Infection Capacity and Role of the Virulence Regulon PlcR Following Intrahaemocoel Injection of .

is an invertebrate pathogen that produces insecticidal crystal toxins acting on the intestinal barrier. In the larvae infection model, toxins from the PlcR virulence regulon contribute to pathogenicity by the oral route. While is principally an oral pathogen, bacteria may also reach the insect haemocoel following injury of the cuticle.

CalY is a major virulence factor and a biofilm matrix protein.

The extracellular biofilm matrix often contains a network of amyloid fibers which, in the human opportunistic pathogen Bacillus cereus, includes the two homologous proteins TasA and CalY. We show here, in the closely related entomopathogenic species Bacillus thuringiensis, that CalY also displays a second function. In the early stationary phase of planktonic cultures, CalY was located at the bacterial cell-surface, as shown by immunodetection.

DltX of Is Essential for D-Alanylation of Teichoic Acids and Resistance to Antimicrobial Response in Insects.

The operon of Gram-positive bacteria is required for the incorporation of D-alanine esters into cell wall-associated teichoic acids (TAs). Addition of D-alanine to TAs reduces the negative charge of the cell envelope thereby preventing cationic antimicrobial peptides (CAMPs) from reaching their target of action on the bacterial surface. In most gram-positive bacteria, this operon consists of five genes but the involvement of the first ORF () encoding a small protein of unknown function, has never been investigated.

Correction: Necrotrophism Is a Quorum-Sensing-Regulated Lifestyle in Bacillus thuringiensis.

[This corrects the article DOI: 10.1371/journal.ppat.

Comparative genomics of extrachromosomal elements in Bacillus thuringiensis subsp. israelensis.

Bacillus thuringiensis subsp. israelensis is one of the most important microorganisms used against mosquitoes. It was intensively studied following its discovery and became a model bacterium of the B.

Heme interplay between IlsA and IsdC: Two structurally different surface proteins from Bacillus cereus.

Background: Iron is an essential element for bacterial growth and virulence. Because of its limited bioavailability in the host, bacteria have adapted several strategies to acquire iron during infection. In the human opportunistic bacteria Bacillus cereus, a surface protein IlsA is shown to be involved in iron acquisition from both ferritin and hemoproteins.

The social biology of quorum sensing in a naturalistic host pathogen system.

Many microorganisms cooperate by secreting products that are commonly available to neighboring cells. These "public goods" include autoinduced, quorum-sensing (QS) molecules and the virulence factors activated by these signals. Public goods cooperation is exploitable by cheaters, cells that avoid the costs of production but gain an advantage by freeloading on the products of others.

SecDF as part of the Sec-translocase facilitates efficient secretion of Bacillus cereus toxins and cell wall-associated proteins.

The aim of this study was to explore the role of SecDF in protein secretion in Bacillus cereus ATCC 14579 by in-depth characterization of a markerless secDF knock out mutant. Deletion of secDF resulted in pleiotropic effects characterized by a moderately slower growth rate, aberrant cell morphology, enhanced susceptibility to xenobiotics, reduced virulence and motility. Most toxins, including food poisoning-associated enterotoxins Nhe, Hbl, and cytotoxin K, as well as phospholipase C were less abundant in the secretome of the ΔsecDF mutant as determined by label-free mass spectrometry.

An insect gut environment reveals the induction of a new sugar-phosphate sensor system in Bacillus cereus.

Bacteria survive under various conditions by sensing stimuli triggering specific adaptive physiological responses, which are often based on membrane-integrated sensors connected to a cytoplasmic regulator. Recent studies reveal that mucus glycans may act as signal molecules for two-component systems involved in intestinal colonization. Bacillus cereus, a human and insect opportunistic pathogen was used to identify bacterial factors expressed in an insect gut infection model.

The insect Galleria mellonella as a powerful infection model to investigate bacterial pathogenesis.

The study of bacterial virulence often requires a suitable animal model. Mammalian models of infection are costly and may raise ethical issues. The use of insects as infection models provides a valuable alternative.

How the insect pathogen bacteria Bacillus thuringiensis and Xenorhabdus/Photorhabdus occupy their hosts.

Insects are the largest group of animals on earth. Like mammals, virus, fungi, bacteria and parasites infect them. Several tissue barriers and defense mechanisms are common for vertebrates and invertebrates.

A multicomponent sugar phosphate sensor system specifically induced in Bacillus cereus during infection of the insect gut.

Using a previously developed Bacillus cereus in vivo expression technology (IVET) promoter trap system, we showed that spsA, a gene of unknown function, was specifically expressed in the larval gut during infection. Search for gut-related compounds inducing spsA transcription identified glucose-6-phosphate (G6P) as an activation signal. Analysis of the spsA-related 5-gene cluster indicated that SpsA is part of a new sugar phosphate sensor system composed of a 2-component system (TCS) encoded by spsR and spsK, and 2 additional downstream genes, spsB and spsC.

Necrotrophism is a quorum-sensing-regulated lifestyle in Bacillus thuringiensis.

How pathogenic bacteria infect and kill their host is currently widely investigated. In comparison, the fate of pathogens after the death of their host receives less attention. We studied Bacillus thuringiensis (Bt) infection of an insect host, and show that NprR, a quorum sensor, is active after death of the insect and allows Bt to survive in the cadavers as vegetative cells.