Browsing by Author "Skowronek, Marcin"

Now showing 1 - 8 of 8
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    Bacteria from the midgut of common cockchafer (Melolontha melolontha L.) larvae exhibiting antagonistic activity against bacterial symbionts of entomopathogenic nematodes: isolation and molecular identification
    (MDPI, 2020-01-16) Skowronek, Marcin; Sajnaga, Ewa; Pleszczyńska, Małgorzata; Kazimierczak, Waldemar; Lis, Magdalena; Wiater, Adrian
    The mechanisms of action of the complex including entomopathogenic nematodes of the genera Steinernema and Heterorhabditis and their mutualistic partners, i.e., bacteria Xenorhabdus and Photorhabdus, have been well explained, and the nematodes have been commercialized as biological control agents against many soil insect pests. However, little is known regarding the nature of the relationships between these bacteria and the gut microbiota of infected insects. In the present study, 900 bacterial isolates that were obtained from the midgut samples of Melolontha melolontha larvae were screened for their antagonistic activity against the selected species of the genera Xenorhabdus and Photorhabdus. Twelve strains exhibited significant antibacterial activity in the applied tests. They were identified based on 16S rRNA and rpoB, rpoD, or recA gene sequences as Pseudomonas chlororaphis, Citrobacter murliniae, Acinetobacter calcoaceticus, Chryseobacterium lathyri, Chryseobacterium sp., Serratia liquefaciens, and Serratia sp. The culture filtrate of the isolate P. chlororaphis MMC3 L3 04 exerted the strongest inhibitory effect on the tested bacteria. The results of the preliminary study that are presented here, which focused on interactions between the insect gut microbiota and mutualistic bacteria of entomopathogenic nematodes, show that bacteria inhabiting the gut of insects might play a key role in insect resistance to entomopathogenic nematode pressure.
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    Comparative nanopore sequencing-based evaluation of the midgut microbiota of the summer chafer (Amphimallon solstitiale L.) associated with possible resistance to entomopathogenic nematodes
    (MDPI, 2022-03-15) Sajnaga, Ewa; Skowronek, Marcin; Kalwasińska, Agnieszka; Kazimierczak, Waldemar; Lis, Magdalena; Jach, Monika Elżbieta; Wiater, Adrian
    Root-feeding Amphimallon solstitiale larvae and certain other scarab beetles are the main soil-dwelling pests found in Europe, while entomopathogenic nematodes (EPN) have been used as a biocontrol agent against these species. Our study provides the first detailed characterization of the bacterial community of the midgut in wild A. solstitiale larvae, based on the nanopore sequencing of the 16S rRNA gene. In the whole dataset, we detected 2586 different genera and 11,641 species, with only 83 diverse bacterial genera shared by all studied individuals, which may represent members of the core midgut microbiota of A. solstitiale larvae. Subsequently, we compared the midgut microbiota of EPN-resistant and T0 (prior to EPN exposure) individuals, hypothesizing that resistance to this parasitic infection may be linked to the altered gut community. Compared to the control, the resistant insect microbiota demonstrated lower Shannon and Evenness indices and significant differences in the community structure. Our studies confirmed that the gut microbiota alternation is associated with resistant insects; however, there are many processes involved that can affect the bacterial community. Further research on the role of gut microbiota in insect-parasitic nematode interaction may ultimately lead to the improvement of biological control strategies in insect pest management.
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    Nanopore-sequencing characterization of the gut microbiota of Melolontha melolontha larvae: contribution to protection against entomopathogenic nematodes?
    (MDPI, 2021-03-25) Sajnaga, Ewa; Skowronek, Marcin; Kazimierczak, Waldemar; Ferenc, Karolina; Lis, Magdalena; Wiater, Adrian
    This study focused on the potential relationships between midgut microbiota of the common cockchafer Melolontha melolontha larvae and their resistance to entomopathogenic nematodes (EPN) infection. We investigated the bacterial community associated with control and unsusceptible EPN-exposed insects through nanopore sequencing of the 16S rRNA gene. Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were the most abundant bacterial phyla within the complex and variable midgut microbiota of the wild M. melolontha larvae. The core microbiota was found to include 82 genera, which accounted for 3.4% of the total number of identified genera. The EPN-resistant larvae differed significantly from the control ones in the abundance of many genera belonging to the Actinomycetales, Rhizobiales, and Clostridiales orders. Additionally, the analysis of the microbiome networks revealed different sets of keystone midgut bacterial genera between these two groups of insects, indicating differences in the mutual interactions between bacteria. Finally, we detected Xenorhabdus and Photorhabdus as gut residents and various bacterial species exhibiting antagonistic activity against these entomopathogens. This study paves the way to further research aimed at unravelling the role of the host gut microbiota on the output of EPN infection, which may contribute to enhancement of the efficiency of nematodes used in eco-friendly pest management.
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    Protocol for the identification and antimicrobial susceptibility testing of bacteria isolated from playgrounds
    (2024-04-26) Sadok, Ilona; Łopucki, Rafał; Skowronek, Marcin
    The protocol outlines how to evaluate the occurrence of drug-resistant bacteria on various playground equipment elements and the top layer of the ground. This document describes among others, the procedure for the identification of bacteria isolates using the MALDI-TOF MS Bruker Biotyper platform, and the main steps of the disk diffusion susceptibility test.
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    Protokół do identyfikacji i badania wrażliwości na środki przeciwdrobnoustrojowe bakterii izolowanych z miejskich placów zabaw
    (2024-04-26) Sadok, Ilona; Łopucki, Rafał; Skowronek, Marcin
    Protokół wskazuje w jaki sposób określać obecność lekoopornych szczepów bakterii na różnych elementach wyposażenia i nawierzchni placów zabaw oraz w bioaerozolu. W dokumencie opisano między innymi procedurę identyfikacji izolatów bakterii z wykorzystaniem techniki MALDI-TOF MS oraz oprogramowania Bruker BioTyper, a także główne etapy testu oceny wrażliwości na środki przeciwdrobnoustrojowe metodą dyfuzyjno-krążkową.
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    Screening and molecular identification of bacteria from the midgut of Amphimallon solstitiale larvae exhibiting antagonistic activity against bacterial symbionts of entomopathogenic nematodes
    (MDPI, 2021-11-05) Skowronek, Marcin; Sajnaga, Ewa; Kazimierczak, Waldemar; Lis, Magdalena; Wiater, Adrian
    Entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) are a group of organisms capable of infecting larvae of insects living in soil, including representatives of the family Scarabaeidae. Their insecticidal activity is related to the presence of symbiotic bacteria Xenorhabdus spp. or Photorhabdus spp. in the alimentary tract, which are released into the insect body, leading to its death caused by bacterial toxins and septicemia. Although the antibacterial activities of symbionts of entomopathogenic nematodes have been well described, there is insufficient knowledge of the interactions between these bacteria and microorganisms that naturally inhabit the alimentary tract of insects infested by nematodes. In this study, 900 bacterial strains isolated from midgut samples of Amphimallon solstitiale larvae were tested for their antagonistic activity against the selected five Xenorhabdus and Photorhabdus species. Cross-streak tests showed significant antibacterial activity of 20 isolates. These bacteria were identified as Bacillus [Brevibacterium] frigoritolerans, Bacillus toyonensis, Bacillus wiedmannii, Chryseobacterium lathyri, Chryseobacterium sp., Citrobacter murliniae, Enterococcus malodoratus, Paenibacillus sp., Serratia marcescens and Serratia sp. Since some representatives of the intestinal microbiota of A. solstitiale are able to inhibit the growth of Xenorhabdus and Photorhrhabdus bacteria in vitro, it can be assumed that this type of bacterial interaction may occur at certain stages of insect infection by Steinernema or Heterorhabditis nematodes.
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    Steinernema poinari (Nematoda: Steinernematidae): a new symbiotic host of entomopathogenic bacteria Xenorhabdus bovienii
    (Springer, 2018-06-19) Sajnaga, Ewa; Kazimierczak, Waldemar; Skowronek, Marcin; Lis, Magdalena; Skrzypek, Tomasz; Waśko, Adam
    Three strains of symbiotic bacteria were isolated from an entomopathogenic nematode Steinernema poinari retrieved from soil in eastern Poland. Using 16S rDNA, recA, gltX, gyrB, and dnaN gene sequences for phylogenetic analysis, these strains were shown to belong to the species Xenorhabdus bovienii. The nucleotide identity between the studied S. poinari microsymbionts and other X. bovienii strains calculated for 16S rDNA and concatenated sequences of four protein-coding genes was 98.7–100% and 97.9–99.5%, respectively. The phenotypic properties of the isolates also supported their close phylogenetic relationship with X. bovienii. All three tested X. bovienii strains of diffrent Steinernema clade origin supported the recovery of infective juveniles and subsequent development of the nematode population. However, the colonization degree of new infective juvenile generations was signifiantly affcted by the bacterial host donor/recipient. The colonization degree of infective juveniles reared on bacterial symbionts deriving from a non-cognate clade of nematodes was extremely low, but proved the possible host-switching between non-related Steinernema species.
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    Steinernema sandneri n. sp. (Rhabditida: Steinernematidae), a new entomopathogenic nematode from Poland
    (Exeley, 2021-05-21) Lis, Magdalena; Sajnaga, Ewa; Skowronek, Marcin; Wiater, Adrian; Rachwał, Kamila; Kazimierczak, Waldemar
    A new species of entomopathogenic nematodes, Steinernema sandneri n. sp., was recovered by baiting from Poland. Its morphological traits indicate that the new species is a member of the feltiae-kraussei group. A body length of 843 (708-965) μm., a more anterior position of excretory pore (56 μm), and the lower D% value (40 vs. >46) discriminate this species from most of the other group members. The first-generation males of S. sandneri n. sp. can be distinguished from the other clade members by a 60 μm long spicule, a relatively long gubernaculum (GS%=79), and the position of the excretory pore (80 μm). Phylogenetic analysis of the ITS rDNA, D2D3 of 28S rDNA, and cox1 sequences confirmed that S. sandneri n. sp. is a new species of the feltiae-kraussei group, closely related to S. kraussei and S. silvaticum.