Search Results (52)

Studying marine Actinobacteria across ecological niches is essential for discovering novel natural products and understanding microbial interactions. In this study, we investigated the diversity of Actinobacteria associated with five Arctic marine invertebrates using both selective culture-based techniques and culture-independent methods. Additionally, we investigated bacteria–bacteria interactions in an advanced high-throughput co-cultivation assay. We isolated 25 Actinobacteria and classified them into 15 genera, with 53% of the isolates recovered from the sponge Halichondria panicea. In contrast, metabarcoding revealed a high diversity of Actinobacteria, with Chlamys islandica exhibiting the highest uniqueness of Amplicon Sequence Variants (ASVs), as 21.76% of its ASVs were found exclusively in this species. Similarly, not only did Dendrobeania sp. and Tricellaria ternata display notable levels of unique ASVs at 19.91% and 18.06%, respectively, they also shared 17.74% of ASVs, demonstrating a greater similarity in their microbial communities than between more distantly related hosts. A variety of microbial interactions were observed on solid medium, including both cooperative and antagonistic relationships, using the co-cultivation assay. These included inter- and intra-Actinobacteria interactions, as well as interactions with human pathogenic bacteria. The duration of co-cultivation and the physical proximity of bacterial partners influenced the extent of these interactions. Full article

Organic farming is widely recognized as a promising practice for sustainable agriculture, yet its long-term ecological impacts remain insufficiently investigated. In this study, we evaluated these impacts by comparing heavy metal concentrations, soil invertebrate communities, and microbial profiles between long-term organic and conventional farming systems. A comparative analysis was conducted on 24 plot soils from two paired organic and conventional farm systems in Beijing, each managed continuously for over 20 years. Our results revealed that soils under organic management consistently contained 10.8% to 73.7% lower heavy metals, along with reduced geo-accumulation indices (I_geo, a standardized metric for soil contamination assessment), indicating decreased contamination risks. In terms of soil fauna, while conventional soils showed higher Collembola abundance, organic farming significantly enhanced Collembola richness and diversity by 20.6% to 55.0%. Microbial sequencing likewise revealed enhanced richness and diversity of bacteria and fungi in organic soils. These microbial communities also displayed shifts in dominant taxa and more stable co-occurrence networks under organic management. Principal component analysis and Mantel tests identified soil pH and nutrients as key drivers of soil biodiversity, while heavy metals also imposed negative influences. Collectively, these findings demonstrate that long-term organic farming not only mitigates environmental risks associated with soil contaminants but also promotes belowground ecological integrity by supporting biodiversity of soil fauna and microbiota. This study highlights the ecological significance of sustained organic practices and provides critical insights for advancing sustainable agricultural developments. Full article

Deep-sea chemosynthetic ecosystems, including cold seeps and hydrothermal vents, are widely spread in global oceans. Campylobacterota are important primary producers in deep-sea hydrothermal vents and serve as a vital food source for local invertebrates. However, the nutrients that these bacteria can provide to their hosts are unclear. To date, research on Campylobacterota in cold seeps is very limited. Consequently, little is known about the biological features and ecological potential of Campylobacterota in cold seeps. In the present work, we examined the diversity, growth, metabolic characteristics, and nutrient production of Campylobacterota in a deep-sea cold seep. Over 1000 Campylobacterota ASVs, especially autotrophic Sulfurovum and Sulfurimonas, were identified. By optimizing the culture medium, 9 Sulfurovum and Sulfurimonas strains were isolated, including three potentially novel species. Two novel species were characterized and found to exhibit unique morphological features. These two novel strains possessed complete reverse tricarboxylic acid pathways. One novel strain, FCS5, was a psychrotolerant autotroph with denitrification and phosphorus-removing capacity. FCS5 could grow in the absence of vitamins. Consistently, metabolomics and transcriptome analyses indicated that FCS5 produced multiple vitamins, which regulated the expressions of a large number of genes associated with carbon fixation and multiple-nutrient synthesis. Besides vitamins, autotrophic Campylobacterota also produced abundant free amino acids, fatty acids (short-chain, medium, and long-chain), and proteins. This study indicates that the cold seep abounds with Campylobacterota, which are capable of providing various nutrients for the chemosynthetic ecosystem. In addition, these bacteria may have wide applications, such as in wastewater treatment and carbon emission reduction. Full article

Antimicrobial peptides (AMPs) constitute a large and diverse group of molecules with antibacterial, antifungal, antiviral, antiprotozoan, and anticancer activity. In animals, they are key components of innate immunity involved in fighting against various pathogens. Proline-rich (Pr) AMPs are characterized by a high content of proline (and arginine) residues that can be organized into Pro-Arg-Pro motifs. Such peptides have been described in many invertebrates (annelids, crustaceans, insects, mollusks) and some vertebrates (mammals). The main objective of this review is to present the diversity of invertebrate PrAMPs, which are associated with the presence of cysteine-rich domains or whey acidic protein domains in the molecular structure, in addition to the presence of characteristic proline-rich regions. Moreover, PrAMPs can target intracellular structures in bacteria, e.g., 70S ribosomes and/or heat shock protein DnaK, leading to the inhibition of protein synthesis and accumulation of misfolded polypeptides in the cell. This unique mechanism of action makes it difficult for pathogens to acquire resistance to this type of molecule. Invertebrate PrAMPs have become the basis for the development of new synthetic analogues effective in combating pathogens. Due to their great diversity, new highly active molecules are still being searched for among PrAMPs from invertebrates. Full article

Invertebrates, including Asellidae, are part of the natural ecosystem of the drinking water distribution system (DWDS) and are known to cause a nuisance to consumers. In addition, recently, the potential role of the species Asellus aquaticus (L. 1758) in the regrowth of Aeromonas bacteria was published. Aeromonas is included in the Dutch drinking water guidelines as a process parameter, and the guideline values are regularly exceeded. Although neither A. aquaticus nor Aeromonas is associated with health risks, the Evides drinking water utility shows a strong interest in the possible reasons for these exceedances and possible control measures. In surface waters, Asellidae feed mainly on decaying leaves that are abundantly present. These food sources are not present in the DWDS. Therefore, we determined suitable food sources for A. aquaticus in the DWDS. Laboratory experiments show that A. aquaticus individuals survive on biofilm on pipe wall material and loose deposits (sediments) collected from DWDS. Growth and survival rates on these loose deposits were even higher than on the positive control (decaying leaves). As the basis of these loose deposits is inorganic (iron deposits, sand, and pipe particles), the organic matter (living and decaying bacteria, protozoans, fungi, and invertebrates) must be their substrate. These experiments validate hypotheses that Asellidae can grow and survive on organic matter in deposits in DWDS. Full article

Wolbachia bacteria (phylum Proteobacteria) are ubiquitous intracellular parasites of diverse invertebrates. In insects, coevolution has forged mutualistic associations with Wolbachia species, influencing reproduction, immunity, development, pathogen resistance, and overall fitness. However, the impact of Wolbachia on other microbial associates within the insect microbiome, which are crucial for host fitness, remains less explored. The diamondback moth (Plutella xylostella), a major pest of cruciferous vegetables worldwide, harbors the dominant Wolbachia strain plutWB1, known to distort its sex ratio. This study investigated the bacterial community diversity and dynamics across different developmental life stages and Wolbachia infection states in P. xylostella using high-throughput 16S rDNA amplicon sequencing. Proteobacteria and Firmicutes dominated the P. xylostella microbiome regardless of life stage or Wolbachia infection. However, the relative abundance of dominant genera, including an unclassified genus of Enterobacteriaceae, Wolbachia, Carnobacterium, and Delftia tsuruhatensis, displayed significant stage-specific variations. While significant differences in bacterial diversity and composition were observed across life stages, Wolbachia infection had no substantial impact on overall diversity. Nonetheless, relative abundances of specific genera differed between infection states. Notably, Wolbachia exhibited a stable, high relative abundance across all stages and negatively correlated with an unclassified genus of Enterobacteriaceae, Delftia tsuruhatensis, and Carnobacterium. Our findings provide a foundational understanding of the complex interplay between the host, Wolbachia, and the associated microbiome in P. xylostella, paving the way for a deeper understanding of their complex interactions and potential implications for pest control strategies. Full article

In this study, we synthesized and characterized pH-responsive Chitosan–AgCl-doped ZnO hybrid hydrogels and evaluated their potential for loading aquaculture bioactive compounds, and assessed their antimicrobial properties against a threatening pathogen associated with disease across a broad spectrum of warm water fish and invertebrates. Hydrogel characterization consisted of assessing morphology via SEM, composition via EDS, hydrogels’ network components interactions via FT-IR and pH response through swelling behavior determinations. The swelling characterization of the synthesized hydrogels demonstrated a pH-responsive behavior, showing that low pH values caused the hydrogel polymeric network to expand and capture more of the aqueous solution. These characteristics make the synthesized hydrogels suitable for the encapsulation and controlled release of drugs and bioactive compounds in aquaculture. Chitosan_ZnO hybrid hydrogels showed great antimicrobial activity against Vibrio harveyi, even better than that of loaded PB hydrogels. Here, we provide evidence for the potential capacity of Chitosan_ZnO hybrid hydrogels for the preventive and curative treatment of diseases that impact aquaculture animal health and prevent drug resistance by bacteria. Full article

Antibiotics (ABs) have made it possible to treat bacterial infections, which were in the past untreatable and consequently fatal. Regrettably, their use and abuse among humans and livestock led to antibiotic resistance, which has made them ineffective in many cases. The spread of antibiotic resistance genes (ARGs) and bacteria is not limited to nosocomial environments, but also involves water and soil ecosystems. The environmental presence of ABs and ARGs is a hot topic, and their direct and indirect effects, are still not well known or clarified. A particular concern is the presence of antibiotics in agroecosystems due to the application of agro-zootechnical waste (e.g., manure and biosolids), which can introduce antibiotic residues and ARGs to soils. This review provides an insight of recent findings of AB direct and indirect effects on terrestrial organisms, focusing on plant and invertebrates. Possible changing in viability and organism growth, AB bioaccumulation, and shifts in associated microbiome composition are reported. Oxidative stress responses of plants (such as reactive oxygen species production) to antibiotics are also described. Full article

In this study, we sought to investigate the impact of urbanization, the presence of concrete river bottoms, and nutrient pollution on microbial communities along the L.A. River. Six molecular markers were evaluated for the identification of bacteria, plants, fungi, fish, and invertebrates in 90 samples. PCA (principal components analysis) was used along with PAM (partitioning around medoids) clustering to reveal community structure, and an NB (negative binomial) model in DESeq2 was used for differential abundance analysis. PCA and factor analysis exposed the main axes of variation but were sensitive to outliers. The differential abundance of Proteobacteria was associated with soft-bottom sites, and there was an apparent balance in the abundance of bacteria responsible for nitrogen cycling. Nitrogen cycling was explained via ammonia-oxidizing archaea; the complete ammonia oxidizers, Nitrospira sp.; nitrate-reducing bacteria, Marmoricola sp.; and nitrogen-fixing bacteria Devosia sp., which were differentially abundant at soft-bottom sites (p adj < 0.002). In contrast, the differential abundance of several cyanobacteria and other anoxygenic phototrophs was associated with the impervious sites, which suggested the accumulation of excess nitrogen. The soft-bottom sites tended to be represented by a differential abundance of aerobes, whereas the concrete-associated species tended to be alkaliphilic, saliniphilic, calciphilic, sulfate dependent, and anaerobic. In the Glendale Narrows, downstream from multiple water reclamation plants, there was a differential abundance of cyanobacteria and algae; however, indicator species for low nutrient environments and ammonia-abundance were also present. There was a differential abundance of ascomycetes associated with Arroyo Seco and a differential abundance of Scenedesmaceae green algae and cyanobacteria in Maywood, as seen in the analysis that compared suburban with urban river communities. The proportion of Ascomycota to Basidiomycota within the L.A. River differed from the expected proportion based on published worldwide freshwater and river 18S data; the shift in community structure was most likely associated with the extremes of urbanization. This study indicates that extreme urbanization can result in the overrepresentation of cyanobacterial species that could cause reductions in water quality and safety. Full article

The successions of benthic communities over time are strongly influenced by the first colonizers, because surface associations are facilitated by modifications to the adhesive properties promoted by primary colonizers, such as bacteria, protozoans, diatoms, algal propagules, spores, and invertebrate larvae. Bacteria are often the first colonizers on marine submerged surfaces, both organic (e.g., algae, seagrasses and invertebrates) and inorganic. However, they are promptly followed by diatoms and other microorganisms. Consequently, diatoms may represent key elements in the determination of the colonization patterns, although the development of epiphytic communities is a dynamic process influenced by several factors, including nutrient availability, the ability to synthesize and secrete extracellular material, the competition among species and the influence of grazers on individual colonizers. The process may be drastically impacted by global warming and ocean acidification due to the increasing atmospheric levels of CO₂. The impact of such global stressors on benthic ecosystems, especially on the primary microphytobenthic assemblages, is still poorly investigated, and may have deleterious consequences for the benthic successions. In this review, we analyze the adhesion patterns of marine microorganisms according to their surface features and the effects of global changes on critical pioneer colonizers, such as the benthic diatoms. The results are remarkable, as they highlight emergent concerns in ecosystem conservation and the prediction of benthic communities. Full article

C-type lectin X (CTL-X) plays critical roles in immune defense, cell adhesion, and developmental regulation. Here, a transmembrane CTL-X of Tribolium castaneum, TcCTL15, with multiple domains was characterized. It was highly expressed in the early and late pupae and early adults and was distributed in all examined tissues. In addition, its expression levels were significantly induced after being challenged with pathogen-associated molecular patterns (PAMPs) and bacteria. In vitro, the recombinant TcCTL15 could recognize bacteria through binding PAMPs and exhibit agglutinating activity against a narrow range of bacteria in the presence of Ca²⁺. RNAi-mediated TcCTL15-knockdown-larvae infected with Escherichia coli and Staphylococcus aureus showed less survival, had activated immune signaling pathways, and induced the expression of antimicrobial peptide genes. Moreover, silencing TcCTL15 caused eclosion defects by impairing ecdysone and crustacean cardioactive peptide receptors (CCAPRs). Suppression of TcCTL15 in female adults led to defects in ovary development and fecundity, accompanied by concomitant reductions in the mRNA levels of vitellogenin (TcVg) and farnesol dehydrogenase (TcFDH). These findings imply that TcCTL15 has extensive functions in developmental regulation and antibacterial immunity. Uncovering the function of TcCTL15 will enrich the understanding of CTL-X in invertebrates. Its multiple biological functions endow the potential to be an attractive target for pest control. Full article

The supplementation of pig diets with exogenous enzymes is widely used with the expectation that it will improve the efficiency of nutrient utilization, thereby, improving growth performance. This study aims to evaluate the effects of a 0.1% (v/v) multi-enzyme (a mixture of arazyme (2,500,000 Unit/kg), xylanase (200,000 Unit/kg) and mannanase (200,000 Unit/kg)) supplementation derived from invertebrate symbiotic bacteria on pig performance. Here, 256 growing pigs were assigned to control and treatment groups, respectively. The treatment group exhibited a significantly reduced average slaughter age; the final body weight and average daily gain increased compared with that of the control group. In the treatment group, the longissimus muscle showed a remarkable decrease in cooking loss, shear force, and color values with increased essential and non-essential amino acid concentrations. Furthermore, the concentrations of mono- and polyunsaturated fatty acids in the treatment group increased. Feed additive supplementation increased the family of Ruminococcaceae and genera Lactobacillus, Limosilactobacillus, Turicibacter, and Oscillibacter, which play a positive role in the host physiology and health. Predicted metabolic pathway analysis confirmed that operational taxonomic units and predicted amino acid biosynthesis pathways were strongly associated. The results suggest that applying exogenous enzymes derived from invertebrate symbiotic bacteria enhances animal performance. Full article

S-layers are involved in the adaptation of bacteria to the outside environment and in pathogenesis, often representing special virulence factors. Vegetative cells of the entomopathogenic bacterium Brevibacillus laterosporus are characterized by an overproduction of extracellular surface layers that are released in the medium during growth. The purpose of this study was to characterize cell wall proteins of this bacterium and to investigate their involvement in pathogenesis. Electron microscopy observations documented the presence of multiple S-layers, including an outermost (OW) and a middle (MW) layer, in addition to the peptidoglycan layer covering the plasma membrane. After identifying these proteins (OWP and MWP) by mass spectrometry analyses, and determining their gene sequences, the cell wall multilayer-released fraction was successfully isolated and used in insect bioassays alone and in combination with bacterial spores. This study confirmed a central role of spores in bacterial pathogenicity to insects but also detected a significant virulence associated with fractions containing released cell wall multilayer proteins. Taken together, S-layer proteins appear to be part of the toxins and virulence factors complex of this microbial control agent of invertebrate pests. Full article

Short linear motifs (SLiMs) are evolutionarily conserved functional modules of proteins composed of 3 to 10 residues and involved in multiple cellular functions. Here, we performed a search for SLiMs that exert sequence similarity to two segments of alpha-fetoprotein (AFP), a major mammalian embryonic and cancer-associated protein. Biological activities of the peptides, LDSYQCT (AFP_14–20) and EMTPVNPGV (GIP-9), have been previously confirmed under in vitro and in vivo conditions. In our study, we retrieved a vast array of proteins that contain SLiMs of interest from both prokaryotic and eukaryotic species, including viruses, bacteria, archaea, invertebrates, and vertebrates. Comprehensive Gene Ontology enrichment analysis showed that proteins from multiple functional classes, including enzymes, transcription factors, as well as those involved in signaling, cell cycle, and quality control, and ribosomal proteins were implicated in cellular adaptation to environmental stress conditions. These include response to oxidative and metabolic stress, hypoxia, DNA and RNA damage, protein degradation, as well as antimicrobial, antiviral, and immune response. Thus, our data enabled insights into the common functions of SLiMs evolutionary conserved across all taxonomic categories. These SLiMs can serve as important players in cellular adaptation to stress, which is crucial for cell functioning. Full article

Streptomyces are of great interest in the pharmaceutical industry as they produce a plethora of secondary metabolites that act as antibacterial and antifungal agents. They may thrive on their own in the soil, or associate with other organisms, such as plants or invertebrates. Some soil-derived strains exhibit hemolytic properties when cultivated on blood agar, raising the question of whether hemolysis could be a virulence factor of the bacteria. In this work we examined hemolytic compound production in 23 β-hemolytic Streptomyces isolates; of these 12 were soil-derived, 10 were arthropod-associated, and 1 was plant-associated. An additional human-associated S. sp. TR1341 served as a control. Mass spectrometry analysis suggested synthesis of polyene molecules responsible for the hemolysis: candicidins, filipins, strevertene A, tetrafungin, and tetrin A, as well as four novel polyene compounds (denoted here as polyene A, B, C, and D) in individual liquid cultures or paired co-cultures. The non-polyene antifungal compounds actiphenol and surugamide A were also identified. The findings indicate that the ability of Streptomyces to produce cytolytic compounds (here manifested by hemolysis on blood agar) is an intrinsic feature of the bacteria in the soil environment and could even serve as a virulence factor when colonizing available host organisms. Additionally, a literature review of polyenes and non-polyene hemolytic metabolites produced by Streptomyces is presented. Full article