Gram-positive Genera Research Articles

Isolation and characterization of algicidal bacteria from freshwater aquatic environments in China.

Algicidal bacteria can inhibit the growth of algae or lyse algal cells, thus playing roles in shaping aquatic microbial communities and maintaining the functions of aquatic ecosystems. Nevertheless, our understanding of their diversities and distributions remains limited. In this study, we collected water samples from 17 freshwater sites in 14 cities in China and screened a total of 77 algicidal bacterial strains using several prokaryotic cyanobacteria and eukaryotic algae as target strains. According to their target-specificities, these strains were classified into three subgroups, cyanobacterial algicidal bacteria, algal algicidal bacteria, and broad-target algicidal bacteria, each displaying distinctive compositions and geographical distribution patterns. They are assigned to Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes bacterial phyla, of which Pseudomonas and Bacillus are the most abundant gram-negative and gram-positive genus, respectively. A number of bacterial strains, such as Inhella inkyongensis and Massilia eburnean, are suggested as new algicidal bacteria. The diverse taxonomies, algal-inhibiting abilities and distributions of these isolates have suggested that there are rich algicidal bacterial resources in these aquatic environments. Our results provide new microbial resources for algal-bacterial interaction studies, and shed new insights into how algicidal bacteria can be used in the control of harmful algal blooms, as well as in algal biotechnology.

How anaerobic sludge microbiome respond to different concentrations of nitrite, nitrate, and ammonium ions: a comparative analysis.

High concentrations of ammonium, nitrite, and nitrate always induce inhibition in anaerobic wastewater treatment. Due to the complexity and vulnerability of the microbial community (especially methanogens) in anaerobic sludge, little is understood about its underlying microbial mechanism under such inhibition. In this study, the shifts of microbial communities in anaerobic sludge under increasing levels of nitrite, nitrate, and ammonium ions were compared. Results show that although half maximal inhibitory concentrations (methanogenesis) were different for nitrite, nitrate, and ammonium ions with EC50 values of 12, 30, and 3000mg N/L, respectively, bacteria genera Kosmotoga and Brooklawnia dominated in all of the three high-stress inhibitory systems. Network analysis and redundancy analysis (RDA) of the microbial community showed the treatments with nitrate and nitrite ions decreased the modularity of anaerobic microorganisms. RDA showed that specific methanogenic activity was positively related to coenzyme F420 under nitrite inhibition (rp = 0.833, p < 0.05) and closely correlated with viability under nitrate inhibition. Gram-positive and nonmotile Brooklawnia genus showed a negative correlation with physiological characteristics in the ammonia treatments, suggesting its high resistance to ammonia.

A Study of Urinary Tract Infections Prevalence, Antibiotics Resistance, and Biofilm Formation Capability of the Bacterial Causal Agents

The aim of this study was to evaluate the incidence of UTI in Salahadin governorate/Iraq, identify the causative agents, their antibiotic sensitivity and their ability to form biofilms; such studies are mandatory to determine the empirical therapy of such cases. A total of 650 urine samples were collected. Two hundred and fifty samples were cultured, as suspected of having UTI, and 193 samples (77.2 %) showed growth (Positive culture), while 57 samples (22.8 %) were negative cultures. Gram-positive bacteria were the predominant cause of UTI (66.7%), while Gram-negative species were found in 33.3%. Staphyloccus spp. were the predominant Gram-positive genus to isolate from UTI patients, while E. coli was the predominant among Gram-negative bacteria. The isolates were tested for antibiotic susceptibility and biofilm formation. The most effective tested antibiotic on the Gram-positive isolates was Nitrofurantoin followed by Chloramphenicol (resistance percentage 19 and 20% respectively), and the least effective one was Azithromycin (64% resistance). While the most effective tested antibiotic on the Gram-egative isolates was Amikacin (only 8% resistance), and the least effective one was erythromycin (98% resistance). Biofilm detection by Congo red agar (CRA) method and microtiter plate (MTP) assay were done; the results showed that by CRA method 81.3% of isolates were biofilm formers. While 96.7% of isolates were detected as biofilm formers by microtiter plat assay. Generally, biofilm formation was more predominant among Gram-positive isolates than Gram-negative ones

The Clostridium-infecting filamentous phage CAK1 genome analysis allows to define a new potential clade of Tubulavirales.

What we know about Tubulavirales, i.e. filamentous phages, essentially comes from Gram-negative-infecting Inoviridae. However, metagenomics recently suggests filamentous phages are much more widespread and diverse. Here, we report the complete sequence and functional annotation of CAK1, a 6.6kb filamentous phage that was shown to chronically infect Clostridium beijerinckii 30 years ago and only represents the second filamentous phage cultivated on a Gram-positive bacterium. CAK1 has a typical filamentous phage modular genome with no homologs in databases and we were interested to compare it with a pig gut filamentous phage metagenomics dataset that we previously assembled and for which many filamentous phages were predicted to infect Clostridium species by bioinformatics means. CAK1 is distantly related to nine of these sequences, two of which having been predicted as Clostridium-associated. In itself, this small cluster of CAK1-connected sequences sheds light on the diversity of filamentous phages that putatively infect Clostridium species, and probably many other Gram-positive genera.

Microbial metabolites indole derivatives sensitize mice to D-GalN/LPS induced-acute liver failure via the Tlr2/NF-κB pathway.

Acute liver failure (ALF) is a clinical condition with many causes, fast progression, and a poor prognosis. Previous research has indicated that microbial factors have a role in ALF, but a clear picture has yet to emerge. To investigate the specific involvement of microbial metabolites in ALF development, we pretreated D-GalN/LPS-induced ALF mice with indole derivatives, an influential class of gut microbial metabolites. Contrary to their typical role as anti-inflammatory agents in the host, indole-3-acetic acid (IAA), indole-3-lactic acid (ILA), and indolepropionic acid (IPA) gavage sensitize mice to D-GalN/LPS-induced-ALF with a rapid rise in serum transaminases and histologic lesion. For a clearer picture, we performed comprehensive analysis for the IAA therapy. IAA markedly amplified inflammatory response and cellular damage. The transcriptome analysis indicated the participation of the TNF-α/NF-κB signaling pathway. The structure of gut microbiota in ileum and the expression of Toll-like receptor 2 (Tlr2) in the liver were also significantly changed. In conclusion, IAA pretreatment can exacerbate D-GalN/LPS-induced ALF via probable Tlr2/NF-κB pathway involvement and ileac dysbiosis characterized by enriched gram-positive genus with potential pathogenesis. Microbial metabolites IAA may aggravate individual susceptibility to D-GalN/LPS-induced ALF. Further investigation of the underlying mechanism is needed, and intervention with indole derivatives and related commensal species should be undertaken with caution.

Elevation of Clavibacter michiganensis subsp. californiensis to species level as Clavibacter californiensis sp. nov., merging and re-classification of Clavibacter michiganensis subsp. chilensis and Clavibacter michiganensis subsp. phaseoli as Clavibacter phaseoli sp. nov. based on complete genome in silico analyses.

The Gram-positive genus Clavibacter is currently divided into seven species (Clavibacter michiganensis, Clavibacter nebraskensis, Clavibacter capsici, Clavibacter sepedonicus, Clavibacter tessellarius, Clavibacter insidiosus and Clavibacter zhangzhiyongii) and three subspecies (C. michiganensis subsp. californiensis, C. michiganensis subsp. chilensis and C. michiganensis subsp. phaseoli). Recent studies have indicated that the taxonomic rank of the subspecies must be re-evaluated. In this research, we assessed the taxonomic position of the three C. michiganensis subspecies and clarified the taxonomic nomenclature of other 75 Clavibacter strains. The complete genomes of the type strains of the three Clavibacter subspecies, the type strain of C. tessellarius and C. nebraskensis A6096 were sequenced using PacBio RSII technology. Application of whole-genome-based computational approaches such as average nucleotide identity (ANI), digital DNA-DNA hybridization, multi-locus sequence analysis of seven housekeeping genes (acnA, atpD, bipA, icdA, mtlD, recA and rpoB), a phylogenomic tree reconstructed from 1 028 core genes, and ANI-based phylogeny provided sufficient justification for raising C. michiganensis subsp. californiensis to the species level. These results led us to propose the establishment of Clavibacter californiensis sp. nov. as a species with its type strain C55T (=CFBP 8216T=ATCC BAA-2691T). Moreover, the orthologous and in silico dot plot analyses, along with the above described bioinformatic strategies, revealed a high degree of similarity between C. michiganensis subsp. chilensis and C. michiganensis subsp. phaseoli. Based on these analyses, we propose that both subspecies be combined into a single taxon and elevated to the species level as Clavibacter phaseoli sp. nov., with LPPA 982T (= CECT 8144T= LMG 27667T) as the type strain.

Abundance, isolation, and characterization of halotolerant microbes from common oligosaline soils

Halotolerant microbes that grow at high NaCl concentrations were studied in common soils with low salinity. The abundance of microbes in common oligosaline (<1.0% salinity) soils was measured by most probable number analyses, where statistically valid replicates of serial dilutions were assessed for growth in liquid Salt Plains medium with 0.1, 10, or 20% (w/v) NaCl. Common Kansas soils were collected from oligosaline agricultural fields (corn, cotton, sorghum, and soybean), pond margin, prairie grassland, and woodland. The abundance of microbes able to grow at 10% NaCl was 0.0025–0.32% of the total counts at 0.1% NaCl. Only marginal growth was observed at 20% NaCl, about 100-fold lower than at 10% NaCl. Bacterial isolates were collected from 20% NaCl enrichments of oligosaline turf soil by repetitive streak-plating. The bacteria were identified by 16S rRNA gene sequencing and characterized. The isolates clustered with low G+C Gram-positive genera (Bacillus, Halobacillus, Staphylococcus, and Virgibacillus). Broad halotolerances (0.1–20% NaCl) were observed for most isolates, but all grew at low salt. Soils were boiled to kill vegetative cells and compared by most probable number analyses with unboiled specimens. The abundance of microbes able to grow at 10% NaCl showed a 3-log decrease with boiling, while microbes able to grow at 0.1% NaCl showed a 5-log decrease in abundance with boiling. It appears that halotolerant microbes in oligosaline soils are cultivable vegetative cells, not perennating structures such as spores. Discrete salt phases are not obvious in oligosaline soils, but could provide a selective advantage to autochthonous halotolerant microbes. Allochthonous microbes associated with salt evaporite particles may be transported by winds, thereby dispersing deliquescent hypersaline microhabitats.

Microbial Contamination of Photographic and Cinematographic Materials in Archival Funds in the Czech Republic.

In this study we investigated the microbial contamination of 126 samples of photographic and cinematographic materials from 10 archival funds in the Czech Republic. Microorganisms were isolated from the light-sensitive layer by swabbing it with a polyurethane sponge. Microbial isolates were identified by MALDI-TOF MS (bacteria) or by phenotype testing and microscopy (fungi). Bacterial contamination was more abundant and more diverse than fungal contamination, and both were significantly associated with archives. The most frequently isolated fungal genera were Cladosporium, Eurotium, Penicillium, Aspergillus and Alternaria. The most frequently isolated bacteria were Gram-positive genera such as Staphylococcus, Micrococcus, Kocuria, Streptococcus and Bacillus. This bacterial and fungal diversity suggests that air is the main vehicle of contamination. We also analysed the impact of the type of material used for the carrier (paper, baryta paper, cellulose acetate and nitrate or glass) or the light-sensitive layer (albumen, gelatine, collodion and other) on the level and diversity of microbial contamination. Carriers such as polyester and cellulose nitrate may have a negative impact on bacterial contamination, while paper and baryta paper may have a partially positive impact on both fungal and bacterial contamination.

Unmarked Gene Editing in Clavibacter michiganensis Using CRISPR/Cas9 and 5-Fluorocytosine Counterselection.

Plant-pathogenic bacteria in the genus Clavibacter are important quarantine species that cause considerable economic loss worldwide. The development of effective gene editing techniques and additional selectable markers is essential to expedite gene functional analysis in this important Gram-positive genus. The current study details a highly efficient unmarked CRISPR/Cas9-mediated gene editing system in Clavibacter michiganensis, which couples the expression of cas9 and single-guide RNA with homology-directed repair templates and the negative selectable marker codA::upp within a single plasmid. Initial experiments indicated that CRISPR/Cas9-mediated transformation could be utilized for both site-directed mutagenesis, in which an A to G point mutation was introduced at the 128th nucleotide of the C. michiganensis rpsL gene to generate a streptomycin-resistant mutant, and complete gene knockout, in which the deletion of the C. michiganensis celA or katA genes resulted in transformants that lacked cellulase and catalase activity, respectively. In subsequent experiments, the introduction of the codA::upp cassette into the transformation vector facilitated the counterselection of unmarked transformants by incubation in the absence of the selective antibiotic, followed by plating on M9 agar containing 5-fluorocytosine at 100 μg/ml, in which an unmarked katA mutant lacking the transformation vector was recovered. Compared with conventional homologous recombination, the unmarked CRISPR/Cas9-mediated system was more useful and convenient because it allowed the template plasmid to be reused repeatedly to facilitate the editing of multiple genes, which constitutes a major advancement that could revolutionize research into C. michiganensis and other Clavibacter spp.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Extensive Horizontal Gene Transfer within and between Species of Coagulase-Negative Staphylococcus.

Members of the gram-positive bacterial genus Staphylococcus have historically been classified into coagulase-positive Staphylococcus (CoPS) and coagulase-negative Staphylococcus (CoNS) based on the diagnostic presentation of the coagulase protein. Previous studies have noted the importance of horizontal gene transfer (HGT) and recombination in the more well-known CoPS species Staphylococcus aureus, yet little is known of the contributions of these processes in CoNS evolution. In this study, we aimed to elucidate the phylogenetic relationships, genomic characteristics, and frequencies of HGT in CoNS, which are now being recognized as major opportunistic pathogens of humans. We compiled a data set of 1,876 publicly available named CoNS genomes. These can be delineated into 55 species based on allele differences in 462 core genes and variation in accessory gene content. CoNS species are a reservoir of transferrable genes associated with resistance to diverse classes of antimicrobials. We also identified nine types of the mobile genetic element SCCmec, which carries the methicillin resistance determinant mecA. Other frequently transferred genes included those associated with resistance to heavy metals, surface-associated proteins related to virulence and biofilm formation, type VII secretion system, iron capture, recombination, and metabolic enzymes. The highest frequencies of receipt and donation of recombined DNA fragments were observed in Staphylococcus capitis, Staphylococcus caprae, Staphylococcus hominis, Staphylococcus haemolyticus, and members of the Saprophyticus species group. The variable rates of recombination and biases in transfer partners imply that certain CoNS species function as hubs of gene flow and major reservoir of genetic diversity for the entire genus.

Validation of neonatal and paediatric antimicrobial stewardship treatment algorithms in rapid diagnostic-detected bacteraemia.

Blood culture rapid diagnostic testing (RDT) aids in early organism identification and resistance gene detection. This information allows quicker transition to tailored antimicrobial therapy, improved patient outcomes and prevention of antimicrobial resistance. An antimicrobial treatment algorithm based on RDT results and local antibiograms can serve as a valuable clinical decision-support tool. This study assessed the proportion of appropriate antibiotic therapy recommendations using a novel paediatric RDT-guided treatment algorithm compared with standard care (SC) in paediatric bacteraemia. This was a retrospective, observational study of admitted paediatric patients who received antibiotics for RDT-confirmed bacteraemia. Appropriateness of SC was compared with algorithm-recommended treatment. Antimicrobial appropriateness was defined as in vitro susceptibility to the organism identified through traditional microbiology. Clinical appropriateness took into consideration the ability to tailor therapy within 12 h of RDT results. Appropriateness was evaluated by two blinded, independent reviewers. Eighty-six blood cultures were included with 15 unique Gram-positive and Gram-negative species or genus identified. Comparative antimicrobial appropriateness of SC and algorithm-recommended treatment was 94.2% (81/86) and 100% (86/86), respectively (P = 0.06). Clinical assessment determined 39.5% (34/86) of SC patients were on appropriate therapy within 12 h of RDT result. Algorithm-recommended therapy was clinically appropriate in 97.7% (84/86) of patients (P < 0.001). There was a median time savings of 42.7 h (IQR 40.6, 49.4) for the patients able to be de-escalated as compared with waiting on final sensitivities. Algorithm-guided treatment may allow most patients to be de-escalated to organism-tailored therapy earlier in their therapeutic course.

S-layers: The Proteinaceous Multifunctional Armors of Gram-Positive Pathogens.

S-layers are self-assembled crystalline 2D lattices enclosing the cell envelopes of several bacteria and archaea. Despite their abundance, the landscape of S-layer structure and function remains a land of wonder. By virtue of their location, bacterial S-layers have been hypothesized to add structural stability to the cell envelope. In addition, S-layers are implicated in mediating cell-environment and cell-host interactions playing a key role in adhesion, cell growth, and division. Significant strides in the understanding of these bacterial cell envelope components were made possible by recent studies that have provided structural and functional insights on the critical S-layer and S-layer-associated proteins (SLPs and SLAPs), highlighting their roles in pathogenicity and their potential as therapeutic or vaccine targets. In this mini-review, we revisit the sequence-structure-function relationships of S-layers, SLPs, and SLAPs in Gram-positive pathogens, focusing on the best-studied classes, Bacilli (Bacillus anthracis) and Clostridia (Clostridioides difficile). We delineate the domains and their architectures in archetypal S-layer proteins across Gram-positive genera and reconcile them with experimental findings. Similarly, we highlight a few key “flavors” of SLPs displayed by Gram-positive pathogens to assemble and support the bacterial S-layers. Together, these findings indicate that S-layers are excellent candidates for translational research (developing diagnostics, antibacterial therapeutics, and vaccines) since they display the three crucial characteristics: accessible location at the cell surface, abundance, and unique lineage-specific signatures.

Interaction study of Pasteurella multocida with culturable aerobic bacteria isolated from porcine respiratory tracts using coculture in conditioned media

BackgroundThe porcine respiratory tract harbours multiple microorganisms, and the interactions between these organisms could be associated with animal health status. Pasteurella multocida is a culturable facultative anaerobic bacterium isolated from healthy and diseased porcine respiratory tracts. The interaction between P. multocida and other aerobic commensal bacteria in the porcine respiratory tract is not well understood. This study aimed to determine the interactions between porcine P. multocida capsular serotype A and D strains and other culturable aerobic bacteria isolated from porcine respiratory tracts using a coculture assay in conditioned media followed by calculation of the growth rates and interaction parameters.ResultsOne hundred and sixteen bacterial samples were isolated from five porcine respiratory tracts, and 93 isolates were identified and phylogenetically classified into fourteen genera based on 16S rRNA sequences. Thirteen isolates from Gram-negative bacterial genera and two isolates from the Gram-positive bacterial genus were selected for coculture with P. multocida. From 17 × 17 (289) interaction pairs, the majority of 220 pairs had negative interactions indicating competition for nutrients and space, while 17 pairs were identified as mild cooperative or positive interactions indicating their coexistence. All conditioned media, except those of Acinetobacter, could inhibit P. multocida growth. Conversely, the conditioned media of P. multocida also inhibited the growth of nine isolates plus themselves.ConclusionNegative interaction was the major interactions among the coculture of these 15 representative isolates and the coculture with P. multocida. The conditioned media in this study might be further analysed to identify critical molecules and examined by the in vivo experiments. The study proposed the possibility of using these molecules in conditioned media to control P. multocida growth.

Biosorption of heavy metals by dry biomass of metal tolerant bacterial biosorbents: an efficient metal clean-up strategy.

Heavy metals discharge at an unrestrained rate from various industries into the environment pose serious human health problems. Considering this, the present study aimed at exploring the metal biosorbing potentials of bacterial strains recovered from polluted soils. The bacterial strains (CPSB1, BM2 and CAZ3) belonging to genera Pseudomonas, Bacillus and Azotobacter expressing multi-metal tolerance ability were identified to species level as P. aeruginosa, B. subtilis and A. chroococcum, respectively, by 16S rRNA partial gene sequence analysis. The biosorption of cadmium, chromium, copper, nickel, lead and zinc by three dead bacterial genera were studied as a function of metal concentration, variable pH of the medium and reaction (contact) time. The three bacterial strains exhibited a tremendous metal removal ability which continued even at the highest tested concentration of some metals. Later, a decline in the percentage of biosorbed metals was recorded as the metal concentration was increased with the simultaneous generation of a driving force to overcome mass transfer resistance for movement of metal ions between the solution and the surface of adsorbent. Among test bacteria, B. subtilis biosorbed a maximum of 96% chromium at 25μgmL-1 while the maximum percentage (91%) of biosorbed metals recorded at 400μg CdmL-1 was observed for P. aeruginosa. The sorption of metal ions by dead biomass of three bacterial genera at optimum conditions followed the order-(i) B. subtilis BM2: Pb > Cu > Ni > Cd > Cr, (ii) A. chroococcum CAZ3: Cr > Cd > Cu > Ni > Pb and (iii) P. aeruginosa CPSB1: Cd > Cr > Ni > Cu > Pb > Zn. It was found that the optimum pH for metal adsorption ranged between pH8 and 9 which, however, declined substantially at pH5.0 for all three bacterial strains. In general, the biosorption of Cd, Cr, Cu, Ni and Pb by B. subtilis and A. chroococcum and such metals along with Zn by P. aeruginosa occurred maximally up to 60min of bacterial growth. The adsorption data with regard to five metals provide an outstanding fit to the Langmuir and Freundlich isotherms. The biosorptive ability of three bacterial genera correlated strongly (r2 > 0.9) with each metal. The bacteria belonging to two Gram-negative genera Pseudomonas (P. aeruginosa) and Azotobacter (A. chroococcum) and one Gram-positive genus Bacillus (B. subtilis) demonstrated exceptional metal removal efficiency and, hence, provides a comprehensive understanding of metal-bacteria sorption process which in effect paves the way for detoxifying/removing metals from contaminated environment.

Quantification of Bacterial Metabolic Activities in the Gut by d-Amino Acid-Based In Vivo Labeling.

Herein, we propose a metabolic d-amino acid-based labeling and in situ hybridization-facilitated (MeDabLISH) strategy for the quantitative analysis of the indigenous metabolic status of gut bacteria. The fluorescent d-amino acid (FDAA)-based labeling intensities of bacteria were found to highly correlate with their temporal and steady-state metabolic status. Then, after taxonomic identification of bacterial genera in the in vivo FDAA-labeled mouse gut microbiota, by corresponding fluorescence in situ hybridization (FISH) probes, the metabolic activities of different gut bacterial genera are quantified by flow cytometry, using FISH signals to differentiate genera and FDAA signals to indicate their basal metabolic levels. It was found that Gram-negative genera in the mouse microbiota have stronger metabolic activities during the daytime, and Gram-positive genera have higher activities at the night. Our strategy will be instrumental in deepening our understanding of the highly complex microbiota.

Evaluation of cultivable aerobic bacterial flora from Russell's viper (Daboia russelii) oral cavity

Snake mouths contain a wide range of bacteria. Identifying these bacteria in snakes is very important to obtain an understanding of the etiological agents of secondary infections that may result from accidents during handling and/or snake bites. The present study aims to determine the pattern of oral bacterial flora of nine healthy Russell's vipers (Daboia russelii), and their susceptibility to common antibiotics. A total of 94 isolates were obtained in pure form, which demonstrated noticeable colony characteristics and which were further studied with several biochemical tests. The strains that showed distinctive colonies, morphology and biochemical parameters were additionally subjected to phylogenetic characterization using 16S rRNA gene sequences. Furthermore, all these isolates were studied for antibiotic susceptibility. The oral cavity of the Russell's viper harbors a wide range of pathogenic bacteria, including Gram-negative genera: Proteus sp., Pseudomonas sp., Salmonella sp., Providencia sp., Alcaligenes sp., Morganella sp., as well as E. coli, and Gram-positive genera: Bacillus and Enterococcus sp., Staphylococcus sp. and Lysinobacillus sp. Most of the isolates were resistant to antibiotics viz. penicillin, Amoxyclav, oxacillin, methicillin and streptomycin while sensitive towards imipenem, amikacin, norfloxacin, gatifloxacin, ciprofloxacin, gentamicin, tetracycline, chloramphenicol and azithromycin. The present study documents diverse bacteria predominant in the oral cavity of Daboia russelii and studied their antibiotic susceptibilities.

Biological Control of Fusarium Crown and Root Rot of Wheat by Streptomyces Isolates – It’s Complicated

The predominant causal agents of Fusarium crown and root rot (FCR) of wheat, along with Fusarium pseudograminearum, are F. graminearum and F. culmorum. Members of the Gram-positive bacterial genus Streptomyces have been shown to inhibit isolates of the genus Fusarium, and Fusarium spp. isolates are also able to inhibit Streptomyces isolates in vitro. However, little is known about these complex antagonistic interactions and the potential for inhibitory Streptomyces to reduce FCR of wheat. The aim of this study was to analyze whether inhibitory Streptomyces isolates affect FCR of wheat and reduce root and stem base colonization by Fusarium culmorum. We enriched sterilized potting soil with spore suspensions of two Streptomyces isolates, inoculated the soil with F. culmorum-colonized wheat straw, and planted pre-germinated wheat seedlings. At 4 weeks, F. culmorum-inoculated plants had significant FCR symptoms on roots and showed reduced fresh weight of roots and above-ground plant biomass compared with the non-inoculated controls. Enrichment of soil with an inhibitory Streptomyces isolate reduced F. culmorum DNA in roots and stem bases by 75% compared with inoculation with F. culmorum alone. Interestingly, co-inoculation of F. culmorum with a non-inhibitory Streptomyces isolate led to the highest levels F. culmorum DNA in stem base tissue and greatest Streptomyces densities (CFU per g of soil) in the rhizosphere. In vitro assays revealed that F. culmorum showed a strong inhibitory activity against the pathogen-inhibitory Streptomyces isolate but not against the non-inhibitory isolate. In vitro tests with a larger set of 17 Streptomyces and five Fusarium spp. isolates revealed that there was little variation among Fusarium spp. isolates in capacities to inhibit the collection of Streptomyces isolates. In contrast, the sensitivity to inhibition by pathogenic Fusarium spp. isolates varied widely among Streptomyces isolates. The results of this study suggest the potential of Streptomyces isolates for biocontrol of FCR of wheat, while highlighting the specificity of Streptomyces−Fusarium interactions. Broader understanding of the variation in susceptibility within Fusarium spp. populations to Streptomyces inhibition and vice versa are needed to advance the potential for successful biological control.

Wild bees and their nests host Paenibacillus bacteria with functional potential of avail

BackgroundIn previous studies, the gram-positive firmicute genus Paenibacillus was found with significant abundances in nests of wild solitary bees. Paenibacillus larvae is well-known for beekeepers as a severe pathogen causing the fatal honey bee disease American foulbrood, and other members of the genus are either secondary invaders of European foulbrood or considered a threat to honey bees. We thus investigated whether Paenibacillus is a common bacterium associated with various wild bees and hence poses a latent threat to honey bees visiting the same flowers.ResultsWe collected 202 samples from 82 individuals or nests of 13 bee species at the same location and screened each for Paenibacillus using high-throughput sequencing-based 16S metabarcoding. We then isolated the identified strain Paenibacillus MBD-MB06 from a solitary bee nest and sequenced its genome. We did find conserved toxin genes and such encoding for chitin-binding proteins, yet none specifically related to foulbrood virulence or chitinases. Phylogenomic analysis revealed a closer relationship to strains of root-associated Paenibacillus rather than strains causing foulbrood or other accompanying diseases. We found anti-microbial evidence within the genome, confirmed by experimental bioassays with strong growth inhibition of selected fungi as well as gram-positive and gram-negative bacteria.ConclusionsThe isolated wild bee associate Paenibacillus MBD-MB06 is a common, but irregularly occurring part of wild bee microbiomes, present on adult body surfaces and guts and within nests especially in megachilids. It was phylogenetically and functionally distinct from harmful members causing honey bee colony diseases, although it shared few conserved proteins putatively toxic to insects that might indicate ancestral predisposition for the evolution of insect pathogens within the group. By contrast, our strain showed anti-microbial capabilities and the genome further indicates abilities for chitin-binding and biofilm-forming, suggesting it is likely a useful associate to avoid fungal penetration of the bee cuticula and a beneficial inhabitant of nests to repress fungal threats in humid and nutrient-rich environments of wild bee nests.

Działanie olejku lawendowego (Oleum Lavandulae) na bakterie beztlenowe

Introduction. Therapeutical, cosmetical and culinary properties of lavender oil was valued from ancient. Lavandula angustifolia Mill. (Lavandula officinalis Chaix.) belonging to the family Lamiaceae. Lavender produced essential oil. It possess different property: hepatoprotective, antidiabetic, antispasmotic, antiulcers, antidepression, antioxidant, antireumatic, insect repellent and antimicrobial. Aim. The aim of this work was to investigate the susceptibility of anaerobes of oral cavity to lavender oil. Material and methods. The anaerobic bacteria were isolated from various infections of oral cavity. A total 32 strains of bacteria isolated from patients and 5 reference strains were examined. The susceptibility (MIC) anaerobes to lavender oil was determined by means of plate dilution technique in Brucella agar, supplemented with 5% defibrynated sheep blood, menadione and hemin. Stock solution of essential oil was prepared in dimethylsulfoxide (DMSO) and afterwords in distilled water. Concentration of oil used were: 0.12, 0.25, 0.5, 1.0 and 2.0 mg/ml. The inoculum contained 106 CFU per spot was seeded with Steers’ replicator upon the surface of agar with oil and without the oil (strains growth control). Incubation was performed in anaerobic conditions in anaerobic jars, at 37°C for 48 hrs. The MIC was interpreted as the lowest concentration of lavender oils inhibiting the growth of tested anaerobic bacteria. Results. The results indicated, that from all tested anaerobes 10 (31%) was susceptible in ranges &lt; 0.12-0.5 mg/ml. The oil was active towards 53% strains in concentration = 1.0 mg/ml. The MIC for remaining strains was &gt; 2.0 mg/ml. From the Gram-positive cocci the most susceptible were the strains Peptostreptococcus anaerobius. MIC of the strains were &lt; 0.12 mg/ml. The Gram-positive rods were the lowest sensitive. The lavender oil inhibited growth of this bacteria in concentration = 1.0 mg/ml. Conclusions. The more susceptible to lavender oil, from Gram-negative bacteria were the genus Bacteroides vulgatus, Bacteroides uniformis and from Gram-positive cocci genus Peptostreptococcus anaerobius. The Gram-negative anaerobes were less susceptible to tested oil than Gram-positive anaerobic bacteria.

Przeciwbakteryjne działanie olejku rozmarynowego (Oleum Rosmarini) na bakterie beztlenowe

Introduction. Rosmarinus officinalis L. a member of family Lamiaceae is widely found in many countries of North Africa, America and Europa. It grown to 2-3 m high. The plant produced of essential oils. The composition of rosemary oil based on genotype, climate, geography, and method of preparation. The major constituents of the oil are 1-8 cineole, α-pinene, camphene, α-terpineol, borneol, camphor, β-myrcene, geraniol, eugenol, p-cymen, linalool, romarinic acid and caffeic acid. Rosmarinic acid is well adsorbed from gastrointestinal tract and from the skin. The oil is used in medicine as an anti-inflammation, anticancer, analgesic, antidiabetic, antiulcerogenic, hepatoprotective, antirheumatic, antiepileptic, diuretic and anti Alzheimer disease. The extracts and essential oil have antimicrobial activity towards bacteria, fungi, viruses and insects. Aim. The goal of this work was to test the antimicrobial activity of rosmarinic oil on anaerobic bacteria. Material and methods. The bacterial strains were isolated from oral cavity. A total 33 strains of anaerobic bacteria isolated from patients and 6 reference strains were investigated. The susceptibility (MIC) was determined by the two-fold of plate dilution method in Brucella agar supplemented with 5% defibrinated sheep blood, menadione and hemin. The rosmarinic oil (Semifarm) was dissolved at first in DMSO and afterwards in distilled water. Concentrations of oil used were 0.06, 0.12, 0.25, 0.5, 1.0 and 2.0 mg/ml. The inoculum containing 106 CFU/per spot was seeded with Steers replicator upon the surface of agar with oil and without the oil (the strains growth control). Incubation the plates was performed in anaerobic conditions in anaerobic jar, at 37°C for 48 hrs. The MIC was defined as the lowest concentrations of rosmarinic oil that completely inhibited the growth of tested anaerobic bacteria. Results. The results indicated that the tested bacteria were high sensitive to the essential oils. The most susceptible from Gram-negative bacteria were the rods from genus of Porphyromonas asaccharolytica, Prevotella levii and Bacteroides uniformis (MIC ≤ 0.06 mg/ml). The strains from genus Prevotella buccalis and Bacteroides vulgatus were less sensitive (MIC = 0.5 mg/ml). Remainded Gram-negative rods were susceptible to the oil in concentrations in range from 0.5 to 1.0 mg/ml. The rosmarinus oil was more effective against the Gram-positive bacteria. The most susceptible from the cocci were strains from the genus of Peptostreptococcus anaerobius and Parvimonas micros (MIC 0.25-≤ 0.06 mg/ml) and from rods Gram-positive rods genus of Actinomyces viscosus and Bifidobacterium breve (MIC 0.12-≤ 0.06 mg/ml). Conclusions. The results indicated that the rosmarinic oil showed high antibacterial activity against all tested anaerobic bacteria. The more susceptible to oil were the Gram-positive bacterial strains than Gram-negative anaerobic rods.