Water deficits shape the microbiome of Bermudagrass roots to be Actinobacteria rich.

There is increasing evidence that microbes can help ameliorate plant growth under environmental stress. Still, it is largely unknown what microbes and potential functions are involved in sustaining turfgrass, the major component of urban/suburban landscapes, under drought. We examined microbial responses to water deficits in bulk soil, rhizosphere, and root endosphere of bermudagrass by applying evapotranspiration (ET)-based dynamic irrigation twice per week during the growing season to create six treatments (0%, 40%, 60%, 80%, 100%, and 120% ET) and respective drought-stressed soil conditions. Bacterial and fungal communities were analyzed via marker gene amplicon sequencing and thereafter drought-reshaped potential functions of the bacterial community were projected. Slight yet significant microbial responses to irrigation treatments were observed in all three microhabitats. The root endophytic bacterial community was most responsive to water stress. No-irrigation primarily increased the relative abundance of root endophytic Actinobacteria, especially the genus Streptomyces. Irrigation at ≤40% ET increased the relative abundances of PICRUSt2-predicted functional genes encoding 1-aminocyclopropane-1-carboxylic acid deaminase, superoxide dismutase, and chitinase in root endosphere. Our data suggest that the root endophytic Actinobacteria are likely the key players to improve bermudagrass fitness under drought by modulating phytohormone ethylene production, scavenging reactive oxygen species, or ameliorating nutrient acquisition.

Dual-Mechanism Confers Self-Resistance to the Antituberculosis Antibiotic Capreomycin.

Capreomycin (CMN) is an important second-line antituberculosis antibiotic isolated from Saccharothrix mutabilis subspecies capreolus. The gene cluster for CMN biosynthesis has been identified and sequenced, wherein the cph gene was annotated as a phosphotransferase likely engaging in self-resistance. Previous studies reported that Cph inactivates two CMNs, CMN IA and IIA, by phosphorylation. We, herein, report that (1) Escherichia coli harboring the cph gene becomes resistant to both CMN IIA and IIB, (2) phylogenetic analysis regroups Cph to a new clade in the phosphotransferase protein family, (3) Cph shares a three-dimensional structure akin to the aminoglycoside phosphotransferases with a high binding affinity (KD) to both CMN IIA and IIB at micromolar levels, and (4) Cph utilizes either ATP or GTP as a phosphate group donor transferring its γ-phosphate to the hydroxyl group of CMN IIA. Until now, Cph and Vph (viomycin phosphotransferase) are the only two known enzymes inactivating peptide-based antibiotics through phosphorylation. Our biochemical characterization and structural determination conclude that Cph confers the gene-carrying species resistance to CMN by means of either chemical modification or physical sequestration, a naturally manifested belt and braces strategy. These findings add a new chapter into the self-resistance of bioactive natural products, which is often overlooked while designing new bioactive molecules.

Rid7C, a Member of the YjgF/YER057c/UK114 (Rid) Protein Family, Is a Novel Endoribonuclease That Regulates the Expression of a Specialist RNA Polymerase Involved in Differentiation in Nonomuraea gerenzanensis.

The YjgF/YER057c/UK114 (Rid) is a protein family breadth conserved in all domains of life and includes the widely distributed archetypal RidA (YjgF) subfamily and seven other subfamilies (Rid1 to Rid7). Among these subfamilies, RidA is the only family to have been biochemically well characterized and is involved in the deamination of the reactive enamine/imine intermediates. In this study, we have characterized a protein of the Rid7 subfamily, named Rid7C, in Nonomuraea gerenzanensis, an actinomycete that is characterized by the presence of two types of RNA polymerases. This is due to the coexistence in its genome of two RNA polymerase (RNAP) ß chain-encoding genes, rpoB(S) (the wild-type rpoB gene) and rpoB(R) (a specialist, mutant-type rpoB gene) that controls A40926 antibiotic production and a wide range of metabolic adaptive behaviors. Here, we found that expression of rpoB(R) is regulated posttranscriptionally by RNA processing in the 5' untranslated region (UTR) of rpoB(R) mRNA and that the endoribonuclease activity of Rid7C is responsible for mRNA processing, thereby overseeing several tracts of morphological and biochemical differentiation. We also provide evidence that Rid7C may be associated with RNase P M1 RNA, although M1 RNA is not required for rpoB(R) mRNA processing in vitro, and that Rid7C endoribonuclease activity is inhibited by A40926, suggesting the existence of a negative feedback loop in A40926 production and a role of the endogenous synthesis of A40926 in the modulation of biochemical differentiation in this microorganism. IMPORTANCE The YjgF/YER057c/UK114 family includes many proteins with diverse functions involved in detoxification, RNA maturation, and control of mRNA translation. We found that Rid7C is an endoribonuclease that is involved in processing of rpoB(R) mRNA, coding for a specialized RNA polymerase beta subunit that oversees morphological differentiation and A40926 antibiotic production in Nonomuraea gerenzanensis. Rid7C-mediated processing promotes rpoB(R) mRNA translation and antibiotic production, while Rid7C endoribonuclease activity is inhibited by A40926, suggesting a role of the endogenous synthesis of A40926 in modulation of biochemical differentiation in this microorganism. Finally, we show that recombinant Rid7C copurified with M1 RNA (the RNA subunit of RNase P) from Escherichia coli extract, suggesting a functional interaction between Rid7C and M1 RNA activities.

Comparative evaluation of various herbal extracts on biofilms of Streptococcus mutans and Scardovia wiggsiae: An in vitro study.

BACKGROUND: Owing to their strong antimicrobial properties, Helichrysum arenarium (HA), Anzer thyme (AT), and Stevia rebaudiana (SR) have been commonly used in medicine. AIM: This study aimed to evaluate antimicrobial activities of HA, AT, and SR against S. mutans and S. wiggsiae in biofilms formed on primary teeth. DESIGN: Fifty enamel samples were divided into two groups: mono-species biofilm and two-species biofilm. Each biofilm group was divided into five subgroups (n = 5): group 1, HA; group 2, AT; group 3, SR; group 4, CHX (positive control); and group 5, distilled water (negative control). Minimum inhibitory concentration and minimum bactericidal concentration were determined. The number of viable microorganisms was counted. The presence of microorganisms was examined using a scanning electron microscope, and mineral analysis was performed using energy-dispersive X-ray analysis. RESULTS: In the mono-species biofilm, CHX was significantly more effective against S. mutans than other groups (p < .001). Furthermore, HA, AT, and SR groups showed significantly lower colony counts of S. mutans than distilled water (p < .05). In the two-species biofilm group, AT, SR, and CHX were significantly more effective against S. wiggsiae than distilled water (p < .05). CONCLUSIONS: HA, AT, and SR have been suggested as effective natural alternatives to CHX against cariogenic bacteria.

Response of Rhodococcus cerastii IEGM 1278 to toxic effects of ibuprofen.

The article expands our knowledge on the variety of biodegraders of ibuprofen, one of the most frequently detected non-steroidal anti-inflammatory drugs in the environment. We studied the dynamics of ibuprofen decomposition and its relationship with the physiological status of bacteria and with additional carbon and energy sources. The involvement of cytoplasmic enzymes in ibuprofen biodegradation was confirmed. Within the tested actinobacteria, Rhodococcus cerastii IEGM 1278 was capable of complete oxidation of 100 µg/L and 100 mg/L of ibuprofen in 30 h and 144 h, respectively, in the presence of an alternative carbon source (n-hexadecane). Besides, the presence of ibuprofen induced a transition of rhodococci from single- to multicellular lifeforms, a shift to more negative zeta potential values, and a decrease in the membrane permeability. The initial steps of ibuprofen biotransformation by R. cerastii IEGM 1278 involved the formation of hydroxylated and decarboxylated derivatives with higher phytotoxicity than the parent compound (ibuprofen). The data obtained indicate potential threats of this pharmaceutical pollutant and its metabolites to biota and natural ecosystems.

Antimicrobial susceptibility testing of Eggerthella lenta blood culture isolates at a university hospital in Belgium from 2004 to 2018.

OBJECTIVES: Eggerthella lenta is a Gram-positive anaerobic bacillus that is an important cause of bloodstream infections. This study aims to test the susceptibility of Eggerthella lenta blood culture isolates to commonly used antibiotics for the empirical treatment of anaerobic infections. METHODS: In total, 49 positive blood cultures for Eggerthella lenta were retrospectively included from patients hospitalised at the Universitair Ziekenhuis Brussel, Belgium, between 2004 and 2018. Identification was done by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. Antimicrobial susceptibility testing was performed using the reference agar dilution method according to Clinical and Laboratory Standards Institute (CLSI) guidelines with Brucella agar supplemented with 5 µg/mL hemin, 1 µg/mL vitamin K1 and 5% laked sheep blood. The minimal inhibitory concentrations were interpreted using the EUCAST breakpoints. Clinical characteristics were collected by reviewing the patient's medical records. RESULTS: All isolates were susceptible to amoxicillin-clavulanate, metronidazole and meropenem. Eighty-eight % of them were susceptible to clindamycin and 94% (20% S, 74% I) were susceptible to piperacillin-tazobactam. The mean age of the patients was 64 (±20) and they showed a 30-day mortality of 27%. The source of infection was in 65.3% of the cases abdominal, 20.4% were sacral pressure ulcers and 14.3% were unknown causes. While all isolates were fully susceptible at standard dosing regimen to amoxicillin-clavulanate, most were only susceptible at increased exposure or resistant to piperacillin-tazobactam. CONCLUSIONS: Our results suggest to be careful with the use of piperacillin-tazobactam and clindamycin in the empirical treatment of Eggerthella lenta infections.

Synergistic Effect of Biosynthesized Silver Nanoparticles and Natural Phenolic Compounds against Drug-Resistant Fish Pathogens and Their Cytotoxicity: An In Vitro Study.

Fish pathogens causing disease outbreaks represent a major threat to aquaculture industry and food security. The aim of the presented study is to develop safe and effective bioactive agents against two bacterial isolates: Aeromonas hydrophila and Pseudomonas fluorescens. We employed a broth microdilution method to investigate the antibacterial effect of biosynthesized silver nanoparticles (AgNPs); rutin, a natural flavonoid extracted from Ruta graveneoles; and heliomycin, a secondary metabolite produced by marine actinomycetes AB5, as monotherapeutic agents. Moreover, AgNPs in combination with rutin (AgNP + R) and heliomycin (AgNPs + H) were examined for their synergistic effect. The cytotoxic effect of individual bioactive compounds and in combination with AgNPs was investigated on epithelioma papulosum cyprini (EPC) fish cell lines. Individual treatment of AgNPs, rutin, and heliomycin exhibited a dose-dependent antimicrobial activity against A. hydrophila and P. fluorescens. Rutin minimum inhibitory concentration (MIC) showed the lowest cytotoxicity when tested on EPC cell lines, while heliomycin MIC was highly cytotoxic. Combined subtherapeutic doses of AgNPs + R and AgNPs + H displayed additive and synergistic effects against A. hydrophila and P. fluorescens, respectively, with improved results and relative safety profile. The study findings demonstrate that a combination of AgNPs and natural bioactive compounds may represent novel therapeutics fighting fish pathogens potentially affecting the fish farming industry.

Lead contamination alters enzyme activities and microbial composition in the rhizosphere soil of the hyperaccumulator Pogonatherum crinitum.

Pogonatherum crinitum is a promising lead (Pb) hyperaccumulator; however, the effects of Pb contamination on P. crinitum rhizosphere soil enzymatic activities and microbial composition remain largely unexplored. Thus, an indoor experiment was conducted by cultivating P. crinitum seedlings and exposing them to four Pb concentrations (0, 1,000, 2000 and 3000 mg/kg Pb). Protease, urease, acid phosphatase and invertase activities were determined using standard methods while soil bacterial composition was determined by 16 S rDNA sequencing. The results showed that rhizosphere soil acid phosphatase activity significantly increased with increasing Pb concentration, while urease activity was significantly greater in rhizosphere soil contaminated with 1000 and 2000 mg/kg than in the control. There was a clear shift in bacterial composition during phytoremediation by P. crinitum. Compared to the control, Bacteroidetes was more abundant in all Pb-contaminated soils, Actinobacteria was more abundant in 1000 mg/kg Pb-treated soil, and Firmicutes was more abundant in 3000 mg/kg Pb-treated soil. Positive correlations were observed between dominant bacterial phyla and soil enzyme activities. Metabolic pathways, such as ABC transporter, quinine reductase, and ATP-binding protein were significantly increased in rhizosphere soil bacteria with Pb contamination. In conclusion, Pb contamination differentially influenced the activities of rhizosphere soil enzymes, specifically increasing acid phosphatase and urease activities, and alters the dominance of soil bacteria through up-regulation of genes related to some metabolic pathways. The strong correlations between dominant bacterial phyla and enzymatic activities suggest synergetic effects on the growth of P. crinitum during Pb contamination.

Whole genome sequencing and genome annotation of Dermacoccus abyssi strain HZAU 226 isolated from spoiled eggs.

Dermacoccus abyssi strain HZAU 226 is a spoilage bacterium isolated from eggs. So far, there are still few genomic resources available on the Dermacoccus abyssi. Here, we reported the complete genome sequence of Dermacoccus abyssi strain HZAU 226. High-quality DNA was extracted using the Qiagen kit, then single-molecule sequencing was performed by GridION sequencer. The raw data was quality-controlled and assembled to obtain the final genome, which consisted of a complete genome of 2,992,060 bp circular chromosome and a 64,524 bp plasmid. The structural and functional annotations of the genome were achieved through the analysis of different available databases, including antibiotic resistance genes, secondary metabolite synthesis genes and stress-related genes. Meanwhile, comparative genomic analyses of the strains were also performed. This is the first report on the complete genome of Dermacoccus abyssi, which will provide genomic resources for the study of spoilage bacteria in eggs.

Nutritional combinatorial impact on the gut microbiota and plasma short-chain fatty acids levels in the prevention of mammary cancer in Her2/neu estrogen receptor-negative transgenic mice.

Breast cancer is the second leading cause of cancer-related mortality in women. Various nutritional compounds possess anti-carcinogenic properties which may be mediated through their effects on the gut microbiota and its production of short-chain fatty acids (SCFAs) for the prevention of breast cancer. We evaluated the impact of broccoli sprouts (BSp), green tea polyphenols (GTPs) and their combination on the gut microbiota and SCFAs metabolism from the microbiota in Her2/neu transgenic mice that spontaneously develop estrogen receptor-negative [ER(-)] mammary tumors. The mice were grouped based on the dietary treatment: control, BSp, GTPs or their combination from beginning in early life (BE) or life-long from conception (LC). We found that the combination group showed the strongest inhibiting effect on tumor growth volume and a significant increase in tumor latency. BSp treatment was integrally more efficacious than the GTPs group when compared to the control group. There was similar clustering of microbiota of BSp-fed mice with combination-fed mice, and GTPs-fed mice with control-fed mice at pre-tumor in the BE group and at pre-tumor and post-tumor in the LC group. The mice on all dietary treatment groups incurred a significant increase of Adlercreutzia, Lactobacillus genus and Lachnospiraceae, S24-7 family in the both BE and LC groups. We found no change in SCFAs levels in the plasma of BSp-fed, GTPs-fed and combination-fed mice of the BE group. Marked changes were observed in the mice of the LC group consisting of significant increases in propionate and isobutyrate in GTPs-fed and combination-fed mice. These studies indicate that nutrients such as BSp and GTPs differentially affect the gut microbial composition in both the BE and LC groups and the key metabolites (SCFAs) levels in the LC group. The findings also suggest that temporal factors related to different time windows of consumption during the life-span can have a promising influence on the gut microbial composition, SCFAs profiles and ER(-) breast cancer prevention.

Comparison of culture-independent and dependent approaches for identification of native arsenic-resistant bacteria and their potential use for arsenic bioremediation.

Arsenic is a common contaminant in gold mine soil and tailings. Microbes present an opportunity for bio-treatment of arsenic, since it is a sustainable and cost-effective approach to remove arsenic from water. However, the development of existing bio-treatment approaches depends on isolation of arsenic-resistant microbes from arsenic contaminated samples. Microbial cultures are commonly used in bio-treatment; however, it is not established whether the structure of the cultured isolates resembles the native microbial community from arsenic-contaminated soil. In this milieu, a culture-independent approach using Illumina sequencing technology was used to profile the microbial community in situ. This was coupled with a culture-dependent technique, that is, isolation using two different growth media, to analyse the microbial population in arsenic laden tailing dam sludge based on the culture-independent sequencing approach, 4 phyla and 8 genera were identified in a sample from the arsenic-rich gold mine. Firmicutes (92.23%) was the dominant phylum, followed by Proteobacteria (3.21%), Actinobacteria (2.41%), and Bacteroidetes (1.49%). The identified genera included Staphylococcus (89.8%), Pseudomonas (1.25), Corynebacterium (0.82), Prevotella (0.54%), Megamonas (0.38%) and Sphingomonas (0.36%). The Shannon index value (3.05) and Simpson index value (0.1661) indicated low diversity in arsenic laden tailing. The culture dependent method exposed significant similarities with culture independent methods at the phylum level with Firmicutes, Proteobacteria and Actinobacteria, being common, and Firmicutes was the dominant phylum whereas, at the genus level, only Pseudomonas was presented by both methods. It showed high similarities between culture independent and dependent methods at the phylum level and large differences at the genus level, highlighting the complementarity between the two methods for identification of the native population bacteria in arsenic-rich mine. As a result, the present study can be a resource on microbes for bio-treatment of arsenic in mining waste.

The Preliminary Study on the Association Between PAHs and Air Pollutants and Microbiota Diversity.

The purpose of this study was to investigate the association among polycyclic aromatic hydrocarbons (PAHs) exposure and air pollutants and the diversity of microbiota. Daily average concentrations of six common air pollutants were obtained from China National Environmental Monitoring Centre. The PAHs exposure levels were evaluated by external and internal exposure detection methods, including monitoring atmospheric PAHs and urinary hydroxyl-polycyclic aromatic hydrocarbon (OH-PAH) metabolite levels. We analyzed the diversity of environmental and commensal bacterial communities with 16S rRNA gene sequencing and performed functional enrichment with Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and Kyoto Encyclopedia of Genes and Genomes (KEGG). Correlation analysis and logistic regression modeling were conducted to evaluate the relationship of PAHs levels with air pollutants and microbial diversity. Correlation analysis found that the concentrations of atmospheric PAHs were significantly positively correlated with those of PM10, NO2, and SO2. There also was a positive correlation between the abundance of the genus Micrococcus (Actinobacteria) and high molecular weight PAHs, and Bacillus, such as genera and low molecular weight PAHs in the atmosphere. Logistic regression showed that the level of urinary 1-OHPyrene was associated with childhood asthma after sex and age adjustment. The level of urinary 1-OHPyrene was significantly positively correlated with that of PM2.5 and PM10. In addition, the level of 1-OHPyrene was positively correlated with oral Prevotella-7 abundance. Functional enrichment analysis demonstrated that PAHs exposure may disturb signaling pathways by the imbalance of commensal microbiota, such as purine metabolism, pyrimidine metabolites, lipid metabolism, and one carbon pool by folate, which may contribute to public health issues. Our results confirmed that atmospheric PAHs and urinary 1-OHPyrene were correlated with part of six common air pollutants and indicated that PAHs pollution may alter both environmental and commensal microbiota communities associated with health-related problems. The potential health and environmental impacts of PAHs should be further explored.

Eggerthella lenta bloodstream infections: two cases and review of the literature.

Eggerthella lenta is an emerging and uncommon human pathogen that has been under recognized due to the limitations of phenotypic identification. Here we describe two cases of bacteremia caused by E. lenta and summarize the results of antimicrobial susceptibility testing according to some previous literatures, which illustrate the importance of identification and treatment of unusual organisms. The most reliable antibiotic treatment options to E. lenta appear to be metronidazole, amoxicillin-clavulanate, carbapenems, vancomycin, cefoxitin, chloramphenicol and clindamycin.

Discrimination of heavy metal acclimated environmental strains by chemometric analysis of FTIR spectra.

Heavy metal acclimated bacteria are profoundly the preferred choice for bioremediation studies. Bacteria get acclimated to toxic concentrations of heavy metals by induction of specific enzymes and genetic selection favoring new metabolic abilities leading to activation of one or several of resistance mechanisms creating bacterial populations with differences in resistance profile and/or level. Therefore, to use in bioremediation processes, it is important to discriminate acclimated bacterial populations and choose a more resistant strain. In this study, we discriminated heavy metal acclimated bacteria by using Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) spectroscopy and multivariate analysis methods namely Hierarchical Cluster Analysis (HCA), Principal Component Analysis (PCA) and Soft Independent Modeling of Class Analogy (SIMCA). Two acclimation methods, acute and gradual, were used which cause differences in molecular changes resulting in bacterial populations with different molecular and resistance profiles. Brevundimonas sp., Gordonia sp., and Microbacterium oxydans were exposed to the toxic concentrations of Cd (30 µg/ml) or Pb (90 µg/ml) by using broth medium as a growth media. Our results revealed that PCA and HCA clearly discriminated the acute-acclimated, gradual-acclimated, and control bacteria from each other in protein, carbohydrate, and whole spectral regions. Furthermore, we classified acclimated (acute and gradual) and control bacteria more accurately by using SIMCA with 99.9% confidence. This study demonstrated that heavy metal acclimated and control group bacteria can be discriminated by using chemometric analysis of FTIR spectra in a powerful, cost-effective, and handy way. In addition to the determination of the most appropriate acclimation procedure, this approach can be used in the detection of the most resistant bacterial strains to be used in bioremediation studies.

Studies on nutritional intervention of rice starch- oleic acid complex (resistant starch type V) in rats fed by high-fat diet.

In this study, rice starch-oleic acid complex with well-controlled digestibility was chosen as a supplementary diet for rats fed with high fat diet. Our results demonstrated that rice starch-oleic acid complex supplementation significantly decreased body weight, improved serum lipid profiles, hepatic metabolism and altered the composition of gut microbiota of rats, which might be related to the higher resistant starch (RS) level. Interestingly, rice starch-oleic acid complex supplementation contributed to the proliferation and growth of butyrate-producing bacteria. The Spearman's correlation analysis revealed that the genus Turicibacter and Romboutsia genus were positively correlated to HDL-c and SOD level. Meanwhile, based on the metagenomic data, Bifidobacteria genus might be a main primary degrader after rice starch-oleic acid complex intake, which was associated with the changes of key starch-degradation enzymes. Overall, our results provided basic data for the rational design of rice starch-based foods with nutritional functions and physiological benefits.

Microbial diversity and co-occurrence patterns in deep soils contaminated by polycyclic aromatic hydrocarbons (PAHs).

Numerous studies have enriched our knowledge of the microbial community composition and metabolic versatility of contaminated soil. However, there remains a substantial gap regarding the bioassembly patterns of the indigenous microbial community distribution in contaminated deep soils. Herein, the indigenous microbial community structure diversity, function, and co-occurrence relationships in aged PAH-contaminated deep soil collected from an abandoned chemical facility were investigated using high-throughput sequencing. The results showed that the dominant phyla in all samples were responsible for PAH degradation and included Proteobacteria (20.86%-81.37%), Chloroflexi (2.03%-28.44%), Firmicutes (3.06%-31.16%), Actinobacteria (2.92%-11.91%), Acidobacteria (0.41%-12.68%), and Nitrospirae (0.81%-9.21%). Eighty biomarkers were obtained by linear discriminant analysis of effect size (LEfSe), and most of these biomarkers were PAH degraders. Functional predictions using Tax4Fun indicated that the aged contaminated soil has the potential for PAH degradation. Statistical analysis showed that in contrast with the PAH concentration, edaphic properties (nutrients and pH) were significantly correlated (r > 0.25, P < 0.01) with the bacterial community and functional composition. Co-occurrence network analysis (modularity index of 0.781) revealed non-random assembly patterns of the bacterial communities in the PAH-contaminated soils. The modules in the network were mainly involved in carbon and nitrogen cycles, organic substance degradation, and biological electron transfer processes. Microbes from the same module had strong ecological linkages. Additionally, SAR202 clade, Thermoanaerobaculum, Nitrospira, and Xanthomonadales, which were identified as keystone species, played an irreplaceable role in the network. Overall, our results suggested that environmental factors such as nutrients and pH, together with ecological function, are the main factors driving the assembly of microbial communities in aged PAH-contaminated deep soils.

Relevance of Dermabacter hominis isolated from clinical samples, 2012-2016: a retrospective case series.

We investigated the clinical relevance of Dermabacter hominis isolated from samples of 108 patients. Polymicrobial growth was evident in 88% of specimens. Isolation of D. hominis was of definitive or possible significance in only 14% of patients. Vancomycin remains the drug of choice given a penicillin resistance rate of 84%.

Prebiotic properties of different polysaccharide fractions from Artemisia sphaerocephala Krasch seeds evaluated by simulated digestion and in vitro fermentation by human fecal microbiota.

Artemisia sphaerocephala Krasch polysaccharide (ASKP) and its two fractions-60P (branched xylan) and 60S (branched glucomannan), were subjected to simulated gastrointestinal digestion and in vitro fermentation by human fecal microbiota. The results showed that all polysaccharide fractions could transit through gastrointestinal tract without dramatic degradation and be utilized by gut microbiota. ASKP exhibited the highest depletion rate and highest capability to decrease the pH than its fractions. Meanwhile, 60S showed the stronger capability to increase the production of propionic acid and reduce the ratio of acetic acid to propionic acid. At the phylum level, all polysaccharides efficiently reduced the Firmicutes/Bacteroidetes ratio and relative abundance of Proteobacteria, with ASKP being the most capable to suppress the proliferation of Proteobacteria. At the genus level, ASKP and 60P markedly promoted the growth of Bacteroidetes, and 60S promoted the growth of Parabacteroides and Collinsella. Prediction on metabolic function revealed that polysaccharide administration could dramatically change the metabolic profile of bacteria compared with fructooligosaccharides. Besides, all the polysaccharides dramatically promoted the bile acid metabolism. Compared with 60S, ASKP and 60P showed stronger ability to suppress the metabolisms on carbohydrate and amino acid. In summary, both ASKP and its two fractions showed the prebiotic potentials.

The Antitumor Agent Ansamitocin P-3 Binds to Cell Division Protein FtsZ in Actinosynnema pretiosum.

Ansamitocin P-3 (AP-3) is an important antitumor agent. The antitumor activity of AP-3 is a result of its affinity towards ß-tubulin in eukaryotic cells. In this study, in order to improve AP-3 production, the reason for severe growth inhibition of the AP-3 producing strain Actinosynnema pretiosum WXR-24 under high concentrations of exogenous AP-3 was investigated. The cell division protein FtsZ, which is the analogue of ß-tubulin in bacteria, was discovered to be the AP-3 target through structural comparison followed by a SPR biosensor assay. AP-3 was trapped into a less hydrophilic groove near the GTPase pocket on FtsZ by hydrogen bounding and hydrophobic interactions, as revealed by docking analysis. After overexpression of the APASM_5716 gene coding for FtsZ in WXR-30, the resistance to AP-3 was significantly improved. Moreover, AP-3 yield was increased from 250.66 mg/L to 327.37 mg/L. After increasing the concentration of supplemented yeast extract, the final yield of AP-3 reached 371.16 mg/L. In summary, we demonstrate that the cell division protein FtsZ is newly identified as the bacterial target of AP-3, and improving resistance is an effective strategy to enhance AP-3 production.

Azolla filiculoides L. as a source of metal-tolerant microorganisms.

The metal hyperaccumulator Azolla filiculoides is accompanied by a microbiome potentially supporting plant during exposition to heavy metals. We hypothesized that the microbiome exposition to selected heavy metals will reveal metal tolerant strains. We used Next Generation Sequencing technique to identify possible metal tolerant strains isolated from the metal-treated plant (Pb, Cd, Cr(VI), Ni, Au, Ag). The main dominants were Cyanobacteria and Proteobacteria constituting together more than 97% of all reads. Metal treatment led to changes in the composition of the microbiome and showed significantly higher richness in the Pb-, Cd- and Cr-treated plant in comparison with other (95-105 versus 36-44). In these treatments the share of subdominant Actinobacteria (0.4-0.8%), Firmicutes (0.5-0.9%) and Bacteroidetes (0.2-0.9%) were higher than in non-treated plant (respectively: 0.02, 0.2 and 0.001%) and Ni-, Au- and Ag-treatments (respectively: <0.4%, <0.2% and up to 0.2%). The exception was Au-treatment displaying the abundance 1.86% of Bacteroidetes. In addition, possible metal tolerant genera, namely: Acinetobacter, Asticcacaulis, Anabaena, Bacillus, Brevundimonas, Burkholderia, Dyella, Methyloversatilis, Rhizobium and Staphylococcus, which form the core microbiome, were recognized by combining their abundance in all samples with literature data. Additionally, the presence of known metal tolerant genera was confirmed: Mucilaginibacter, Pseudomonas, Mycobacterium, Corynebacterium, Stenotrophomonas, Clostridium, Micrococcus, Achromobacter, Geobacter, Flavobacterium, Arthrobacter and Delftia. We have evidenced that A. filiculoides possess a microbiome whose representatives belong to metal-resistant species which makes the fern the source of biotechnologically useful microorganisms for remediation processes.