Phosphorus (P) is an essential nutrient for plant growth but the global supply is limited, and over-reliance on chemical phosphate fertilizers can lead to soil pollution and ecological imbalance. Phosphate-solubilizing bacteria (PSB) can convert insoluble P in the soil into plant-available forms and enhance the P utilization efficiency of crops. The application of PSB can also improve the soil ecological environment and contribute to the sustainable development of agriculture. This review systematically summarizes the diversity and distribution of PSB. It comprehensively investigates the mechanisms through which PSB enhance soil P utilization efficiency, focusing on the following aspects: the acid-mediated solubilization of inorganic P, the enzymatic hydrolysis of organic P, the interactions between PSB and plant roots, and the interactions between PSB and rhizosphere microorganisms. Furthermore, recent advances in the development and application of PSB-based biofertilizers are also reviewed. Potential future research directions and the anticipated challenges within this field are also discussed, to develop innovative strategies for alleviating P deficiency in agricultural soils.
Marija Ćorović, Anja Petrov Ivanković, Ana Milivojević
et al.
<b>Background/Objectives</b>: Numerous intrinsic and extrinsic stressors can disrupt the balance of the skin microbiome, leading to the development of various skin diseases. It has been proven that coagulase-negative staphylococci (CoNS) are important commensals for maintaining skin microbiome homeostasis and fighting cutaneous pathogens such as <i>Staphylococcus aureus</i> (<i>S. aureus</i>). Here, we examined the influence of polyphenol-rich enzymatic blackcurrant extract (EBCE) on pathogenic coagulase-positive <i>S. aureus</i> strains and beneficial CoNS, like <i>Staphylococcus epidermidis</i> (<i>S. epidermidis</i>), to explore its potential for rebalancing the skin microbiota. <b>Methods</b>: The polyphenol profile of EBCE was determined by ultra-high-pressure liquid chromatography–tandem mass spectrometry. Microwell plate assays were employed to study the effect of EBCE on five <i>S. aureus</i> strains isolated from the skin of atopic dermatitis patients. An in vitro human <i>stratum corneum</i> model was used to test its effect on mixed bacterial cultures. <b>Results</b>: EBCE inhibited the growth of all tested <i>S. aureus</i> strains by 80–100% at the highest tested concentration after 7 h. No microbial growth was observed at the highest tested EBCE concentration using the <i>stratum corneum</i> model inoculated with one selected pathogen (<i>S. aureus</i> SA-DUS-017) and one commensal laboratory strain (<i>S. epidermidis</i> DSM 20044). The lowest tested concentration did not interfere with <i>S. aureus</i> growth but strongly stimulated the growth of <i>S. epidermidis</i> (~300-fold colony forming unit increase). In addition, low EBCE concentrations strongly stimulated CoNS growth in microbiome samples taken from the armpits of healthy volunteers that were spiked with <i>S. aureus</i> SA-DUS-017. <b>Conclusions</b>: These preclinical data support further testing of EBCE-enriched topical preparations as potential cutaneous prebiotics in human studies.
Shihai Huang, Luciana Girotto Gentil, Colleen Schmidt
et al.
ABSTRACT Primary high-risk human papillomavirus (HPV) testing is recommended for cervical cancer screening due to its sensitivity and high negative predictive value. Most of the cervical cancers are caused by HPV16 and HPV18, and their presence has been used to guide patient management. Here, we compared the clinical performance of the Alinity m HR HPV, cobas 4800 HPV, and cobas 6800 HPV assays in the context of cervical cancer screening. Clinical sensitivity and specificity were evaluated with 125 ≥CIN3 (cervical intraepithelial neoplasia grade 3) cases and 244 controls (≤CIN1). The genotype agreements between the assays were also evaluated for the case and control groups. The clinical sensitivities were 96.0% for Alinity m and cobas 6800 assays, and 95.2% for cobas 4800 assay. The clinical specificities observed were 67.6%, 68.0%, and 68.4% for Alinity m, cobas 6800, and cobas 4800 assays, respectively. Overall, the three HPV assays demonstrated similar clinical performance. In the ≥CIN3 group, genotype-specific positive agreement was ≥98.4% between Alinity m and cobas 4800 assays, and ≥85.7% between cobas 6800 and cobas 4800 assays. In the ≤CIN1 group, overall positive agreement among the three assays was ≥94.8%. This study showed similar clinical sensitivity and specificity for Alinity m HR HPV, cobas 4800 HPV, and cobas 6800 HPV assays. Alinity m was more specific in detecting HPV16 and HPV18, which could reduce unnecessary immediate referrals of women to colposcopy.IMPORTANCEThis study provides evidence that the Alinity m HR human papillomavirus (HPV) assay has similar clinical performance in comparison with the cobas 4800 HPV and cobas 6800 HPV, two widely used tests. Validation of HPV assays in a clinical setting is crucial to ensure that they can provide a balanced sensitivity and specificity for detecting high-grade cervical intraepithelial neoplasia, potentially improving patient management by enabling proper follow-up or treatment and avoiding unnecessary procedures.
Tetiana A. Berezina, Oleksandr O. Berezin, Evgen V. Novikov
et al.
Background: Atrial fibrillation (AF) is common complication of heart failure with preserved ejection fraction (HFpEF) that sufficiently intervenes in the prognosis. The aim of the study is a) to investigate the possible discriminative value of adropin for newly onset AF in patients with HFpEF without a previous history of AF and who are being treated in accordance with conventional guideline and b) to compare it with predictive potencies of conventionally used predictors. Methods: A total of 953 patients with HFpEF who had sinus rhythm on ECG were enrolled in the study. The course of the observation was 3 years. Echocardiography and assessment of conventional hematological, biochemical parameters and biomarker assay including N-terminal brain natriuretic pro-peptide (NT-proBNP), high-sensitivity cardiac troponin T, tumor necrosis factor-alpha, high-sensitivity C-reactive protein (hs-CRP), galectin-3, interleukin-6, soluble suppressor tumorigenisity-2 (sST2) and adropin, were performed at baseline. Results: Incident atrial fibrillation was found in 172 patients with HFpEF, whereas 781 had sinus rhythm. In unadjusted rough Cox regression model, age ≥ 75 years, type 2 diabetes mellitus, chronic kidney disease (CKD) stages 1–3, left atrial volume index (LAVI) ≥ 40 mL/m<sup>2</sup>, NT-proBNP ≥ 1440 pmol/mL, hs-CRP ≥ 5.40 mg/L, adropin ≤ 2.95 ng/mL, sST2 ≥ 15.5 ng/mL were identified as the predictors for new onset AF in HFpEF patients. After adjusting for age ≥ 75 years, a presence of type 2 diabetes mellitus and CKD stages 1–3, the levels of NT-proBNP ≥ 1440 pmol/mL and adropin ≤ 2.95 ng/mL were independent predictors of new onset AF in patients HFpEF. We also found that discriminative value of adropin was superior to NT-proBNP, while adding adropin to NT-proBNP did not improve predictive information of adropin alone. Conclusions: adropin ≤ 2.95 ng/mL presented more predictive information than NT-proBNP ≥ 1440 pmol/mL alone for new cases of AF in symptomatic patients with HFpEF, whereas the combination of both biomarkers did not improve the predictive ability of adropin alone.
R. G. Vyshnavi, R. K. Samaiya, Anita Babbar
et al.
The study was conducted during the rabi seasons (November) of 2021– (April) 2022 and 2022 (November) –2023 (April) in Jabalpur, Madhya Pradesh, India aimed to explore chickpea germplasm responses to high temperature stress under varied sowing conditions. Thirty-two germplasm lines and eight elite varieties were sown under normal and late conditions to coincide with heat stress occurrence (>32°C). The investigation done on phenological data impacted by sowing dates, revealed significant differences between normal and late sowing conditions across critical growth stages. Temporal disparities resulted in an approximate 8-day reduction in days to 50% flowering (DFF), 7 days in days to pod formation (DPF), 9 days in days to seed formation (DSF), and 12 days in days to field maturity (DFM). Conversely, longer-duration genotypes experienced a reduction of around 6 days in DFF, DPF, DSF, and 14 days in DFM. Yield attributes among genotypes varied significantly between different sowing conditions. Under normal (D1) conditions, genotypes exhibited adequate seed yield (kg/ha-1), while late-sown (D2) conditions resulted in considerable percentage decrements of 40.2% reduction in the yield. Post hoc Duncan’s New Multiple Range Test (DNMRT) analysis indicated substantial variability among genotypes for all traits, except for primary and secondary branches, observed across both sowing conditions. The correlation analysis uncovered nuanced associations between phenological stages and yield attributes, emphasizing the complexity of chickpea cultivation dynamics. This study provides valuable insights into optimizing chickpea germplasm for high temperature stress resilience, contributing to the ongoing efforts for sustainable and climate-resilient agriculture.
Ahmad Zulkefly, Wan Norlina Wan Azman, Julia Omar
et al.
This case-control study, conducted at the Hospital USM BestARi unit, aimed to identify the serum metabolic fingerprint among individuals with breast lumps and healthy controls, and to discover potential biomarkers. Serum samples from healthy controls, benign breast lump patients, and malignant breast lump patients were analyzed using proton nuclear magnetic resonance spectroscopy (1H NMR). A multivariate data analysis approach was employed, with the OPLS-DA and clustered heat map techniques effectively differentiating between the three groups. The study revealed significant metabolite variations across the groups and proposed D-glucose, glycerol, and glycine as potential biomarkers for breast cancer diagnosis. Metabolic pathways such as alanine, aspartate, glutamate metabolism, and glycine, serine, and threonine metabolism were implicated. The metabolomics approach coupled with multivariate analysis successfully identified key metabolites leading to group separation and suggested altered metabolic pathways. However, further research and integration with other ‘omics’ technologies are necessary for clinical translation.
Sharada Swaminathan, Tatiana Scorza, Alexis Yero
et al.
BackgroundThe differentiation and function of immunosuppressive regulatory T cells (Tregs) is dictated by the master transcription factor FoxP3. During HIV infection, there is an increase in Treg frequencies in the peripheral blood and lymphoid tissues. This accentuates immune dysfunction and disease progression. Expression of FoxP3 by thymic Tregs (tTregs) is partially controlled by TGF-β. This cytokine also contributes to Treg development in the peripheral blood and lymphoid tissues. Although TGF-β mediates lymphoid tissue fibrosis and peripheral Treg differentiation in HIV-infected individuals, its role in the induction and maintenance of Tregs within the thymus during HIV infection remains unclear.MethodsThymocytes were isolated from fresh human thymic tissues obtained from pediatric patients undergoing cardiac surgery. Infection by both R5- and X4-tropic HIV-1 strains and TGF-β treatment of human thymocytes was performed in an in vitro co-culture model with OP9-DL1 cells expressing Notch ligand delta-like 1 without T cell receptor (TCR) activation.ResultsDespite high expression of CCR5 and CXCR4 by tTregs, FoxP3 + CD3highCD8- thymocytes were much less prone to in vitro infection with R5- and X4-tropic HIV strains compared to FoxP3-CD3highCD8- thymocytes. As expected, CD3highCD4+ thymocytes, when treated with TGF-β1, upregulated CD127 and this treatment resulted in increased FoxP3 expression and Treg differentiation, but did not affect the rate of HIV infection. FoxP3 expression and Treg frequencies remained unchanged following in vitro HIV infection alone or in combination with TGF-β1.ConclusionFoxP3 expression and tTreg differentiation is not affected by in vitro HIV infection alone or the combination of in vitro HIV infection and TGF-β treatment.
Summary: Our knowledge of the regulatory mechanisms that govern the replication of the rubella virus (RV) in human cells is limited. To gain insight into the host-pathogen interaction, we conducted a loss-of-function screening using the CRISPR-Cas9 system in the human placenta-derived JAR cells. We identified sphingomyelin synthase 1 (SGMS1 or SMS1) as a susceptibility factor for RV infection. Genetic knockout of SGMS1 rendered JAR cells resistant to infection by RV. The re-introduction of SGMS1 restored cellular susceptibility to RV infection. The restricted step of RV infection was post-endocytosis processes associated with the endosomal acidification. In the late phase of the RV replication cycle, the maintenance of viral persistence was disrupted, partly due to the attenuated viral gene expression. Our results shed light on the unique regulation of RV replication by a host factor during the early and late phases of viral life cycle.
Lung adenocarcinoma (LADC) is a prevalent type of lung cancer that is associated with lung and gut microbiota. However, the interactions between these microbiota and cancer development remain unclear. In this study, a microbiome study was performed on paired fecal and bronchoalveolar lavage fluid (BALF) samples from 42 patients with LADC and 64 healthy controls using 16S rRNA gene amplicon and shotgun metagenome sequencing, aiming to correlate the lung and gut microbiota with LADC. Patients with LADC had reduced α-diversity in the gut microbiome and altered β-diversity compared with healthy controls, and the abundances of <i>Flavonifractor</i>, <i>Eggerthella</i>, and <i>Clostridium</i> were higher in the gut microbiome of LADC patients. The increased abundance of microbial species, such as <i>Flavonifractor plautii</i>, was associated with advanced-stage LADC and a higher metastasis rate. Phylogenetically, <i>Haemophilus parainfluenzae</i> was the most frequently shared taxon in the lung and gut microbiota of LADC patients. Gut microbiome functional pathways involving leucine, propanoate, and fatty acids were associated with LADC progression. In conclusion, the low diversity of the gut microbiota and the presence of <i>H. parainfluenzae</i> in gut and lung microbiota were linked to LADC development, while an increased abundance of <i>F. plautii</i> and the enriched metabolic pathways could be associated with the progression of LADC.
This study aimed to detect the presence of urinary schistosomiasis, the associated risk factors and its impact on blood parameters among Almajiris in two selected rural communities of Kaduna State. Urine samples were collected from 193 Almajiri subjects and processed by sedimentation method and examined under the microscope. Blood samples were also collected from the subjects and processed using SWELAB auto-analyser for full blood count. A well-structured knowledge, attitude and practice (KAP) questionnaire was administered to the subjects and used to obtain demographic and other associated risk factors. The overall prevalence of urinary schistosomiasis in the two study areas was 16.1%. Bomo recorded 17.5%, while Rafin Guza recorded 22.9% prevalence respectively. Subjects in the age group 11–16 years had a higher prevalence of 33% (p<0.05). Among the risk factors assessed, subjects that visit the stream for swimming and used well water recorded a higher prevalence of (33.7%) and (17.2%) respectively (p<0.05). Awareness about the disease revealed higher prevalence (p<0.05). Prevalence of the infection among the subjects was also found to be significantly associated with white blood cell (WBC) count, lymphocyte, and monocyte count (p<0.05). The present study identified the study areas to represent moderate–risk community for urinary schistosomiasis. The study advocates the use of mass treatment with Praziquantel to help in reducing the infection level and controlling transmission of the disease.
Irina Marcovich, Nicholas K. Baer, Olga Shubina-Oleinik
et al.
Gene therapy for genetic hearing loss is an emerging therapeutic modality for hearing restoration. However, the approach has not yet been translated into clinical application. To further develop inner-ear gene therapy, we engineered a novel mouse model bearing a human mutation in the transmembrane channel-1 gene (<i>Tmc1</i>) and characterized the auditory phenotype of the mice. TMC1 forms the mechanosensory transduction channel in mice and humans and is necessary for auditory function. We found that mice harboring the equivalent of the human p.N199I mutation (p.N193I) had profound congenital hearing loss due to loss of hair cell sensory transduction. Next, we optimized and screened viral payloads packaged into AAV9-PHP.B capsids. The vectors were injected into the inner ears of <i>Tmc1<sup>Δ/Δ</sup></i> mice and the new humanized <i>Tmc1</i>-p.N193I mouse model. Auditory brainstem responses (ABRs), distortion product otoacoustic emissions (DPOAEs), cell survival, and biodistribution were evaluated in the injected mice. We found broad-spectrum, durable recovery of auditory function in <i>Tmc1</i>-p.N193I mice injected with AAV9-PHP.B-<i>CB6-hTMC1-WPRE</i>. ABR and DPOAE thresholds were equivalent to those of wild-type mice across the entire frequency range. Biodistribution analysis revealed viral DNA/RNA in the contralateral ear, brain, and liver but no overt toxicity. We conclude that the AAV9-PHP.B-<i>CB6-hTMC1-WPRE</i> construct may be suitable for further development as a gene therapy reagent for treatment of humans with genetic hearing loss due to recessive <i>TMC1</i> mutations.
Chaurasia Mukul, Agrawa Neha, Chourasia Ankita
et al.
Background: Staphylococcus aureus (S. aureus) and its resistant form methicillinresistant S. aureus (MRSA) is one of the most common nosocomial pathogens causing a wide range of infections in humans. The anterior nares are the main ecological niche for S. aureus. Nasal carriage of S. aureus acts as an important reservoir of infection among the colonised healthcare workers and they transmit the infection to the community. The aim of the present study was to estimate the nasal colonisation of S. aureus (with special reference to MRSA) in healthcare workers (doctors and nursing staff) and its antibiotic susceptibility pattern. Methods: A descriptive study was planned in the Department of Microbiology, JLN Medical College, Ajmer (Rajasthan, India) after due approval from the institutional ethics committee. A total of 170 healthcare workers of either sex aged between 18 to 60 years were screened for S. aureus. Identification was done using standard microbiological techniques, by studying their morphology, colony and biochemical characteristics. MRSA was detected by cefoxitin disc diffusion test, oxacillin disc diffusion test, minimum inhibitory concentration (MIC) of oxacillin by E-test and oxacillin screen agar test. The observations were described in proportions and Chisquared test was used to find independence. Statistical significance was considered at 5 %. Results: Among 170 samples, 159 (93.53 %) samples (50 doctors and 109 nursing staff) had staphylococci colonisation. Among these 159 isolates, 34 (21.38 %) were S. aureus. Further, 8 (5.03 %) S. aureus isolates were resistant to both cefoxitin and oxacillin and had oxacillin MIC values ≥ 4 µg/mL and were considered MRSA. All the MRSA were detected in the nursing staff (males: 5.50 %, females: 1.83 %). All S. aureus and MRSA isolates were found sensitive to linezolid, vancomycin and mupirocin (minimum inhibitory concentration ≤ 4 µg/mL). Conclusion: Screening and treatment of healthcare workers colonised with MRSA should be an important component of hospital infection control policy. These measures will prevent spread of infection to patients and the community and thereby reduce the morbidity, mortality and healthcare costs associated with nosocomial infections.
Plant-associated microbiota plays an important role in plant disease resistance. Bacterial wilt resistance of tomato is a function of the quantitative trait of tomato plants; however, the mechanism underlying quantitative resistance is unexplored. In this study, we hypothesized that rhizosphere microbiota affects the resistance of tomato plants against soil-borne bacterial wilt caused by Ralstonia solanacearum. This hypothesis was tested using a tomato cultivar grown in a defined soil with various microbiota transplants. The bacterial wilt-resistant Hawaii 7996 tomato cultivar exhibited marked suppression and induction of disease severity after treatment with upland soil-derived and forest soil-derived microbiotas, respectively, whereas the transplants did not affect the disease severity in the susceptible tomato cultivar Moneymaker. The differential resistance of Hawaii 7996 to bacterial wilt was abolished by diluted or heat-killed microbiota transplantation. Microbial community analysis revealed the transplant-specific distinct community structure in the tomato rhizosphere and the significant enrichment of specific microbial operational taxonomic units (OTUs) in the rhizosphere of the upland soil microbiota-treated Hawaii 7996. These results suggest that the specific transplanted microbiota alters the bacterial wilt resistance in the resistant cultivar potentially through a priority effect.
Vin Tangpricha, Ellen M. Smith, Jose Binongo
et al.
Vitamin D deficiency is highly prevalent in children and adults with cystic fibrosis (CF). Recent studies have found an association between vitamin D status and risk of pulmonary exacerbations in children and adults with CF. The ongoing Vitamin D for enhancing the Immune System in Cystic fibrosis (DISC) study, a multi-center, double-blind, randomized, placebo-controlled trial, will test the hypothesis of whether high dose vitamin D given as a single oral bolus of 250,000 IU to adults with CF during a pulmonary exacerbation followed by a maintenance dose of vitamin D will improve time to next pulmonary exacerbation and re-hospitalization, improve survival and lung function compared to placebo and reduce the rates of pulmonary exacerbation. Subjects will be randomized 1:1 at each clinical site to vitamin D or placebo within 72 h of hospital admission for pulmonary exacerbation. Clinical follow-up visits will occur at 1, 2, 3, and 7 days, and 1, 3, 6 and 12 months after randomization. Blood and sputum will be collected and determination of clinical outcomes will be assessed at each visit. The primary endpoint will be the time to next pulmonary exacerbation requiring antibiotics, re-hospitalization or death. The secondary endpoints will include lung function assessed by forced expiratory volume in 1 s (FEV1), blood markers of inflammatory cytokines, anti-microbial peptide expression by peripheral blood mononuclear cells and circulating concentrations in blood. Other exploratory endpoints will examine the phenotype of neutrophils and monocyte/macrophages in sputum. Nutritional status will be assessed by 3 day food records and food frequency questionnaire.
Aims and objectives: Bone and joint infections due to environmental mycobacteria are rare and can develop very slowly. The source for these outbreaks is generally tap water supplies. In the present review, the focus is on a large outbreak of Mycobacterium xenopi spinal infections in patients who had undergone surgical microdiscectomy for disc hernia in a French hospital. Surprisingly, a patient was diagnosed with a M. xenopi discitis with secondary extension to the sacroiliac joint 15 years after spinal surgery. The findings of a national investigation launched by health authorities to determine the number of the bone and joint infections due to opportunistic mycobacteria are described in this study.
Methods: National health authorities launched a retrospective investigation in patients who were exposed to M. xenopi contamination in that hospital. Moreover, a national survey was conducted across all French laboratories to collect information on bone and joint cases due to opportunistic mycobacteria. The National Reference Center for Mycobacteria investigated hospital tap water supplies and developed a species-specific probe for the rapid identification of M. xenopi.
Results: Bone and joint infections, with the exception of the episode of the clinic where the large M. xenopi outbreak occurred, are rare in France. A very small number of cases, all sporadic, were detected and linked to an invasive procedure. In addition to M. xenopi, mycobacterial species involved are Mycobacterium marinum, Mycobacterium chelonae, Mycobacterium fortuitum, Mycobacterium avium and Mycobacterium kansasii. Despite awareness of laboratories to mycobacterial infections, no significant increase in iatrogenic infections has been demonstrated in care facilities. The source of infection of the large outbreak of spondylitis due to M. xenopi was traced to deficient hygiene practices and a high concentration of M. xenopi in the hospital tap water.
Conclusions: Failures in hygiene practices could result in an uncontrolled outbreak of nosocomial infection. Patients who have been exposed to an iatrogenic infectious hazard should be screened promptly when symptoms develop.
Marcus eFulde, Marcus eFulde, Joerg eWillenborg
et al.
The arginine-ornithine antiporter (ArcD) is part of the Arginine Deiminase System (ADS), a catabolic, energy-providing pathway found in a variety of different bacterial species, including the porcine zoonotic pathogen Streptococcus suis. The ADS has recently been shown to play a role in the pathogenicity of S. suis, in particular in its survival in host cells. The contribution of arginine and arginine transport mediated by ArcD, however, has yet to be clarified. In the present study, we showed by experiments using [U-13C6]arginine as a tracer molecule that S. suis is auxotrophic for arginine and that bacterial growth depends on the uptake of extracellular arginine. To further study the role of ArcD in arginine metabolism, we generated an arcD-specific mutant strain and characterized its growth compared to the wild-type (WT) strain, a virulent serotype 2 strain. The mutant strain showed a markedly reduced growth rate in chemically defined media supplemented with arginine when compared to the WT strain, indicating that ArcD promotes arginine uptake. To further evaluate the in vivo relevance of ArcD, we studied the intracellular bacterial survival of the arcD mutant strain in an epithelial cell culture infection model. The mutant strain was substantially attenuated, and its reduced intracellular survival rate correlated with a lower ability to neutralize the acidified environment. Based on these results, we propose that ArcD, by its function as an arginine-ornithine antiporter, is important for supplying arginine as substrate of the ADS and, thereby, contributes to biological fitness and virulence of S. suis in the host.
Mass uncontrolled use of antibiotics, environmentaldegradation, large amount of stress situations cause re-duction of adaptive abilities of human body, activate thesympathetic-adrenal system, which, in turn, causes theneurohumoral changes due to the imbalance of neuro-transmitters production, affecting specific and nonspe-cific resistance of the organism, as well as the microflora.According to WHO data, the number of people with dis-orders of immune system is constantly increasing. Thatleads to exacerbation of chronic diseases, including thosecaused by opportunistic pathogens. Thereby, it is veryimportant to develop appropriate methods for macroor-ganism’s optimum microflora restoring. The review sum-marizes the scientific data about composition, mecha-nisms of action and drug formulations of probiotics, pre-biotics and synbiotics. The probable complications aftertaking these drugs are described. The main problems as-sociated with the production and standardization of pro-biotic preparations and perspective directions aimed atthe normalization of microbial ecology are presented inthe article.
<p>Abstract</p> <p>Background</p> <p>The substitution of plastics based on fossil raw material by biodegradable plastics produced from renewable resources is of crucial importance in a context of oil scarcity and overflowing plastic landfills. One of the most promising organisms for the manufacturing of medium-chain-length polyhydroxyalkanoates (mcl-PHA) is <it>Pseudomonas putida </it>KT2440 which can accumulate large amounts of polymer from cheap substrates such as glucose. Current research focuses on enhancing the strain production capacity and synthesizing polymers with novel material properties. Many of the corresponding protocols for strain engineering rely on the rifampicin-resistant variant, <it>P. putida </it>KT2442. However, it remains unclear whether these two strains can be treated as equivalent in terms of mcl-PHA production, as the underlying antibiotic resistance mechanism involves a modification in the RNA polymerase and thus has ample potential for interfering with global transcription.</p> <p>Results</p> <p>To assess PHA production in <it>P. putida </it>KT2440 and KT2442, we characterized the growth and PHA accumulation on three categories of substrate: PHA-related (octanoate), PHA-unrelated (gluconate) and poor PHA substrate (citrate). The strains showed clear differences of growth rate on gluconate and citrate (reduction for KT2442 > 3-fold and > 1.5-fold, respectively) but not on octanoate. In addition, <it>P</it>. <it>putida </it>KT2442 PHA-free biomass significantly decreased after nitrogen depletion on gluconate. In an attempt to narrow down the range of possible reasons for this different behavior, the uptake of gluconate and extracellular release of the oxidized product 2-ketogluconate were measured. The results suggested that the reason has to be an inefficient transport or metabolization of 2-ketogluconate while an alteration of gluconate uptake and conversion to 2-ketogluconate could be excluded.</p> <p>Conclusions</p> <p>The study illustrates that the recruitment of a pleiotropic mutation, whose effects might reach deep into physiological regulation, effectively makes <it>P. putida </it>KT2440 and KT2442 two different strains in terms of mcl-PHA production. The differences include the onset of mcl-PHA production (nitrogen limitation) and the resulting strain performance (growth rate). It remains difficult to predict a priori<it/>where such major changes might occur, as illustrated by the comparable behavior on octanoate. Consequently, experimental data on mcl-PHA production acquired for <it>P. putida </it>KT2442 cannot always be extrapolated to KT2440 and vice versa, which potentially reduces the body of available knowledge for each of these two model strains for mcl-PHA production substantially.</p>
Trimeric autotransporter adhesins (TAAs) are multimeric surface proteins, involved in various biological traits of pathogenic Gram-negative bacteria including adherence, biofilm formation, invasion, survival within eukaryotic cells, serum resistance and cytotoxicity. TAAs have a modular architecture composed by a conserved membrane-anchored C-terminal domain and a variable number of stalk and head domains. In this study, a bioinformatic approach has been used to analyze the distribution and architecture of TAAs among Burkholderia cepacia complex (Bcc) genomes. Fifteen genomes were probed revealing a total of 74 encoding sequences. Compared with other bacterial species, the Bcc genomes contain a disproportionately large number of TAAs (two genes to up to 8 genes, such as in B.cenocepacia). Phylogenetic analysis showed that the TAAs grouped into at least eight distinct clusters. TAAs with serine-rich repeats are clearly well separated from others, thereby representing a different evolutionary lineage. Comparative gene mapping across Bcc genomes reveals that TAA genes are inserted within conserved synteny blocks. We further focused our analysis on the epidemic strain B. cenocepacia J2315 in which 7 TAAs were annotated. Among these, 3 TAA-encoding genes (BCAM019, BCAM0223 and BCAM0224) are organized into a cluster and are candidates for multifunctional virulence factors. Here we review the current insights into the functional role of BCAM0224 as a model locus.