Colonization Levels Research Articles

Haline Tolerance of Stomatopod (Crustacea) Larvae and Pelagic Dispersal of Two Common Species in the Western Atlantic

AbstractPelagic larval stages play a critical role in the dynamics of marine populations since they are the main way of dispersal and habitat colonization. Here, we examined the larval dispersal pathways of two common stomatopod species in the western Atlantic: Squilla empusa and Lysiosquilla scabricauda. To complement this goal, we also analyzed the haline tolerance of the stomatopod larvae collected in an estuary from the southern Gulf of Mexico. Larval dispersal was simulated using a Lagrangian particle‐tracking module coupled to the Global HYCOM model and consisted of releasing 100 passive particles from each starting site. Results indicated a high level of larval retention in the west Florida shelf and over the narrow western shelf of the Gulf of Mexico. In the South Atlantic Bight, Central America, and northern South America the larval transport was almost unidirectional following the pattern of currents. Generally, connections were among nearby sites, but long‐distance transport can also occur when larvae are trapped by great high‐speed currents. Retention of larvae and connection with neighboring sites were due to local atmospheric and hydrological conditions. During fieldwork, we found two kinds of larvae: antizoea and alima. Morphological characteristics of the antizoea correspond to the superfamily Lysiosquilloidea, and those of the alima, with the superfamily Squilloidea. The antizoea larvae were found in salinity values as low as 21.9 psu, while the alima were at 23.2 psu. Salinity tolerances and dispersal potential of larvae indicate a high level of colonization of new habitats and a broad intrusion into the estuaries.

Oral Candida in post‐radiotherapy patients with xerostomia/hyposalivation: A narrative review

AbstractObjectiveHead and Neck Cancer (HNC) patients receiving radiotherapy (RT) often suffer from xerostomia and/or hyposalivation. As saliva plays an important antimicrobial and cleansing roles, these patients are at higher risks of opportunistic infections. This narrative review aims to provide an overview of current evidence on oral Candida colonisation and infection in these patients.MethodsA literature review of clinical studies on oral Candida colonisation and candidiasis in HNC patients receiving radiotherapy/chemoradiotherapy was conducted.ResultsMany clinical studies found high levels of Candida colonisation and a substantial proportion of post‐RT HNC patients suffering from oropharyngeal candidiasis (OPC). Importantly, oral Candida could be a reservoir for life‐threatening systemic infection in immunocompromised patients. The rising prevalence of non‐albicans Candida species and drug‐resistant infections has made identification of Candida species and antifungal susceptibility more important. Recent advances in oral microbiome and its interactions with Candida are discussed. This review also offers perspectives on limitations of current evidence and suggestions for future research.ConclusionFurther research to better understand Candida carriage, microbiome, OPC, and xerostomia/hyposalivation post‐RT would aid in devising a more comprehensive long‐term management plan and novel therapeutic approaches for HNC patients to achieve the full benefits of RT while minimising side effects.

Comparative transcriptome reveals importance of export apparatus subunit (ascR) in type III secretion system and its roles on biological properties, gene expression profiles, virulence and colonization of Aeromonas veronii

Aeromonas veronii, an opportunistic pathogen, is known to cause serious infections across various species. In our previous study, we discovered that A. veronii GL2 exhibited a virulence up to ten times greater than that of FO1. To ascertain the factors contributing to the disparity in virulence between the two strains, we conducted a comparative transcriptome analysis. This analysis reveals a significant upregulation (P < 0.05) of the ascR gene in GL2 compared with FO1. Additionally, six differentially expressed genes (DEGs) were identified within the “Bacterial secretion system” pathway (map03070), with ascR being an essential component of type III secretion system (T3SS). AscR, considered as SctR family export apparatus subunit within the T3SS, has ambiguous roles in the biological properties, gene expression profiles, virulence and colonization of A. veronii. Therefore, we constructed a mutant strain (ΔascR) by homologous recombination. Comparative analysis with the wide-type GL2 reveals no significant differences in terms of colony morphology, growth curve, hemolytic activity and protease activity. However, significant reductions (P < 0.01) were observed in the abilities of biofilm formation and swimming mobility. No remarkable difference was noted in the lengths of flagella. The LD50 value of ΔascR was to be 5.15 times higher than that of GL2. Interestingly, the mRNA expression of ascC, ascD, ascJ and ascI genes in the T3SS, and mshB, mshE, mshK and mshP genes in the MSHA type pili were significantly upregulated (P < 0.05) in ΔascR, potentially due to transcriptional compensation. Further analysis of enzymatic biomarkers revealed that ΔascR might not destruct the recognition of innate immune response in host remarkably, but the colonization levels of A.veronii were significantly suppressed (P < 0.01) in ΔascR group. In conclusion, the ascR gene may be a key determinant in regulating the virulence of A. veronii, and the destruction of the T3SS caused by ascR deficiency results in these notable changes.

Weather ageing effects on the long-term thermal conductivity and biological colonisation of thermal insulating mortars with EPS, cork and aerogel

The use of thermal insulation materials in the opaque walls is one of the best strategies toward the improvement of the thermal performance of the building envelope, thereby contributing to increase the energy efficiency of the built environment. In this context, an increasing number of studies are focusing on the development of mortars with enhanced thermal performance, i.e., thermal insulating mortars. However, considering the innovative character of these materials, reliable data on their long-term performance is still lacking, particularly concerning the thermal performance and suitability to refurbishment works. The aim of this paper is to evaluate the long-term thermal conductivity and biological colonisation of industrially produced and experimentally designed thermal mortars with EPS, cork and silica aerogel aggregates. The long-term performance of the mortars was assessed prior, during and after exposure to three accelerated ageing tests including elevated temperature, freeze–thaw cycles and high humidity levels. For each test, an empirical model (i.e., Arrhenius law, Peck model, and Coffin-Manson equation) was used to compute the acceleration factor, thus allowing to correlate the accelerated and natural ageing results and to estimate the degradation levels that would be obtained after 10 years of exposure to natural weather conditions. The results of the thermal conductivity show that a maximum increase of 10 % and 30 % can be obtained after ageing for the industrially produced and experimentally designed mortars, respectively. Moreover, all mortars were susceptible to mould growth, with the greatest biological colonisation levels obtained after the high moisture content ageing for the experimentally designed mortars.

The Growth-Promoting and Colonization of the Pine Endophytic Pseudomonas abietaniphila for Pine Wilt Disease Control.

In this study, we focused on evaluating the impact of Pseudomonas abietaniphila BHJ04 on the growth of Pinus massoniana seedlings and its biocontrol efficacy against pine wilt disease (PWD). Additionally, the colonization dynamics of P. abietaniphila BHJ04 on P. massoniana were examined. The growth promotion experiment showed that P. abietaniphila BHJ04 significantly promoted the growth of the branches and roots of P. massoniana. Pot control experiments indicated that strain BHJ04 significantly inhibited the spread of PWD. There were significant changes in the expression of several genes related to pine wood nematode defense in P. massoniana, including chitinase, nicotinamide synthetase, and triangular tetrapeptide-like superfamily protein isoform 9. Furthermore, our results revealed significant upregulation of genes associated with the water stress response (dehydration-responsive proteins), genetic material replication (DNA/RNA polymerase superfamily proteins), cell wall hydrolase, and detoxification (cytochrome P450 and cytochrome P450 monooxygenase superfamily genes) in the self-regulation of P. massoniana. Colonization experiments demonstrated that strain BHJ04 can colonize the roots, shoots, and leaves of P. massoniana, and the colonization amount on the leaves was the greatest, reaching 160,000 on the 15th day. However, colonization of the stems lasted longer, with the highest level of colonization observed after 45 d. This study provides a preliminary exploration of the growth-promoting and disease-preventing mechanisms of P. abietaniphila BHJ04 and its ability to colonize pines, thus providing a new biocontrol microbial resource for the biological control of plant diseases.

The phosphate starvation response regulator PHR2 antagonizes arbuscule maintenance in Medicago.

Phosphate starvation response (PHR) transcription factors play essential roles in regulating phosphate uptake in plants through binding to the P1BS cis-element in the promoter of phosphate starvation response genes. Recently, PHRs were also shown to positively regulate arbuscular mycorrhizal colonization in rice and lotus by controlling the expression of many symbiotic genes. However, their role in arbuscule development has remained unclear. In Medicago, we previously showed that arbuscule degradation is controlled by two SPX proteins that are highly expressed in arbuscule-containing cells. Since SPX proteins bind to PHRs and repress their activity in a phosphate-dependent manner, we investigated whether arbuscule maintenance is also regulated by PHR. Here, we show that PHR2 is a major regulator of the phosphate starvation response in Medicago. Knockout of phr2 showed reduced phosphate starvation response, symbiotic gene expression, and fungal colonization levels. However, the arbuscules that formed showed less degradation, suggesting a negative role for PHR2 in arbuscule maintenance. This was supported by the observation that overexpression of PHR2 led to enhanced degradation of arbuscules. Although many arbuscule-induced genes contain P1BS elements in their promoters, we found that the P1BS cis-elements in the promoter of the symbiotic phosphate transporter PT4 are not required for arbuscule-containing cell expression. Since both PHR2 and SPX1/3 negatively affect arbuscule maintenance, our results indicate that they control arbuscule maintenance partly via different mechanisms. While PHR2 potentiates symbiotic gene expression and colonization, its activity in arbuscule-containing cells needs to be tightly controlled to maintain a successful symbiosis in Medicago.

Hymenoscyphus fraxineus persistence in the ash litter

AbstractHymenoscyphus fraxineus causes ash dieback in Europe. It overwinters on ash leaf residue (rachis) within the forest litter. In late spring, the fungus produces apothecia on the rachises and releases ascospores to infect leaves. Previous studies reported that H. fraxineus was able to produce apothecia on the rachis for 5 years after the leaf infection under artificial conditions. However, ash litter is known to decompose rapidly in situ. We therefore monitored the decomposition kinetics of ash leaf debris and the persistence of the pathogen, as well as its ability to produce apothecia in the forest litter. For this, leaves shed in autumn in stands affected by ash dieback were placed in mesh bags and left in the forest litter for 6, 18 and 30 months. At each sampling period, litter mass loss and level of colonization of the rachises by H. fraxineus were measured, as was the pathogen's ability to produce apothecia on them. Despite high fragmentation, about 14% of the rachis dry weight remained in the mesh bags after 30 months, and the pathogen retained the ability to produce apothecia on these rachises. A simulation estimating the age composition of the colonized rachises present in the litter during the fruiting period was developed from these results. It shows that the persistence of H. fraxineus in old rachises of the litter represents a reservoir of inoculum that could compensate for poor colonization of autumn leaves and revive local outbreaks after years of unfavourable weather for the development of the pathogen.

Risk factors for asymptomatic bacterial colonization of cardiac implantable electronic devices

Abstract Introduction With broadening indications and a progressively ageing demographic, incidence of cardiac electronic implantable device (CIED) implantation increased. Despite device infection being rare, it persists as a serious complication concomitant with a high mortality rate. While extensive research on cardiac device infection (CDI) has been conducted, the incidence and clinical significance of asymptomatic bacterial CIED colonisation has not been investigated so far. Purpose Our study aims to elucidate potential risk factors for and investigate the clinical significance of asymptomatic bacterial CIED colonisation. Methods and Results In this prospective single centre study, 345 patients with no clinical signs of CIED infection underwent a generator exchange. In total, 78 pacemakers (PM), 97 implantable cardiac defibrillators (ICD), 67 cardiac resynchronisation therapy devices (CRT), 1 baroreceptor stimulator, as well as 102 implantable loop recorders were sonicated to determine the presence of adherent microorganisms (biofilms). Intraoperative swabs were collected in 329 patients. For statistical analysis, detection of ≥1 colony forming units (CFU) during sonication was considered a significant level of bacterial colonisation. The ≥50 CFU threshold was established in order to examine risk factors relevant for higher levels of bacterial colonization. 88 CIED (25.5%) showed bacterial colonisation ≥1 CFU while 44 CIED (12.8%) were colonised with ≥50 CFU. Multivariate analysis revealed male gender as independent risk factor for both ≥1 CFU (p&amp;lt;0.001; OR 7.73, CI 2.84-21.04) and ≥50 CFU (p&amp;lt;0.001; OR 12.14, CI 2.79-52.78). and immunosuppressive medication (p=0.018; OR 3.31; CI 1.23-8.92) as independent risk factor identified for ≥50 CFU colonisation. For both cutoffs, Cutibacterium acnes emerged as the most frequently detected bacterium during sonication, followed by coagulase negative Staphylococci (CoNS) with Staphylococcus epidermidis being the most common within this CoNS group. During the follow-up (384.5 +/- 480.6 days), 287 patients showed absence of CDI (53 patients lost to follow-up). Of the five patients with CDI, one exhibited concordant results between sonication, swab, and blood culture for Cutibacterium acnes, one presented with partially concordant results, whereas the other three showed varying degrees of disconcordance between index event microbiological results and subsequent CDI pathogens. Conclusion Remarkably, 27.2% of CIEDs with leads (PM, ICD, CRT) exhibited bacterial colonisation. Out of the 5 CDIs identified, 4 were associated with positive sonication results. In addition, our study identifies male gender and immunosuppressive medication as significant risk factors for asymptomatic bacterial CIED colonisation. Thus, in patients with these given risk factors, CIED sonication should be considered for risk stratification with regard to a subsequent CIED infection and possible targeted antimicrobial therapy.Flow Chart

Efficiently recording and processing data from arbuscular mycorrhizal colonization assays using AMScorer and AMReader.

Arbuscular mycorrhizal (AM) fungi engage with land plants in a widespread, mutualistic endosymbiosis which provides their hosts with increased access to nutrients and enhanced biotic and abiotic stress resistance. The potential for reducing fertiliser use and improving crop resilience has resulted in rapidly increasing scientific interest. Microscopic quantification of the level of AM colonization is of fundamental importance to this research, however the methods for recording and processing these data are time-consuming and tedious. In order to streamline these processes, we have developed AMScorer, an easy-to-use Excel spreadsheet, which enables the user to record data rapidly during from microscopy-based assays, and instantly performs the subsequent data processing steps. In our hands, AMScorer has more than halved the time required for data collection compared to paper-based methods. Subsequently, we developed AMReader, a user-friendly R package, which enables easy visualization and statistical analyses of data from AMScorer. These tools require only limited skills in Excel and R, and can accelerate research into AM symbioses, help researchers with variable resources to conduct research, and facilitate the storage and sharing of data from AM colonization assays. They are available for download at https://github.com/EJarrattBarnham/AMReader, along with an extensive user manual.

Impaired upper respiratory tract barrier function during postnatal development predisposes to invasive pneumococcal disease.

Infants are highly susceptible to invasive respiratory and gastrointestinal infections. To elucidate the age-dependent mechanism(s) that drive bacterial spread from the mucosa, we developed an infant mouse model using the prevalent pediatric respiratory pathogen, Streptococcus pneumoniae (Spn). Despite similar upper respiratory tract (URT) colonization levels, the survival rate of Spn-infected infant mice was significantly decreased compared to adults and corresponded with Spn dissemination to the bloodstream. An increased rate of pneumococcal bacteremia in early life beyond the newborn period was attributed to increased bacterial translocation across the URT barrier. Bacterial dissemination in infant mice was independent of URT monocyte or neutrophil infiltration, phagocyte-derived ROS or RNS, inflammation mediated by toll-like receptor 2 or interleukin 1 receptor signaling, or the pore-forming toxin pneumolysin. Using molecular barcoding of Spn, we found that only a minority of bacterial clones in the nasopharynx disseminated to the blood in infant mice, indicating the absence of robust URT barrier breakdown. Rather, transcriptional profiling of the URT epithelium revealed a failure of infant mice to upregulate genes involved in the tight junction pathway. Expression of many such genes was also decreased in early life in humans. Infant mice also showed increased URT barrier permeability and delayed mucociliary clearance during the first two weeks of life, which corresponded with tighter attachment of bacteria to the respiratory epithelium. Together, these results demonstrate a window of vulnerability during postnatal development when altered mucosal barrier function facilitates bacterial dissemination.

Isolasi Dan Identifikasi Bakteri Escherichia coli, Klebsiella sp., Dan Staphylococcus aureus Pada Ambing dan Susu Kambing Peranakan Etawa

A disease that is usually found in etawa crossbreed goats is mastitis. Mastitis can be caused by Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus bacteria. This study aims to isolate and identify Escherichia coli, Klebsiella sp, and Staphylococcus aureus bacteria found in the mammary of etawa crossbreed goats and determine the level of bacterial colonization of Escherichia coli, Klebsiella Sp., and Staphylococcus aureus in the milk of etawa crossbreed goats calculated using the Total Plate Count (TPC) test. The samples used in this study were mammary swabs and milk from 6 PE goats. Isolation and identification of bacteria in the mammary were carried out by planting samples on differential and selective media, Gram staining, and biochemical tests. Calculation of bacterial colonies in PE goat milk used by TPC test. The results of this study indicated that Escherichia coli and Staphylococcus aureus were successfully isolated and identified from 6 PE goat mammary, but Klebsiella sp was only found in 1 PE goat mammary. The TPC value of PE goat milk obtained an average of 2.9x105 and it’s still below the maximum SNI standard for fresh milk, but exceeds the Thai Agricultural Standard for fresh goat's milk, its 2x105 CFU/ml.

Possible link between colonization of the gastrointestinal tract by Citrobacter rodentium in C57BL/6 mice and microbiota composition.

Colonization resistance, conferred by the host's microbiota through both direct and indirect protective actions, serves to protect the host from enteric infections. Here, we identified the specific members of the gut microbiota that impact gastrointestinal colonization by Citrobacter rodentium, a murine pathogen causing colonic crypt hyperplasia. The gut colonization levels of C. rodentium in C57BL/6 mice varied among breeding facilities, probably due to differences in microbiota composition. A comprehensive analysis of the microbiota revealed that specific members of the microbiota may influence gut colonization by C. rodentium, thus providing a potential link between the two.

Efficacy of Alum-Adjuvanted Peptide and Carbohydrate Conjugate Vaccine Candidates against Group A Streptococcus Pharyngeal Infection in a Non-Human Primate Model.

Vaccine development against group A Streptococcus (GAS) has gained traction in the last decade, fuelled by recognition of the significant worldwide burden of the disease. Several vaccine candidates are currently being evaluated in preclinical and early clinical studies. Here, we investigate two conjugate vaccine candidates that have shown promise in mouse models of infection. Two antigens, the J8 peptide from the conserved C-terminal end of the M protein, and the group A carbohydrate lacking N-acetylglucosamine side chain (ΔGAC) were each conjugated to arginine deiminase (ADI), an anchorless surface protein from GAS. Both conjugate vaccine candidates combined with alum adjuvant were tested in a non-human primate (NHP) model of pharyngeal infection. High antibody titres were detected against J8 and ADI antigens, while high background antibody titres in NHP sera hindered accurate quantification of ΔGAC-specific antibodies. The severity of pharyngitis and tonsillitis signs, as well as the level of GAS colonisation, showed no significant differences in NHPs immunised with either conjugate vaccine candidate compared to NHPs in the negative control group.

Impacts of Arbuscular Mycorrhizal Fungi on Metabolites of an Invasive Weed Wedelia trilobata.

The invasive plant Wedelia trilobata benefits in various aspects, such as nutrient absorption and environmental adaptability, by establishing a close symbiotic relationship with arbuscular mycorrhizal fungi (AMF). However, our understanding of whether AMF can benefit W. trilobata by influencing its metabolic profile remains limited. In this study, Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was conducted to analyze the metabolites of W. trilobata under AMF inoculation. Metabolomic analysis identified 119 differentially expressed metabolites (DEMs) between the groups inoculated with AMF and those not inoculated with AMF. Compared to plants with no AMF inoculation, plants inoculated with AMF showed upregulation in the relative expression of 69 metabolites and downregulation in the relative expression of 50 metabolites. AMF significantly increased levels of various primary and secondary metabolites in plants, including amino acids, organic acids, plant hormones, flavonoids, and others, with amino acids being the most abundant among the identified substances. The identified DEMs mapped 53 metabolic pathways, with 7 pathways strongly influenced by AMF, particularly the phenylalanine metabolism pathway. Moreover, we also observed a high colonization level of AMF in the roots of W. trilobata, significantly promoting the shoot growth of this plant. These changes in metabolites and metabolic pathways significantly affect multiple physiological and biochemical processes in plants, such as free radical scavenging, osmotic regulation, cell structure stability, and material synthesis. In summary, AMF reprogrammed the metabolic pathways of W. trilobata, leading to changes in both primary and secondary metabolomes, thereby benefiting the growth of W. trilobata and enhancing its ability to respond to various biotic and abiotic stressors. These findings elucidate the molecular regulatory role of AMF in the invasive plant W. trilobata and provide new insights into the study of its competitive and stress resistance mechanisms.

MICROBIOLOGICAL CHARACTERISTICS OF THE EFFECTIVENESS OF THE TREATMENT OF RATS WITH AN EXPERIMENTAL INFECTED WOUND USING AN ANTISEPTIC AND AN IMMUNOMODULATOR

Despite the outstanding achievements in treating wounds, the question of the development and search of new medicines and new medicinal antimicrobial compositions, which would provide an opportunity to improve the treatment of infected and purulent wounds in modern conditions, is still relevant.Material and methods. On the basis of the Department of Microbiology and the veterinary medical clinic of National Pyrogov Memorial Medical University (Vinnytsya, Ukraine), an experimental study was conducted, which consisted of the microbiological evaluation of the use of the immunomodulator "Blastomunil" in the treatment of infected wounds in rats. Under anesthesia, a wound of 1.5x1.5 cm was made in the interscapular area of the animals. It was infected, and then it was treated by intramuscular injection of Blastomunyl, or its local application as monotherapy or in combination with Decamethoxine. The collection of material from the wounds for microbiological research was carried out for 3, 7, 10 and 14 days, followed by a microbiological study of the quantitative content of microorganisms in the wound and their species identification. Numerical values of the number of microorganisms in wounds were expressed as the decimal logarithm of colony-forming units per ml (lg CFU/ml).Research results. Indicators of S.aureus wound contamination on the third day decreased from the 3rd to the 6th group by 1.35, 1.32, 1.46, 1.49, 1.26. and 1.29 times, respectively, with the most significant indicators in 5 (3.74±0.14 lg CFU/ml) and 6 (2.48±0.45 lg CFU/ml) groups, which were significantly different from the control (p&lt;0.05). Regarding P.aeruginosa, a significant logarithmic decrease in microbial contamination was observed in groups 3 (3.78±0.26 lg CFU/ml), 5 (3.12±0.17 lg CFU/ml), 6 (2.48±0.45 lg CFU/ml), and the reduction was respectively, 1.37, 1.66 and 2.09 times, and for the 6th group was reliably the most significant (p&lt;0.05). On the 7th day, a decrease in the number of S.aureus and P.aeruginosa CFU was observed in all groups compared to the control. The most significant decrease in the level of microbial colonization of S.aureus wounds was found in group 5 (2.96±0.08 lg CFU/ml), and its multiplicity was 1.99 times, respectively, compared to the control (p&lt;0.05). A significant reduction in the colonization of wounds by the opportunistic gram-negative bacillus P.aeruginosa was established on the 7th day in groups 5 (2.32±0.36 lg CFU/ml) and 6 (1.43±0.65 lg CFU/ml), the multiplicity of logarithmic reduction of contamination was significant and reliable ( p&lt;0.05) and was 2.0 and 3.26, respectively. On the 10th day, the load of S.aureus in wounds in groups 3-6 significantly decreased. Multiplicity compared to the control was determined in 1.4, 1.54, 2.24, 2.2 times, respectively, with the best result in 5 (2.06±0.04 lg CFU/ml) and 6 (1.9±0.52 lg CFU/ml) groups. For P.aeruginosa, a reliable logarithmic decrease in microbial colonization was determined for groups 2-6, and the multiplicity compared to the control was 1.46, 1.38, 1.91, 1.86, 1.38 times with the best indicators in groups 5 (1.85±0.66 lg CFU/ml) and 6 (1.9±0.52 lg CFU/ml) (p&lt;0.05). On the 14th day, complete eradication of S.aureus and P.aeruginosa was established in wounds of groups 3-6. In the second group, the level of contamination still remained at an insignificant level and was 1.55±0.49 lg CFU/ml S.aureus and 1.04±0.2 lg CFU/ml P.aeruginosa, which is 4.2 and 5 times less than in the control group.Conclusion. Blastomunyl indirectly, apparently due to its immunomodulatory effect, exhibits significant antimicrobial properties, both when administered intramuscularly and when used locally as monotherapy or in combination with Decasan.

ARBUSCULAR MYCORRHIZAL SYMBIOSIS OF VIOLA BAOSHANENSIS AT BAOSHAN PB/ZN MINE IN CHINA

Despite great potential for arbuscular mycorrhizal fungi (AMF) in restoration of heavy metals (HMs) polluted lands, limited information is available about the arbuscular mycorrhizal (AM) symbiosis of naturally-occurring hyperaccumulators. A preliminary survey was conducted to investigate the AM symbiosis of Viola baoshanensis, a Cadmium (Cd) hyperaccumulator, growing at an abandoned mine. Shoot/root ratios of 1.78 for Cd, and 2.57 for zinc (Zn) indicate that these two metals were preferentially transported from roots to shoots, whereas the ratio of 0.32 for lead (Pb) shows that most Pb was stored in roots. High level of colonization was found in the roots of V. baoshanensis with relative mycorrhizal root length of 69.1%, relative arbuscular richness of 46.9% and relative vesicular richness of 1.7%. Fifteen AMF species were identified from the root zone soil of V. baoshanensis. The dominant AMF genus was Glomus, and the most abundant species were Glomus ambisporum and Claroideglomus etunicatum.

Polystyrene microplastics promote intestinal colonization of Aeromonas veronii through inducing intestinal microbiota dysbiosis

The premise that pathogen colonized microplastics (MPs) can promote the spread of pathogens has been widely recognized, however, their role in the colonization of pathogens in a host intestine has not been fully elucidated. Here, we investigated the effect of polystyrene MPs (PS-MPs) on the colonization levels of Aeromonas veronii, a typical aquatic pathogen, in the loach (Misgurnus anguillicaudatus) intestine. Multiple types of MPs were observed to promote the intestinal colonization of A. veronii, among which PS-MPs exhibited the most significant stimulating effect (67.18% increase in A. veronii colonization). PS-MPs inflicted serious damage to the intestinal tracts of loaches and induced intestinal microbiota dysbiosis. The abundance of certain intestinal bacteria with resistance against A. veronii colonization decreased, with Lactococcus sp. showing the strongest colonization resistance (73.64% decline in A. veronii colonization). Fecal microbiota transplantation was performed, which revealed that PS-MPs induced intestinal microbiota dysbiosis was responsible for the increased colonization of A. veronii in the intestine. It was determined that PS-MPs reshaped the intestinal microbiota community to attenuate the colonization resistance against A. veronii colonization, resulting in an elevated intestinal colonization levels of A. veronii.

Divergent colonization traits, convergent benefits: different species of arbuscular mycorrhizal fungi alleviate Meloidogyne incognita damage in tomato

Arbuscular mycorrhizal fungi (AMF) can increase plant tolerance and/or resistance to pests such as the root-knot nematode Meloidogyne incognita. However, the ameliorative effects may depend on AMF species. The aim of this work was therefore to evaluate whether four AMF species differentially affect plant performance in response to M. incognita infection. Tomato plants grown in greenhouse conditions were inoculated with four different AMF isolates (Claroideoglomus claroideum, Funneliformis mosseae, Gigaspora margarita, and Rhizophagus intraradices) and infected with 100 second stage juveniles of M. incognita at two different times: simultaneously or 2 weeks after the inoculation with AMF. After 60 days, the number of galls, egg masses, and reproduction factor of the nematodes were assessed along with plant biomass, phosphorus (P), and nitrogen concentrations in roots and shoots and root colonization by AMF. Only the simultaneous nematode inoculation without AMF caused a large reduction in plant shoot biomass, while all AMF species were able to ameliorate this effect and improve plant P uptake. The AMF isolates responded differently to the interaction with nematodes, either increasing the frequency of vesicles (C. claroideum) or reducing the number of arbuscules (F. mosseae and Gi. margarita). AMF inoculation did not decrease galls; however, it reduced the number of egg masses per gall in nematode simultaneous inoculation, except for C. claroideum. This work shows the importance of biotic stress alleviation associated with an improvement in P uptake and mediated by four different AMF species, irrespective of their fungal root colonization levels and specific interactions with the parasite.

Bacillus subtilis NBRI-W9 simultaneously activates SAR and ISR against Fusarium chlamydosporum NBRI-FOL7 to increase wilt resistance in tomato.

The study aimed to determine the pathogenicity of Fusarium species currently prevalent in tomato fields having history of chemical fungicide applications and determine the bio-efficacy of Bacillus subtilis NBRI-W9 as a potent biological control agent. Fusarium was isolated from surface-sterilized infected tomato plants collected from fields. Pathogenicity of 30 Fusarium isolates was determined by in vitro and in vivo assays. Following Koch's postulates, F. chlamydosporum (FOL7) was identified as a virulent pathogen. The biological control of FOL 7 by B. subtilis NBRI-W9 (W9) and the colonization potential of W9 were established using spontaneous rifampicin-resistant mutants. W9 showed 82% inhibition of FOL7 on a dual-culture plate and colonization levels in tomato plants of ∼5.5, ∼3.3, and ∼2.2 log10 CFU/g in root, stem, and leaf tissue, respectively. Antagonistic activity was shown by scanning electron microscopy (SEM) and cell-wall-degradative enzymes. W9 reduced FOL7 infection in net-house and field experiments by 60% and 41%, respectively. Biochemical investigation, defence enzymes, defence gene expression analysis, SEM, and field studies provide evidence of hyperparasitism and induced resistance as the mode of biological control. The study also demonstrates that the potent biocontrol agent W9, isolated from Piper, can colonize tomato plants, control fungal disease by inducing induced systemic resistance (ISR) and systemic acquired resistance (SAR) simultaneously, and increase crop yield by 21.58% under field conditions. This study concludes that F. chlamydosporum (NBRI-FOL7) is a potent, fungicide-resistant pathogen causing wilt in tomatoes. NBRI-W9 controlled FOL7 through mycoparasitism and simultaneously activated ISR and SAR in plants, providing an attractive tool for disease control that acts at multiple levels.

Bacterial Colonization of Students’ Bath Towels in a Tertiary Educational Centre in Owo, Nigeria

Bath towels are designed to assimilate profuse amount of moisture and in the process may also absorb microorganisms that are present. These microorganisms remain viable and multiply within the moist towel to become vehicles for the transmission of infectious agents especially through contaminated hands to food, household items and the surrounding environment. The study was intended to know the level of bacterial colonization of bath towels of students in a tertiary educational institution in Owo, Ondo State. Students’ bath towels were swabbed with cotton wool-tipped swab sticks and teased into 5 mL sterile 0.85% sodium chloride. This was diluted ten-folds serially: 10-1 , 10-2 , 10-3 ... 10-10, and 0.1 mL each was inoculated onto standard bacteriological media. The cultures were incubated at 37oC overnight before reading. Bacterial counts increased significantly (p&lt;0.05) from 3.4 x 104 in first week of laundry to 2.9 x 108 in towels laundered after three weeks of use. Staphylococcus aureus (74.3%) was the predominant isolate. Escherichia coli (20.2%) was the next frequently recovered microorganism. Other isolates were Klebsiella species (3.7%) and Pseudomonas aeruginosa (1.8%) was the least recovered organism. The isolates were most susceptible to pefloxacin, except Pseudomonas aeruginosa that had better susceptibility to gentamycin. The high level of bacterial colonization of bath towels with some of the regular microorganisms implicated in most human diseases brings to fore the urgent need for education on the basics of the bath towel hygiene. Keywords: Bath towels, colonization, contamination, hands, infection