Microbiologically influenced corrosion inhibition of carbon steel via biomineralization induced by Shewanella putrefaciens

Microbiologically influenced corrosion inhibition (MICI) of Q235 carbon steel by biomineralization was investigated via a combination of surface analysis, electrochemistry, and scanning electrochemical microscopy (SECM). The results showed that Shewanella putrefaciens used the cell walls as the nucleation sites to induce the formation of a protective biomineralized layers which contained calcite and extracellular polymeric substances on the steel surface. The potentiodynamic polarization results demonstrated that the corrosion current density (icorr value) of the biomineralized steel surface was 0.38 μA cm−2, which was less than one-tenth that of the blank steel in a sterile medium (4.86 μA cm−2) after 14 days. The biomineralized layers presented wear resistance and could self-repair after undergoing mechanical damage under microbial conditions as verified by morphological and SECM observations. This work reveals that microbial-induced carbonate biomineralization, as a MICI approach, may be considered as a reliable, low-cost, environmentally friendly corrosion inhibition strategy.

Hormonal Regulation and Crosstalk of Auxin/Cytokinin Signaling Pathways in Potatoes In Vitro and in Relation to Vegetation or Tuberization Stages

Auxins and cytokinins create versatile regulatory network controlling virtually all aspects of plant growth and development. These hormonal systems act in close contact, synergistically or antagonistically, determining plant phenotype, resistance and productivity. However, the current knowledge about molecular interactions of these systems is still scarce. Our study with potato plants aimed at deciphering potential interactions between auxin and cytokinin signaling pathways at the level of respective gene expression. Potato plants grown on sterile medium with 1.5% (vegetation) or 5% (tuberization) sucrose were treated for 1 h with auxin or cytokinin. Effects of these two hormones on expression profiles of genes belonging to main signaling pathways of auxin and cytokinin were quantified by RT-qPCR. As a result, several signaling genes were found to respond to auxin and/or cytokinin by up- or down-regulation. The observed effects were largely organ-specific and depended on sucrose content. Auxin strongly reduced cytokinin perception apparatus while reciprocal cytokinin effect was ambiguous and sucrose-dependent. In many cases, functional clustering of genes of the same family was observed. Promoters in some clusters are enriched with canonic hormone-response cis-elements supporting their direct sensitivity to hormones. Collectively, our data shed new light on the crosstalk between auxin- and cytokinin signaling pathways.

Effect of Prophylactic Vitamin C Administration On The Efficiency of Florfenicol Or Sulfadiazine-Trimethoprim Antimicrobial Therapy In Chickens With Staphylococcal Arthritis

Septic arthritis (SA) shows improper response to antibacterial therapy. This study evaluates the effect of prophylactic vitamin C administration on the efficiency of sulfadiazine-trimethoprim (SDT) or florfenicol (FF) in broilers with experimental SA. Broilers (210) were randomly allocated into 7 equal groups: I. Negative control (NC) (normal birds). II. Positive control (PC) that rendered arthritic by injection of multi drug resistant S. aureus in tibiotarsal joint at the age of 35 days. III. Vehicle control (injected with sterile medium). IV. Arthritic FF-treated (20 mg/kg/day). V. Arthritic vitamin C+FF-treated (as above+vitamin C at 15g/100L of D.W. from day 25 of age). VI. Arthritic SDT-treated (35 mg/kg/day). VII. Arthritic vitamin C+SDT-treated. Antibacterials started at day 39 of age and lasted for 5 days. Samplings were performed at the age of 44 and 54 days. A long lasting SA with severe fibrinoheterophilic synovitis and reduced body weights developed in PC broilers as compared to NC group (p<0.05). Oxidative stress was present at sampling 1. Arthritis was not reflected in IL-6 levels in synovial fluid. None of the antibacterials resulted in completely successful treatment. Vitamin C did not appreciably improve lameness and arthritis scores, although it decreased lipid peroxidation and improved weights of FF treated-arthritic birds. For SDT-treated birds, vitamin C only ameliorated histopathological changes. In conclusion, except for improving body weight in FF-treated birds, prophylactic administration of vitamin C is not associated with improvements in clinical outcome of antimicrobial therapy of broilers with SA, although it ameliorates oxidative stress and some histopathological changes.

EFFECT OF IRRADIATION IN HONEY INOCULATED WITH Bacillus sporothermodurans

Honey is a natural viscous product widely used for nutritional and medicinal purposes. Although it’s a food that presents a high degree of resistance against the growth of microorganisms is not a sterile medium. Spore-forming bacteria, such as Clostridium botulinum, are present in honey and it’s the only recorded source of food carrier of the agent that causes childhood botulism. The steps of honey processing do not include the heat treatment for its commercial sterility, due to the application of heat increase the presence of hydroxymethylfurfural. Food irradiation is a method of preservation that can be applied in the processing of honey by not physically altering the appearance, shape or temperature of the product. The objective of this work was to evaluate the effect of gamma irradiation on honey inoculated with Bacillus sporothermodurans spores. The inoculation of 106 CFU.mL-1 of lyophilized culture of this bacterium in the honey samples was carried out and the irradiation of the samples at 5, 10 and 15 kGy doses was carried out. After irradiation, the samples were incubated at 30o C for 72 h in Brain Heart Infusion (BHI) agar. The count present reduction of one logarithmic cycle in the number of colonies in the 5 kGy irradiated honeys. In the samples irradiated with doses of 10 and 15 kGy there was no microbial growth and spore germination. It’s concluded that irradiation constitutes an excellent conservation method, which can be used to guarantee the microbiological quality of the honey.

An Improved Halo Method for Evaluating the Antibacterial Activity of Leather

In order to evaluate leather antibacterial activity rapidly and accurately, an improved halo method was developed based on conventional halo method and the agar diffusion plate method. During the new method, there were two layers of medium, the bottom was sterile medium and the top was medium containing microbes; more than one leather sample could be tested in a culture dish. The antibacterial activities of leather treated by nano-silver, nano-ZnO and butyl paraben against Escherichia coli, Staphylococcus aureus, Aspergillus niger and Rhodotorula mucilaginosa were tested by the new method. The results indicated intraclass correlation coefficient values were greater than 0.7 but the P values were less than 0.05 during improved halo method testing, thus, the repeatability and reliability was comparable or even better than conventional method. Nano-silver showed excellent and broad antibacterial activity and the difference between each antibacterial agent could be observed clearly and intuitively during improved halo method testing. In sum, improved halo method was a fast, accurate, qualitative and quantitative testing method and would be a new choice for evaluating leather antibacterial activity.

Bacteria Associated with Russian Wheat Aphid (Diuraphis noxia) Enhance Aphid Virulence to Wheat

Phenotypic responses to biotic stresses are often studied as the interactions between two species; however, in the phytobiome, these responses frequently result from complex interactions involving several organisms. Here, we show that variation in chlorosis caused by Russian wheat aphid (Diuraphis noxia) feeding is determined, in part, by aphid-associated bacteria. Proteomic analysis of fluids injected into a sterile medium by the aphid during feeding indicate that 99% of the proteins are of bacterial origin. Of these, the greatest proportion are produced by bacteria in the order Enterobacteriales. Bacteria from five genera in four families that have the capacity to produce these proteins were isolated directly from aphids as well as from wheat leaves only after D. noxia feeding. By themselves or in combination, these bacteria were not virulent to wheat, even at high inoculum levels. Metagenomic analysis showed that the same five D. noxia-associated genera dominated the non-Buchnera component of the aphid microbiome, and that representation of these genera was reduced in aphids from colonies established after isolation of newborn nymphs from their mothers prior to feeding (isolated aphids). Isolation or treatment with antibiotics reduced bacterial numbers, and these aphids caused less feeding damage on wheat than non-isolated or non-antibiotic-treated aphids. Our data show that bacterial proteins are a significant component of Russian wheat aphid saliva, that the bacteria producing these proteins are associated with aphids and plants fed upon by aphids, and that these aphid-associated bacteria facilitate aphid virulence to wheat.

ECOLOGICAL FEATURES OF MICROBIOCENOSIS OF THE SKIN OF MAMMARY GLANDS AND VAGINA IN PREGNANT WOMEN WITH THREAT OF PRETERM LABOR

Background. The threat of preterm birth is one of the most topical issues in the world medicine. According to the statistics, from 12-13 to 25-35 % of all pregnancies end prematurely. One of the causes of preterm labour is chronic inflammatory processes of female genital organs and disorder of microbiocenosis. Timely diagnosis and adequate treatment will reduce the risk of premature labour and avoid perinatal loss.Objective. We examined and analysed the microflora of the skin of mammary glands and mucous membrane of vagina in healthy pregnant women and patients with threat of preterm labour.Materials and methods. The examination of the pregnant was conducted at the TRMPC “Mother and Child” in several stages. First of all, we rinsed the skin of mammary glands and smeared from mucous membrane the posterior vault of vagina with sterile swabs pre-moistened in physiological solution. After that, the tampons were placed in sterile tubes and delivered to laboratory. Sowing was carried out on Petri dishes with sterile medium: ZHSA, bloods MPA, Endo, Saburo, thioglycolic medium.Conclusions. As a result of the research we found saprophytic Gram-positive and Gram-negative microorganisms (in women with a physiological course of pregnancy). In pregnant women with preterm labour, there was the increase in the number of St. haemolyticus from 13% to 87%, appearance of representatives of pathogenic flora – St. aureus (in 20%).

The Prevalence of Esbl-Producing Strains of E.coli, Isolated from Calves with Colibacilosis - Preliminary Remarks

The animals producing food have become an increasing reservoir of extended spectrum beta-lactamase producing Enterobacteriaceae. The calves and cows are exposed to a greater quantity of antibiotics, but the data concerning the prevalence of ESBL-producing Enterobacteriaceae are not enough, in comparison with other species of animals used for human consumption, such as birds (Hordijk et al., 2013).The aim of this study was to determine the prevalence of ESBL-producing E. coli involved in some episodes of colibacilosis in calves. Faeces samples were collected from 33 calves with the age ranging between 1-2 weeks and that presented clinical signs of colibacilosis. The samples were collected in a sterile medium for the taxonomic isolation and identification of the etiological agent involved, the ESBL screening being conducted subsequently using the ESBL Agar Oxoid Brilliance chromogenic medium. The phenotypic confirmation of the ESBL-producing strains was conducted in accordance with the CLSI (2014) standard through the combined disc method. Following the tests conducted, out of the 33 strains of isolated E. coli, 9 (27, 27%) were phenotypically confirmed as being ESBL strains.The studies that were previously conducted on the dairy farms have pointed out that the young calves rapidly acquire bacterial strains resistant to antibiotics that are often ESBL strains (Hordijk et al., 2013). The prevalence obtained by us, as well as an insufficient quantity of information concerning the antimicrobial resistance on this segment of species of animals used for the human consumption, support conducting a more thorough study, as well as the identification of ESBL resistance genes, but also of the plasmids that encode the transmission of these genes.

Use of Silver Nanoparticles Reduces Internal Contamination of External Hexagon Implants by Candida albicans

Since the dental implant/abutment interface cannot totally seal the passage of microorganisms, the interior of implant becomes a reservoir of pathogenic microorganisms that produce and maintain chronic inflammation in the tissues around implants. Silver nanoparticles (nano-Ag) are potent and broad-spectrum antimicrobial agents. The aim of this study was to evaluate the capacity of the nano-Ag to prevent the contamination of the implant internal surface byCandida albicans, caused by the implant/abutment microgap infiltration. Thirty-six implants were used in this experiment. Three study groups were performed: experimental group (implants receiving an application of nano-Ag in their inner cavity before installation of the abutment); positive-control group (implants receiving sterile phosphate buffer saline application instead of nano-Ag) and negative-control group (implants receiving the application of nano-Ag in the inner cavity and immersed in a sterile medium). In the positive-control and experimental groups, the implants were immersed in a Candida albicans suspension. The abutments of all three groups were screwed with a 10 N torque. After 72 h of immersion inC. albicans suspension or sterile medium, the abutments were removed and the inner surface of the implants was sampled with absorbent paper cone for fungal detection. No C. albicans contamination was observed in the negative-control group. The positive-control group showed statistically higher values of colony forming units (CFUs) of C. albicans compared with the experimental group. In conclusion, silver nanoparticles reduced C. albicans colonization inside the implants, even with low torque screw abutment.

Immunophenotyping Versus Morphological Evaluation Of Fresh and Stabilized Cerebrospinal Fluid As Diagnostic Tool For CNS Involvement In Childhood Acute Lymphoblastic Leukemia

Introduction Presence of malignant cells in cerebrospinal fluid (CSF) is a risk factor in pediatric acute lymphoblastic leukemia (ALL). Consequently, these patients receive extra intrathecal treatment. We evaluated the concordance between morphological and flow-cytometric (FCM) results, both on freshly analyzed and on stabilized, overnight transported samples. Methods Diagnostic CSF samples of 61 newly diagnosed pediatric ALL patients were divided in two aliquots. One was sent to the local laboratory and processed within a few hours after sampling (lab1). A second aliquot was 1:1 diluted with sterile medium and sent to the reference laboratory (lab2). For all samples, a MGG (May-Grünwald-Giemsa) stained cytocentrifuged slide was morphologically evaluated and two 6-color FCM stainings were performed. Samples were considered positive (CNS2) by MGG if at least one blast was seen and by immunophenotyping if a cluster (≥ 10 events) of ALL cells was detected. Results Comparison of morphological data between both laboratories showed concordance in 33 samples (53%). In 20 of the 28 discordant samples only 1 or 2 blasts were reported by a single laboratory. Comparison of FCM data between laboratories was concordant in 58 samples (95%). Three samples (tumor load 15%-18%) were reported positive by one laboratory only; in two of these <100 cells could be acquired per tube. Comparison between FCM and morphology showed discordant results in 25 samples (41%) for lab1 and 19 (31%) in lab2. One discordant case was positive by FCM but negative by morphology, in all others only morphology was reported positive. The latter cases mostly had 1 or 2 blasts reported by morphology, generally not confirmed by the other laboratory. Conclusions This study shows that morphological analysis of CSF samples is non-reproducible if only 1 or 2 blasts are suspected. In contrast, FCM analysis of CSF is highly reproducible between fresh and stabilized samples. Although immunophenotyping still seems less sensitive than morphology, discordant samples generally have only 1 or 2 blasts reported by MGG, which is highly irreproducible. Nevertheless, by using a single 8-color tube higher cell numbers may be acquired and the FCM sensitivity may be increased. Disclosures: No relevant conflicts of interest to declare.