Absence Of Microorganisms Research Articles

Prevalence urinary tract infections in newborns of Baghdad hospital

In the neonatal period, urinary tract infection sepsis and urinary system It is an important clinical problem because it can be associated with congenital anomalies. The aim was determine the prevalence of UTI and the causative agent in neonates with their antibiotics sensitivity patterns. This study was planned as cross-sectional study. urinary tract at a 4-year time interval in a primary neonatal unit. It was performed on newborns who were hospitalized with the diagnosis of infection. patient data It was obtained retrospectively from patient files. Prior hospitalization, urinary catheterization, premature birth and urinary Newborns with multipathogen growth in their culture were not included in the study. for study Consent was obtained from the local ethics committee. Urinary tract infection, urine sample taken by bladder catheterization 10000-50000 CFU/ml colony count or pyuria in the presence of pyuria in the culture Colony count of ≥50000 CFU/ml in the absence of microorganism was defined as growth. Gender of the patients, weeks of gestation, mode of delivery, birth weight, urinary tract postnatal days of diagnosis of infection. The difference and relationships between the obtained data were statistically evaluated. In the present study, 186 urine specimens from neonates with UTI, 110(59.13%) were positive for bacterial culture. In addition 100 specimens from healthy neonates (control) included in the present study, only 8 (8%) were positive for bacterial culture The study showed that, E. coli were the most isolated bacteria According to the distribution of the isolated bacteria among the study groups, K. pneumoniae is the second, S. aureus and P. mirabilis the least isolated bacteria from neonates, The study showed that majority of neonates with UTI were females (65.45%) and 34.55% were males, The study demonstrated that, most cases suffered from dysuria due to UTI and 27.27% suffered from fever, The research indicated that, S. aureus showed high rate of sensitivity to ciprofloxacin and oxacillin (88.23%) and resistant to ampicillin and lincomycin. S. saprophyticus showed were sensitive to cephalothin, ciprofloxacin, oxacillin and lincomycin and complete resistant to ampicillin, erythromycin and amikacin. Streptococcus faecalis showed 100% sensitivity to oxacillin while it was resistant to ciprofloxacin, ampicillin, erythromycin and amikacin. E. coli isoaltes were 53 sensitive to to ceftazidim and resistant to oxacillin and lincomycin . K. pneumoniae were sensitive to amoxiclave and resistant to ampicillin, tetracycline, erythromycin, oxacillin and lincomycin. Proteus mirabilis was sensitive to cefotaxim and it was resistant to erythromycin, ampicillin, oxacillin and lincomycin. Proteus vulgaris showed high sensitivity rate to nirtrofurontoin, cefotaxim (92.85%) and low rate of sensitivity to erythromycin (Figure 4.8). Pseudomonas aeroginosae showed high sensitivity rate to cefotaxim (86.66% ) and low rate of sensitivity (20%) to ampicillin.

Role of Rhizospheric Microbiota as a Bioremediation Tool for the Protection of Soil-Plant Systems from Microcystins Phytotoxicity and Mitigating Toxin-Related Health Risk.

Frequent toxic cyanoblooms in eutrophic freshwaters produce various cyanotoxins such as the monocyclic heptapeptides microcystins (MCs), known as deleterious compounds to plant growth and human health. Recently, MCs are a recurrent worldwide sanitary problem in irrigation waters and farmland soils due to their transfer and accumulation in the edible tissues of vegetable produce. In such cases, studies about the persistence and removal of MCs in soil are scarce and not fully investigated. In this study, we carried out a greenhouse trial on two crop species: faba bean (Vicia faba var. Alfia 321) and common wheat (Triticum aestivum var. Achtar) that were grown in sterile (microorganism-free soil) and non-sterile (microorganism-rich soil) soils and subjected to MC-induced stress at 100 µg equivalent MC-LR L−1. The experimentation aimed to assess the prominent role of native rhizospheric microbiota in mitigating the phytotoxic impact of MCs on plant growth and reducing their accumulation in both soils and plant tissues. Moreover, we attempted to evaluate the health risk related to the consumption of MC-polluted plants for humans and cattle by determining the estimated daily intake (EDI) and health risk quotient (RQ) of MCs in these plants. Biodegradation was liable to be the main removal pathway of the toxin in the soil; and therefore, bulk soil (unplanted soil), as well as rhizospheric soil (planted soil), were used in this experiment to evaluate the accumulation of MCs in the presence and absence of microorganisms (sterile and non-sterile soils). The data obtained in this study showed that MCs had no significant effects on growth indicators of faba bean and common wheat plants in non-sterile soil as compared to the control group. In contrast, plants grown in sterile soil showed a significant decrease in growth parameters as compared to the control. These results suggest that MCs were highly bioavailable to the plants, resulting in severe growth impairments in the absence of native rhizospheric microbiota. Likewise, MCs were more accumulated in sterile soil and more bioconcentrated in root and shoot tissues of plants grown within when compared to non-sterile soil. Thereby, the EDI of MCs in plants grown in sterile soil was more beyond the tolerable daily intake recommended for both humans and cattle. The risk level was more pronounced in plants from the sterile soil than those from the non-sterile one. These findings suggest that microbial activity, eventually MC-biodegradation, is a crucial bioremediation tool to remove and prevent MCs from entering the agricultural food chain.

Advanced hybrid electro-oxidation & O3 technology for water reuse in the fruit and vegetable process industry.

Alternative sanitising agents are required in the fruit and vegetable processing industry, capable of effectively disinfecting both the product and the washing water to increase its reuse, while not producing harmful by-products like chlorine-based agents. In the present work, electro-oxidation (EO) and ozone are proposed for vegetable process water reuse, being optimised for their individual and combined application. The application of hybrid electro-oxidation and ozone achieved 7 log reduction after 15 min of treatment in batch using boron-doped diamond (BDD) as anode material, showing important synergistic effects when compared with the individual treatments. When the process was applied in continuous mode, up to 6 log reduction of total bacteria was achieved using EO alone with Ru as the anode and stainless steel as the cathode, under 11 mA/cm2 of current density, a cell retention time of 12 s and no addition of chemical reagents (electrolyte). Under these conditions, the absence of microorganisms in water was maintained for more than 24 h, no harmful by-products (chlorate, bromate) were detected and no damage to lettuce seeds were observed when evaluating water reuse potential.

Bioleaching of Gold from Silicate Ore by Macrococcus caseolyticus and Acinetobacter calcoaceticus: Effect of Medium, Amino Acids and Growth Supernatant

The aims of this work were to study the gold leaching by the isolated bacteria from silicate ore. Three strains were isolated and identified as Macrococcus caseolyticus, Acinetobacter calcoaceticus, and Bacillus sp. MBEA40. However, only M. caseolyticus and A. calcoaceticus were capable of gold bioleaching. In order to examine only the effect of microorganisms involved in the gold bioleaching process, minimal medium and ethanol mineral salt medium without amino acids were used for culturing M. caseolyticus and A. calcoaceticus, respectively. The result showed that the growth supernatant (in the absence of microorganisms) of both strains might be more suitable to leaching gold from ore than leaching by microorganisms (in the presence of microorganisms) directly. This might be due to the fact that there is no interference of gold absorption and metal toxicity in microorganisms in the long-term operation. The result also confirmed that amino acids/peptides/proteins produced by microorganisms might be involved in gold bioleaching, as shown in the high-performance liquid chromatography (HPLC) results. The Fourier transform infrared spectroscopy (FTIR) study also found that amine groups and carboxylic groups played important roles in gold bioleaching by M. caseolyticus and A. calcoaceticus. In addition, the bioleaching process had significantly higher gold leaching than mixed pure amino acids due to the growth supernatant containing mixed amino acids/peptides/proteins and other compounds. Therefore, the growth supernatant of M. caseolyticus and A. calcoaceticus can be applied in gold bioleaching under neutral pH conditions, which is considered to be a safe, not corrosive, and environmentally friendly leaching process. This study is also needed further study in order to increase the percentage of gold bioleaching and decrease times.

Peat-based gnotobiotic plant growth systems for Arabidopsis microbiome research.

The complex structure and function of a plant microbiome are driven by many variables, including the environment, microbe-microbe interactions and host factors. Likewise, resident microbiota can influence many host phenotypes. Gnotobiotic growth systems and controlled environments empower researchers to isolate these variables, and standardized methods equip a global research community to harmonize protocols, replicate experiments and collaborate broadly. We developed two easily constructed peat-based gnotobiotic growth platforms: the FlowPot system and the GnotoPot system. Sterile peat is amenable to colonization by microbiota and supports growth of the model plant Arabidopsis thaliana in the presence or absence of microorganisms. The FlowPot system uniquely allows one to flush the substrate with water, nutrients and/or suspensions of microbiota via an irrigation port, and a mesh retainer allows for the inversion of plants for dip or vacuum infiltration protocols. The irrigation port also facilitates passive drainage, preventing root anoxia. In contrast, the GnotoPot system utilizes a compressed peat pellet, widely used in the horticultural industry. GnotoPot construction has fewer steps and requires less user handling, thereby reducing the risk of contamination. Both protocols take up to 4 d to complete with 4-5 h of hands-on time, including substrate and seed sterilization. In this protocol, we provide detailed assembly and inoculation procedures for the two systems. Both systems are modular, do not require a sterile growth chamber, and cost less than US$2 per vessel.

Sequential Abiotic‐Biotic Processes Drive Organic Carbon Transformation in Peat Bogs

AbstractPeatlands, which store one third of the terrestrial carbon (C), are subject to large disturbances under a changing climate. It is crucial to understand how microbial and physiochemical factors affect the vulnerability of these large C stores to predict climate‐induced greenhouse gas fluxes. Here, we used a combination of mass spectrometry and spectroscopy techniques, to understand sequential biotic and abiotic degradation pathways of Sphagnum fallax leachate in an anaerobic incubation experiment, in the presence and absence of microorganisms. Removal of microorganisms was carried out by passing aqueous samples through 0.2‐µm filters. Our results revealed that S. fallax leachate degradation by abiotic reactions is a significant contributor to CO2 production. Further, abiotic factors, such as low pH, are responsible for partial dissolved organic carbon (DOC) degradation that produces bioavailable compounds that shift microbial metabolic pathways and stimulate respiration in peat bogs. Acid‐catalyzed hydrolysis of Sphagnum‐ produced glycosides can provide the microbial communities with glucose and stimulate microbial respiration of DOC to CO2. These results, while unique to peatlands, demonstrate the importance and underscore the complexity of sequential abiotic and biotic processes on C cycling in peat bogs. It is therefore crucial to incorporate abiotic degradation and sequential below‐ground biotic and abiotic interactions into climate models for a better prediction of the influence of climate change on DOC stability in peatlands. These findings might not be representative of other ecosystems with different environmental conditions including mineral‐rich peatlands and plant matter in surface peat horizons that comprise discrete microbial populations, and DOC composition.

Social, nutritional, and behavioral aspects associated with erosive tooth wear - considerations and preventive aspects

Erosive tooth wear is a multifactorial condition resulting from the loss of mineralized dental structure by chemical, physical and / or mechanical processes, in the absence of microorganisms (biofilm), being modulated by biological, behavioral and occupational factors. The increase in the prevalence of non-carious tooth wear is mainly related to changes in eating habits, lifestyle and behavior in the last three decades, which has been cause for concern by the dental community. Due to the increase in life expectancy, especially in more developed countries, maintaining oral health is essential to improve quality of life and prevent comorbidities, increase self-esteem, in addition to improving chewing, speech and social life. Currently, the diagnosis of erosive tooth wear is based on clinical aspects of the lesions, however, knowing the factors associated with nutrition, occupation and lifestyle are essential to define the risk and the susceptibility of the patient to the development of lesions and indication of preventive measures and control. In view of the increase in its incidence and prevalence in young adults, the dental surgeon must know about its etiology, prevention, and treatment. Still, public policies focused on this issue need to be created and adopted. Thus, this study describes the main etiological, nutritional, behavioral, and social aspects associated with non-carious tooth wear, offering important information regarding treatment and mainly prevention.

High resolution microscopy to evaluate the efficiency of surface sterilization of Zea Mays seeds.

Surface sterilization of seeds is a key step in providing microorganisms-free seeds for numerous applications like understanding the role of seed-borne microorganisms in plant development, studying microbial cells-plant interactions by inoculating model microorganisms in a simplified system or selective cultivation of seed endobionts. However applying efficient treatment for surface sterilization of seeds without affecting the plant growth is not an easy task. In this study we aimed to provide an efficient surface sterilization treatment for maize seeds using i) hydrogen peroxide (HP), ii) sodium hypochlorite (SH) and iii) ethanol-sodium hypochlorite (EtOH-SH) under stirring (st) and vacuum-stirring (va-st) conditions. We used fluorescence microscopy and ultra-high resolution Helium Ion Microscopy (HIM) as powerful imaging approaches in combination with macroscopic techniques to visualize, quantify and evaluate the efficiency of seed sterilization, quality of root germination, seedlings and root hair development as well as the presence or absence of microorganisms on the root surface. Our results showed a strong reduction in microbial cell numbers of 4 orders of magnitude after the EtOH-SH treatments. Moreover, seeds exposed to EtOH-SH treatments displayed the lowest percentage of microbial growth (50%) and the highest percentage of germinated seeds (100%) compared to other sterilization treatments. HIM imaging proved the absence of microbial cells on the roots grown from seeds exposed to EtOH-SH treatments. Moreover, root hair development seemed not to be affected by any of the sterilization treatments. Our findings demonstrated that EtOH-SH treatments are significantly reducing the abundance of microbial cells from the surface of maize seeds and can be used with high confidence in future studies.

Effect of low temperature on abiotic and biotic nitrate reduction by zero-valent Iron

The effect of low temperatures on abiotic and biotic nitrate (NO3−) reduction by zero-valent iron (ZVI) were examined at temperatures below 25 °C. The extent and rate of nitrate removal in batch ZVI reactors were determined in the presence and absence of microorganisms at 3.5, 10, 17, and 25 °C. Under anoxic conditions, NO3− reduction rates in both ZVI-only and ZVI-cell reactors declined as temperature decreased. In ZVI-only reactor, 62% and 17% of initial nitrate concentration were reduced in 6 days at 25 and 3.5 °C, respectively. The reduced nitrate was completely recovered as ammonium ions (NH4+) at both temperatures. The temperature-dependent abiotic reduction rates enabled us to calculate the activation energy (Ea) using the Arrhenius relationship, which was 50 kJ/mol. Nitrate in ZVI-cell reactors was completely removed within 1–2 days at 25 and 10 °C, and 67% of reduction was achieved at 3.5 °C. Only 18–25% of the reduced nitrate was recovered as NH4+ in the ZVI-cell reactors. Soluble iron concentrations (Fe2+ and Fe3+) in the ZVI reactors were also measured as the indicators of anaerobic corrosion. In the ZVI-cell reactors, soluble iron concentrations were 1.7 times higher than that in ZVI-only reactors at 25 °C, suggesting that the enhanced nitrate reduction in the ZVI-cell reactors may be partly due to increased redox activity (i.e., corrosion) on iron surfaces. Anaerobic corrosion of ZVI was also temperature-dependent as substantially lower concentrations of corrosion product were detected at lower incubation temperatures; however, microbially induced corrosion (MIC) of ZVI was much less impacted at lower temperatures than abiotic ZVI corrosion. This study demonstrated that ZVI-supported microbial denitrification is not only more sustainable at lower temperatures, but it becomes more dominant reaction for nitrate removal in microbial-ZVI systems at low temperatures.

Synergy effect of peroxidase enzymes and Fenton reactions greatly increase the anaerobic oxidation of soil organic matter

In temperate rainforest soils of southern Chile (38 °S), there are high rates of soil organic carbon (SOC) mineralization under oxygen (O2) limitation. We study the combined effects of Fenton reactions and the activity of two enzymes manganese peroxidase (MnP) and lignin peroxidase (LiP), which was hypothesised potentiate SOC mineralization under anoxic conditions leading to carbon dioxide (CO2) release. Both mechanisms produce free radicals when competing for SOC oxidation in the absence of microorganisms. We quantify the CO2 release by induced Fenton reactions in combination with MnP and LiP under aerobic and anaerobic conditions (20 °C, 36 h) in temperate rainforest soils. CO2 levels released by Fenton reactions and enzyme activity were eight times higher than those released by Fenton reaction and peroxidase enzymes in individual treatment. Approximately 31% of the CO2 released under aerobic soil incubation was found to be abiotic (sterilized), while 69% was biotic (non-sterilized soils), and respective values of 17% and 83% were recorded under anaerobic conditions. The relative fluorescence intensity clearly shows ·OH radicals production from Fenton reactions. In conclusion, levels of MnP and LiP coupled with Fenton reactions strongly increase SOC mineralization under long periods of O2 limitation in temperate rainforest soils.

Implementation and microbiological stability of dose-banded ganciclovir infusion bags prepared in series by a robotic system

ObjectivesThe implementation of dose-banding (DB) in centralised, pharmacy-based cytotoxic drug preparation units allows the preparation of standardised doses in series. The aim of this study was to evaluate the feasibility...

Effect of bacteria and virus on transport and retention of graphene oxide nanoparticles in natural limestone sediments

This research was conducted to evaluate the effect of co-transport of different-sized microorganisms on graphene oxide nanoparticles (GONPs) transport and retention in saturated pristine and biofilm-conditioned limestone columns. The transport and retention behavior of GONPs was studied in columns in the presence of MS2 -as a nano-sized- and Escherichia coli (E.coli) -as a micro-sized- microorganisms at low and high ionic strength conditions. Results showed no changes in GONPs transport and retention at high ionic strength in the presence of MS2 or E. coli, which was attributed to the effect of high concentration of divalent cation on aggregation of nanoparticles and microorganisms. Furthermore, simultaneous enhanced transport and decreased retention of GONPs in column was observed in the co-presence of microorganisms at low ionic strength. Results revealed that the main mechanism governing increasing GONPs transport in porous media was occupation of reactive surface sites of collectors by microorganisms, which prevented attachment of nanoparticles. The pre-saturation of columns with MS2 and E. coli caused increasing transport of GONPs in the columns, due to the occupation of surface reactive sites. Moreover, conditioning limestone collectors with natural biofilm resulted in the same rates of nanoparticle elution and retention (i.e., in the presence or absence of microorganisms) by straining of GONPs in the inlet end of columns which shows that the biofilm acts as a bio-filter against discharging nanoparticles into the effluents. Finally, from the obtained results, it can be postulated that the presence of microorganisms in a MAR site causes risk of groundwater pollution by toxic nanoparticles.

Compare and evaluate the antibacterial efficacy of sodium hypochlorite and Calendula officinalis against Streptococcus mutans as a root canal irrigating solution: An in vivo study

Aim: Elimination of microorganisms should be of priority in the treatment of any endodontic pathogenic process. The prevalence of microorganisms within the root canal will not cause treatment failures but the absence of microorganisms will certainly lead to success. Materials and Methods: In vivo study was conducted to compare the antibacterial effectiveness of sodium hypochlorite and Calendula officinalis against Streptococcus mutans as root canal irrigants. A total of 40 subjects (older than 18 years of age) were selected with single-rooted teeth, necrotic pulp, and chronic apical periodontitis. Access preparation was carried out, canal was negotiated and sample was taken with paper points before biomechanical preparation. After cleaning and shaping with ProTaper files, irrigation was carried out with sodium hypochlorite and C. officinalis, and was then neutralized with saline and then second sample was taken. Both samples were sent for culturing in pre-reduced medium. Mitis salivarius agar was used for S. mutans, and then calculation of the number of colony forming units per milliliter reduced transport fluid was carried out. Results: The results of the study showed good antibacterial potential for both the medicaments used. Conclusion: Sodium hypochlorite remains the gold standard for bacterial elimination in root canal therapy; however, C. officinalis also has shown promising results and may require further investigation.

Efficacy of alginate- and clay-encapsulated microorganisms on the growth of Araçá-Boi seedlings (<I>Eugenia stipitata</I>)

The present work aimed to evaluate the effects of encapsulated microorganisms on seedlings of Eugenia stipitata , popularly known as araca-boi, to evaluate the interaction between the inoculum and encapsulating agents such as clay and alginate. The experiment was carried out in a completely randomized design using a 3×2 factorial scheme. The treatments were control, inoculum, clay without microbial inoculum, clay with microbial inoculum, alginate without microbial inoculum, and alginate with microbial inoculum. The seedlings were grown under nursery conditions over a period of 3 months. No treatment increased the height, stem diameter, shoot dry matter or root dry matter of the araca-boi seedlings. The use of alginate increased the ammonium content compared to the clay and control treatments. Alginate and clay increased the nitrate content in relation to the control. Alginate increased the total number of bacteria in relation to the clay and control treatments. The application of inoculum combined with alginate increased the nitrate content only in relation to the clay and control treatments. Although the application of inoculum promoted an increase in the nitrate content compared to the uninoculated treatments, there was no effect for the other parameters analyzed. The results suggest that clay and alginate encapsulating agents with the presence or absence of microorganisms may improve some soil parameters.

MICROORGANISMS IN POOL WATER

Recreation is the road that leads to the preservation of health. Today, more than ever, human health is threatened by a lack of physical activity and poor diet. The growing presence of sedentary lifestyle results in obesity, diabetes and cardiovascular disease which make good enough reason to change our behavior and introduce physical activity into everyday life. Physically active patients their cardiovascular risk of death can reduce by 50%66. Pool water is of great importance in achieving physical activity and maintaining and improving the health of individuals. However, the presence of microorganisms in the pool water can pose a significant risk to the user’s health. Contamination of pool water by microorganisms can occur in the absence of adequate disinfection, but also due to unhygienic behavior of pool facilities users. Urine, saliva, sweat and feces are the secretions of the human body that can be potential sources of microorganisms in the pool water, as a result of unhygienic behavior. It is believed that microbial contamination of pool water represents the biggest health risk to users. Therefore, priority is always given to microbiological safety in relation to chemical safety, as confirmed by the World Health Organization. Our study was aimed to determine the presence of unhygienic behavior of users by detecting the presence of microorganisms in adequately treated pool water. In two years, total of 46 samples of pool water were analyzed, by 23 samples in each year of the study. Microbiological analyzes included the determination of the presence of coliform bacteria and the total number of aerobic bacteria. Results of microbiological testing showed the presence of Escherichia coli, as a typical representative of coliform bacteria, in 2 samples. Escherichia coli, if found in pool water which is properly treated, clearly indicates unhygienic behavior of the users. In relation to the total number of aerobic bacteria, the results, in 4 out of 46 samples, showed deviation compared to the limit values defined by the legislation. Based on study results, we can conclude that unhygienic behavior of pool facilities users is present, which clearly confirms the identification of Escherichia coli in the samples. The fact is that legislation does not guarantee proper safety of the pool water, but serves only as an indicator of its quality. The absence of microorganisms, originating from swimmers, can be achieved only by adequate education, which aims to raise awareness and knowledge about the importance of hygienic behavior. It is essential that education includes all population groups in order to achieve the best results.

Evaluation of Factors that may Cause False Positive Growth Signals in Blood Cultures-As the Word 'Factors' will Include Both Microbial and Patients as well as Others

Background: In the present study, it was aimed to identify the microorganism and the factors due to the patients which may cause false positive results in automated blood culture systems, and to evaluate the parameters to be used in interpreting the results correctly. Materials and methods: The study was carried out between 2016-2017. Fully automated Bact/Alert 3D (BioMerieux, France) system was used as the blood culture method. Blood cell counting was evaluated by fluorescence flow cytometry method. When the signal was received from the blood culture system, the presence of microorganism was first investigated using Gram staining. In spite of the presence of a growth signal, the absence of microorganisms in the acridine oranges, gram preparations and the absence of growth in the inoculated plates was accepted as false positivity. These bottles were also subcultured onto a chocolate agar and a Sabouraud Dextrose Agar media, and were incubated for 14 days. Mann Whitney U test and Chi-Square test were used for statistical analysis. Permission was taken with the number 10.03.20707. Results: A total of 9216 aerobic blood cultures were included in the study, 1839 (19.9%) of those indicated a positive growth signal. False positivity was detected in 69 (0.75%) of the blood culture bottles. The mean incubation time for positive growth signal was 20 hours in the bottles giving true positive growth signal, whereas the mean incubation time for positive growth signal was 3 hours in the bottles giving false positive growth signal (p

Hydrodynamics and mass transfer in miniaturized bubble column bioreactors.

Miniaturized bubble columns (MBCs) have different hydrodynamics in comparison with the larger ones, but there is a lack of scientific data on MBCs. Hence, in this study, the effect of gas hold-up, flow regimes, bubble size distribution on volumetric oxygen mass transfer coefficient at different pore size spargers and gas flow rates in MBCs in the presence and absence of microorganisms were investigated. It was found that flow regime transition occurred around low gas flow rates of 1.18 and 0.85cm/s for small (16-40µm) and large (40-100µm) pore size spargers, respectively. Gas hold-up and KLa in MBC with small size sparger were higher than those with larger one, with an increasing effect in the presence of microorganisms. A comparison revealed that the wall effect on the flow regime and gas hold-up in MBCs was greater than bench-scale bubble columns. The KLa values significantly increased up to tenfold using small pore size sparger. In the MBC and stirred tank bioreactors, the maximum obtained cell concentrations were OD600 of 41.5 and 43.0, respectively. Furthermore, it was shown that in MBCs, higher KLa and lower turbulency could be achieved at the end of bubbly flow regime.

Biofilm activity on corrosion of API 5L X65 steel weld bead.

This work aimed to identify microbial colonization and biocorrosion in welded seam areas of API 5 L X65 carbon steel, since microorganisms are ubiquitous and there is a lack of information on their biological and electrochemical interactions with these structures. In the present study, polished and unpolished welded coupons prepared by shielded metal arc welding were assayed to identify the effect of surface roughness and local changes in the metal microstructure on microbial colonization. Experiments were performed in glass cell vessels with fresh and sterile seawater to establish the presence or absence of microorganisms. For comparison, nonwelded coupons were simultaneously tested as a control. On the 15th day, both polished and unpolished welded coupons and the nonwelded coupons immersed in fresh seawater showed microbial colonization, though the corrosion products were more abundant for the welded coupons. Nevertheless, unpolished welded coupons showed a higher predominance of pitting around the beads than polished coupons. These results suggest that filler material creates conditions more favorable for biofilm development, thus intensifying the localized corrosion on the welds. It can be concluded that adhesion and subsequent biocorrosion are directly influenced by surface roughness, whereas microstructural modifications due to welding interfere little with microbial adhesion, regardless of the greater pit depths compared to those of nonwelded coupons. Additionally, although open circuit potential measurements indicated that metal surfaces are protected when coated with biofilms, pitting corrosion was more pronounced in welded coupons immersed in fresh seawater than in those immersed in seawater without microorganisms. Therefore, the use of open circuit analysis alone is not recommended for biocorrosion monitoring of welded coupons.

Two-step washing with commercial vegetable washing solutions, and electrolyzed oxidizing microbubbles water to decontaminate sweet basil and Thai mint: A case study

A study was conducted on pre-washing vegetables with four different kinds of surfactant in the washing solution, followed by an acidic electrolyzed oxidizing microbubbles water (AEO-MB) to compare their efficacy on the decontamination of E. coli and S. Typhimurium on sweet basil and Thai mint. Three commercial surfactants (0.1% v/v) and Tween 80® were applied in pre-washing with a constant rate of shaking at 60 rpm for 3 min, then washed with 40 mg/L of AEO, oxidation reduction potential (ORP) 1130–1180 mV and pH 2.8–3.1, under the continuous generation of MB for 5 min. All surfactants showed no antimicrobial activity but greater decontamination (99.0–99.9%) was observed when two-step washing was applied. Wash water with AEO indicated the absence of microorganisms thus helping to prevent cross-contamination. Our study revealed that pre-washing helped to improve the washing efficacy and to enhance the food safety of sweet basil and Thai mint and the treatment may be suitable for application with household or commercial ready-to-eat produce.

Germination responses of four pioneer plant species after passage through the gut of a frugivorous Neotropical bat

ABSTRACTSeed passage through the guts of bats potentially influences germination in different ways: physically, chemically and biologically. To evaluate the influence of a Neotropical bat on the seed germination of four pioneer plant species, an experiment was conducted. Considering the positive influence of bats on germination and the possibility of observing non-viability caused by microorganisms, we hypothesized that (i) seeds subjected to passage through bat guts without the influence of microorganisms have a higher germination potential. Considering the different ecological requirements for the germination of plant species, we also hypothesized that (ii) the four plant species present different germination parameters. The germination of seeds from feces and fruits in the presence and absence of microorganisms was compared for each plant species and among the four plant species. The ingestion of seeds by bats and the presence of microorganisms either improved or did not influence the germination parameters of plants, but the direction of the effects did not support the hypothesis in all cases. The germination parameters differed among most plant species except between Ficus adhatodifolia and F. guaranitica. Our findings indicate that the influence of bats on seeds depends on the microorganisms and singularities of plant species.