Microbiological Reduction of Molybdenum to Molybdenum Blue as a Sustainable Remediation Tool for Molybdenum: A Comprehensive Review

Molybdenum (Mo) microbial bioreduction is a phenomenon that is beginning to be recognized globally as a tool for the remediation of molybdenum toxicity. Molybdenum toxicity continues to be demonstrated in many animal models of spermatogenesis and oogenesis, particularly those of ruminants. The phenomenon has been reported for more than 100 years without a clear understanding of the reduction mechanism, indicating a clear gap in the scientific knowledge. This knowledge is not just fundamentally important—it is specifically important in applications for bioremediation measures and the sustainable recovery of metal from industrial or mine effluent. To date, about 52 molybdenum-reducing bacteria have been isolated globally. An increasing number of reports have also been published regarding the assimilation of other xenobiotics. This phenomenon is likely to be observed in current and future events in which the remediation of xenobiotics requires microorganisms capable of degrading or transforming multi-xenobiotics. This review aimed to comprehensively catalogue all of the characterizations of molybdenum-reducing microorganisms to date and identify future opportunities and improvements.

Dose-response Evaluation of Propolis Dental Varnish in Children: A Randomized Control Study

Background: Early childhood caries is a sugar-dependent disease with multifactorial modulating factors affecting deciduous dentition. It is defined as the presence of at least one decayed tooth, absence of a tooth due to caries or the existence of a temporary restoration in a tooth in a child between zero and 71 months of age. No BRP varnish was found in intellectual property banks, therefore it was registered and deposited with patent number BR1020160190142. Objective: The objective of this study was to evaluate the dose-response concentration of alcoholic extract of Brazilian red propolis (BRP), in the form of dental varnish, against Streptococcus mutans (S. mutans) in children. Methods: Twenty-four children, aged between 36 and 71 months, of both genders and without caries, were selected to participate in this pilot study and grouped randomly into four groups to receive different concentrations of BRP varnish (1%, 2.5%, 5% and 10%). The varnish was applied to the surface of all second deciduous molars. The antimicrobial activity was observed in saliva, which was collected in two phases: before applying the BRP varnish and after use. Results: There was microbiological reduction of S. mutans in the oral cavity of the children in all the tested concentrations. The highest percentage reduction of S. mutans was observed at the concentration of 2.5% (P = 0.0443). Conclusion: The BRP extract in the form of dental varnish has antimicrobial activity against S. mutans and constitutes a possible alternative in the prevention of dental caries.

Transport and degradation of perchlorate in deep vadose zone: implications from direct observations during bioremediation treatment

An in situ bioremediation experiment of a deep vadose zone (~ 40 m) contaminated with a high concentration of perchlorate (> 25,000 mg L−1) was conducted through a full-scale field operation. Favorable environmental conditions for microbiological reduction of perchlorate were sought by infiltrating an electron donor-enriched water solution using drip irrigation underlying an airtight sealing liner. A vadose-zone monitoring system (VMS) was used for real-time tracking of the percolation process, the penetration depth of dissolved organic carbon (DOC), and the variation in perchlorate concentration across the entire soil depth. The experimental conditions for each infiltration event were adjusted according to insight gained from data obtained by the VMS in previous stages. Continuous monitoring of the vadose zone indicated that in the top 13 m of the cross section, perchlorate concentration is dramatically reduced from thousands of milligrams per liter to near-detection limits with a concurrent increase in chloride concentration. Nevertheless, in the deeper parts of the vadose zone (

The effect of polymer burs on microbiological reduction of carious dentin in deciduous teeth: a systematic review

Background. Polymer bur is a new technology that proposes to conserve the dentin that is capable of remineralization. Aim: To conduct a quantitative systematic review to evaluate the effect of polymer burs on the reduction of Streptococcus mutans and Lactobacillus after dentin carious excavation in deciduous teeth. Methods and Material: Two reviewers performed the database to identify the relevant clinical papers. Only papers in English that compared polymer burs with other caries removal techniques with the microbiological aspects as an outcome were included. Papers that evaluated only permanent teeth were excluded. Risk of bias was also assessed. Individual study effect sizes were calculated using Cohen’s d formula for the comparisons of microorganism reduction before and after carious excavation. Results: The search resulted in 12 non-duplicated papers. After the revision, only 2 were selected. The quantitative evaluation demonstrated that polymer bur reduces microorganism levels in carious dentin. The larger effect size observed was for Streptococcus mutans in the polymer bur technique (r=0.84; d=3.12), followed by Lactobacillus in the carbide bur technique (r=0.83; d=3.03). Conclusion: Polymer burs promoted a significant reduction of microorganism levels, mainly Streptococcus mutans in carious dentin.

MICROBIOLOGICAL REDUCTION OF MONOETHANOLAMINE WASTE TOXICITY / MIKROBIOLOGINIS MONOETILAMINO ATLIEKŲ TOKSIŠKUMO MAŽINIMO BŪDAS / МИКРОБИОЛОГИЧЕСКОЕ СНИЖЕНИЕ ТОКСИЧНОСТИ МОНОЭТИЛЕНАМИННЫХ ОТХОДОВ

Aims of the investigation were to evaluate toxicity of monoethanolamine waste to various microorganisms and plants; and to search for means accelerating waste biodegradation. The results of the investigation show toxic effects of MEA waste on bacteria, fungi and plant seeds at rather low concentrations. Some microorganisms are able to adapt to the pollutant in the mixed substrates of the MEA and peat. During the experiment, density of the bacterial and fungal populations in the MEA and peat mixed substrates increased, followed by the intensive acidifying process of the substrates and by the degradation of pollutant. Strong negative effect of MEA waste on peat microbial communities was determined during the first day of the experiment; respiration rate significantly decreased as compared with peat control. Inhibition rate depended on the MEA waste content in the mixture, peat pH and incubation time. After 3–4 days of the incubation, respiration rate of the MEA mixture with acid peat at lower MEA concentration exceeded that of the control by almost five times. Respiration rate of the MEA mixture with neutral peat gradually increased after 4 days of incubation, and was stimulated by the addition of NPK fertilizers. Introduction of yeasts complex and the fungus Trichoderma harzianum accelerated the process of degradation, moreover, the phytotoxicity of the mixed substrate decreased significantly. Santrauka Darbo tikslas – įvertinti monoetilamino (MEA) atliekų toksiškumą įvairių grupių mikroorganizmams ir augalams bei parinkti būdus atliekų biodegradacijai pagreitinti laboratorinėmis sąlygomis. Nustatytas gana mažų koncentracijų MEA dervinių atliekų toksinis poveikis bakterijoms, mielėms, grybams ir augalams. Dalis mikroorganizmų durpių ir MEA mišinyje prisitaiko prie teršalų, didėja jų populiacijos tankis, mažėja substrato pH, o tai rodo MEA atliekų degradaciją, vykstančią dėl mikroorganizmų veiklos. Stiprus mikroorganizmų bendrijos aktyvumą slopinantis MEA poveikis pastebėtas pirmąją eksperimento parą; mikroorganizmų kvėpavimo intensyvumas, palyginti su kontrole, žymiai sumažėjo. Poveikio kvėpavimo intensyvumui mastas priklausė nuo MEA atliekų kiekio mišinyje, durpių pH ir ekspozicijos trukmės. Po trijų parų mikroorganizmų kvėpavimo intensyvumas nedidelės koncentracijos MEA ir rūgščių durpių mišinyje beveik penkis kartus buvo didesnis nei kontrolės. MEA dervos mišiniuose su neutraliomis durpėmis nustatyta palaipsnis kvėpavimo intensyvumo didėjimas substratą papildžius (NPK) trąšomis. Nustatyta, kad introdukavus mielių kompleksą ir mikromicetą Trichoderma harzianum į MEA ir durpių mišinio substratą, mikroorganizmų pradai išlieka gyvybingi ir vystosi, skatindami MEA biodegradaciją. Tai rodo žymiai sumažėjęs su durpėmis sumaišytų MEA atliekų toksiškumas augalams. Резюме Целью работы было оценить токсичность моноэтиленаминных (МЭА) смолистых отходов для разных групп микроорганизмов и растений, а также найти способы ускорения биодеградации этих отходов в лабораторных условиях. Установлено токсичное воздействие сравнительно небольших концентраций МЭА на бактерии, дрожжи,грибы и растения. Часть микроорганизмов в смеси МЭА и торфа приспосабливается к загрязнителям, увеличивается плотность их популяции, рН субстрата меняется в кислотную сторону, что указывает на деградацию МЭА отходов, происходящую благодаря деятельности микроорганизмов. Сильное воздействие МЭА, угнетающее активность сообщества микроорганизмов, наблюдалось в первые сутки эксперимента: интенсивность дыхания посравнению с контрольными данными значительно уменьшилась. Степень воздействия на итенсивность дыханиязависела от количества МЭА отходов в смеси, кислотности торфа и времени экспозиции. Спустя трое суток интенсивность дыхания в смеси МЭА отходов небольшой концентрации и торфа с кислой реакцией была почти впять раз больше, чем в контроле. В смеси МЭА и торфа нейтральной реакции установлено постепенное увеличение интенсивности дыхания при обогащении субстрата удобрениями NPK. Установлено, что при интродукциикомплекса дрожжей и микромицета Trichoderma harzianum в субстрат смеси МЭА и торфа их пропагулы остаютсяжизнеспособными и размножаются, способствуя биодеградации МЭА отходов. Данный вывод подтверждает значимое уменьшение токсичности смеси МЭА отходов и торфа по отношению к растениям.

Quality Changes of Fresh Filled Pasta During Storage: Influence of Modified Atmosphere Packaging on Microbial Growth and Sensory Properties

This study evaluated the shelf life of fresh pasta filled with cheese subjected to modified atmosphere packaging (MAP) or air packaging (AP). After a pasteurization treatment, fresh pasta was packaged under a 50/50 N2/CO2 ratio or in air (air batch). Changes in microbial growth, in-package gas composition, chemical—physical parameters and sensory attributes were monitored for 42 days at 4 °C. The pasteurization treatment resulted in suitable microbiological reduction. MAP allowed a mold-free shelf life of the fresh filled pasta of 42 days, whereas air-packaged samples got spoilt between 7 and 14 days. The hurdle approach used (MAP and low storage temperature) prevented the growth of pathogens and alterative microorganisms. MAP samples maintained a high microbiological standard throughout the storage period. The panel judged MAP fresh pasta above the acceptability threshold throughout the shelf life.