Isolation and characterization of a Rhodococcus strain with phenol-degrading ability and its potential use for tannery effluent biotreatment

Introduction

Wastewater derived from leather production may contain phenols, which are highly toxic, and their degradation could be possible through bioremediation technologies.

Materials, methods and results

In the present work, microbial degradation of phenol was studied using a tolerant bacterial strain, named CS1, isolated from tannery sediments. This strain was able to survive in the presence of phenol at concentrations of up to 1,000?mg/L. On the basis of morphological and biochemical properties, 16S rRNA gene sequencing, and phylogenetic analysis, the isolated strain was identified as Rhodococcus sp. Phenol removal was evaluated at a lab-scale in Erlenmeyer flasks and at a bioreactor scale in a stirred tank reactor. Rhodococcus sp. CS1 was able to completely remove phenol in a range of 200 to 1,000?mg/L in mineral medium at 30 ± 2?°C and pH 7 as optimal conditions. In the stirred tank bioreactor, we studied the effect of some parameters, such as agitation (200?C600 rpm) and aeration (1?C3?vvm), on growth and phenol removal efficiency. Faster phenol biodegradation was obtained in the bioreactor than in Erlenmeyer flasks, and maximum phenol removal was achieved at 400?rpm and 1 vvm in only 12?h. Furthermore, Rhodococcus sp. CS1 strain was able to grow and completely degrade phenols from tannery effluents after 9?h of incubation.

Conclusion

Based on these results, Rhodococcus sp. CS1 could be an appropriate microorganism for bioremediation of tannery effluents or other phenol-containing wastewaters.     

Evaluation of a bioassays battery for ecotoxicological screening of marine sediments from Ionian Sea (Mediterranea Sea, Southern Italy)

Sediments are an ecologically important component of the aquatic environment and may play a key role in mediating the exchange of contaminants between particulate, dissolved, and biological phases. For a comprehensive assessment of potential sediment toxicity, the use of a single species may not detect toxicant with a specific mode of action. Therefore it is advisable to carry out ecotoxicological tests on a base-set of taxa utilizing test species belonging to different trophic levels. This paper describes the ecotoxicological evaluation of marine sediments from seven sites of Mar Piccolo estuary (Southern, Italy), four of them were located in the first inlet and three in the second inlet of Mar Piccolo estuary. Sediment samples from a site in Taranto Gulf were used as control sediment. Dunaliella tertiolecta, Tigriopus fulvus, Mytilus galloprovincialis, and Corophium insidiosum, were employed to identify the quality of sediments. The integration of biological tests results showed that all sampling sites located in the first inlet of Mar Piccolo were identified as toxic, according to all tests, while the sites of second inlet were found not toxic. The results obtained in this study indicate that the use of a battery of biological tests have important implications for risk assessment in estuarine e coastal waters.     

Comparison of criteria for prediction of runaway reactions in the sulphuric acid catalyzed esterification of acetic anhydride and methanol

Loss of temperature control is one of the major reasons that can lead to runaway reaction. This occurrence is commonly named thermal runway. The aim of this paper is the application of thermal runaway criteria in order to predict the onset of runaway phenomena and define the range of stability related to operating conditions in the reactor, with specific reference to the esterification of acetic anhydride and methanol catalysed by sulphuric acid tested in isoperibolic conditions. The isoperibolic calorimeter has also been used to obtain thermodynamic, kinetic and physical chemistry data necessary to develop a model for the reaction. Some runaway criteria applied in this work require a model for the process, so a model for the analyzed system been developed.Because of the modest reaction enthalpy and low activation energy this reacting system provide a severe test to the runaway criteria.In this work, various runaway criteria have been applied to the experimental and simulated data and the results obtained have been compared.     

Brassica napus hairy roots and rhizobacteria for phenolic compounds removal

Phenolic compounds are contaminants frequently found in water and soils. In the last years, some technologies such as phytoremediation have emerged to remediate contaminated sites. Plants alone are unable to completely degrade some pollutants; therefore, their association with rhizospheric bacteria has been proposed to increase phytoremediation potential, an approach called rhizoremediation. In this work, the ability of two rhizobacteria, Burkholderia kururiensis KP 23 and Agrobacterium rhizogenes LBA 9402, to tolerate and degrade phenolic compounds was evaluated. Both microorganisms were capable of tolerating high concentrations of phenol, 2,4-dichlorophenol (2,4-DCP), guaiacol, or pentachlorophenol (PCP), and degrading different concentrations of phenol and 2,4-DCP. Association of these bacterial strains with B. napus hairy roots, as model plant system, showed that the presence of both rhizospheric microorganisms, along with B. napus hairy roots, enhanced phenol degradation compared to B. napus hairy roots alone. These findings are interesting for future applications of these strains in phenol rhizoremediation processes, with whole plants, providing an efficient, economic, and sustainable remediation technology.     

Is there still a role for nuchal translucency measurement in the changing paradigm of first trimester screening?

Objectives

To give an overview of the genetic and structural abnormalities occurring in fetuses with nuchal translucency (NT) measurement exceeding the 95th percentile at first-trimester screening and to investigate which of these abnormalities would be missed if cell-free fetal DNA (cfDNA) were used as a first-tier screening test for chromosomal abnormalities.

Methods

This is a national study including 1901 pregnancies with NT≥95th percentile referred to seven university hospitals in the Netherlands between 1 January 2010 and 1 January 2016. All cases with unknown pregnancy outcome were excluded. Results of detailed ultrasound examinations, karyotyping, genotyping, pregnancy and neonatal outcomes, investigation by a clinical geneticist and post-mortem investigations were collected.

Results

In total, 821 (43%) pregnancies had at least one abnormality. The rate of abnormalities was 21% for fetuses with NT between 95^th and 99^th percentile and 62% for fetuses with NT≥99^th percentile. Prevalence of single-gene disorders, submicroscopic, chromosomal and structural abnormalities was 2%, 2%, 30% and 9%, respectively.

Conclusion

Although cfDNA is superior to the combined test, especially for the detection of trisomy 21, 34% of the congenital abnormalities occurring in fetuses with increased NT may remain undetected in the first trimester of pregnancy, unless cfDNA is used in combination with fetal sonographic assessment, including NT measurement.     

Noninvasive screening by cell-free DNA for 22q11.2 deletion: Benefits,limitations, and challenges

Cell-free DNA (cfDNA) testing for fetal aneuploidy is one of the most important technical advances in prenatal care. Additional chromosome targets beyond common aneuploidies, including the 22q11.2 microdeletion, are now available because of this clinical testing technology. While there are numerous potential benefits, 22q11.2 microdeletion screening using cfDNA testing also presents significant limitations and pitfalls. Practitioners who are offering this test should provide comprehensive pretest and posttest prenatal counselling. The discussion should include the possibility of an absence of a result, as well as the risk of possible discordance between cfDNA screening results and the actual fetal genetic chromosomal constitution. The goal of this review is to provide an overview of the cfDNA testing technologies for 22q11.2 microdeletions screening, describe the current state of test validation and clinical experience, review “no results” and discordant findings based on differing technologies, and discuss management options.