New insights in agar biorefinery with arylsulphatase activities

International audienceAgar is a major gelling agent used both in food and pharmaceutical applications. Traditional purification of agar is generally performed by sequential time consuming chemical and/or physical steps, leading to both poor recovery yields and low productivities. As a consequence, only 30% of the amount of agar produced is actually available under purified form to feed the world market. The current limiting factor for purification is the presence of sulphated compounds such as sulphated-agaropectin, which strongly affect the technological properties of the agar gel such as gel strength, melting and fusion temperatures and electroendosmosis. In this context, this communication aims at discussing about the development of a biorefining agar purification approach which allows overcoming the current limitations associated with traditional purification methods. More specifically, this article focuses on the potential role of arylsulphatases in agar purification processes to reduce the number of purification steps and to improve recovery yields. This review first presents the global gelling agents market before focusing on agar characteristics and production processes. Then, after a brief reminder of the sulphur metabolism, the roles, classes and properties of the different arylsulphatases are described to draw perspectives on their integration in current or new agar production processes

Coupling traditional biodegradation assessments with spectroscopic tools for plastic wastes: case of Polyurethane wastes assessment

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High throughput microbial array for complex matrix assessment

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Evaluation of Biomonitoring Strategies to Assess Performance of a Bioremediation Bioprocess

This study was conducted to propose a suitable set of methods to evaluate the efficiency of two biotreatments. For this purpose, two sets of four 7.5 L bioreactors were followed over 90 days, containing natural sediments from the Bizerte Lagoon (Tunisia) contaminated with 35 mg·kg−1 benzo(a)pyrene (BaP) and 28 mg·kg−1 dichlorodiphenyltrichloroethane (DDT). One set was biostimulated with N/P and bioaugmented with the indigenous Pseudomonas stutzeri, Cupriavidus metallidurans and Rhodococcus equi, and the other set was only biostimulated. In the effluent, organic carbon decreased from 42 gC·L−1 to 0.2 gC·L−1 for the bioaugmented treatment compared to 15 gC·L−1 for biostimulation. Statistical analyses confirmed a significant difference in BaP concentration after bioaugmention from 35 mg·kg−1 to 21 mg·kg−1 sediment, whereas no difference was found with biostimulation. Considering DDT, biostimulation was more efficient (8.5 mg·kg−1 sediment final concentration) than bioaugmentation (15 mg·kg−1 final concentration). Native organotin and metals were also monitored using bioluminescent bioreporter strains. The bioaugmented treatment brought about a significant decrease in TBT content, to below 0.01 µM, whereas its concentration remained significant after biostimulation. The biostimulation did not alter As3+, Cu2+, Cd2+, and Hg2+ concentrations, whereas bioaugmentation induced a decrease of 1 to 2 log for each metal. At the end of the experimental period, toxicity decreased to 90% in the effluent of the bioaugmented reactors compared with a drop of only 48% for biostimulation, and a significant decrease in mutagenicity appeared for bioaugmention only. Interestingly, not all the strains used in the treatments were maintained, as P. stutzeri and R. equi increased up to densities of 8.3 × 1013 and 5.2 × 1012 DNA·g−1 sediment, respectively, while in both treatments, C. metallidurans decreased down to the detection threshold. Among the different methods used, a restricted monitoring panel of analyses appears essential to follow the change occurring over the bioremediation process: (i) organic carbon measurement reporting all biodegradation events, as well as a specific method to monitor the main compounds; (ii) dissolved N, P, O2 and pH measurements, (iii) a qPCR method to track the degraders; and (iv) measurements of the acute toxicity and the mutagenicity

Coupling traditional biodegradation assessments with spectroscopic tools for plastic wastes: case of Polyurethane wastes assessment.

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Applying Raman spectroscopy to the assessment of the biodegradation of industrial polyurethanes wastes

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Density, structure, and diversity of the cultivable arylsulfatase-producing bacterial community in the rhizosphere of field-grown rape and barley

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High throughput and miniaturised systems for biodegradability assessments

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Effect of primary mild stresses on resilience and resistance of the nitrate reducer community to a subsequent severe stress

International audienceThe factors regulating soil microbial stability (e.g. resistance and resilience) are poorly understood, even though microorganisms are essential for ecosystem functioning. In this study, we tested whether a functional microbial community subjected to different primary mild stresses was equally resistant or resilient to a subsequent severe stress. The nitrate reducers were selected as model community and analysed in terms of nitrate reduction rates and genetic structure by narG PCR-restriction fragment length polymorphism fingerprinting. Heat, copper and atrazine were used as primary stresses and mercury at a high concentration as a severe stress. None of the primary stresses had any significant impact on the nitrate reducer community. Although primary stress with heat, copper or atrazine had no effect on the resilience of the nitrate reducer activity to mercury stress, pre-exposure to copper, another heavy metal, resulted in increased resilience. In contrast, the resistance of both structure and activity of the nitrate reducer community to severe mercury stress was not affected by any of the primary stresses tested. Our experiment suggests that the hypothetical effect of an initial stress on the response of a microbial community to an additional stress is complex and may depend on the relatedness of the two consecutive stresses and the development of positive cotolerance

Solving complexity of biodegradation assessments for UVCB chemicals usingan automated system: EVABIO

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