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Biopolymers are biodegradable and renewable and can significantly reduce environmental impacts. For this reason, biocomposites based on a plasticized starch and cross-linker matrix and with a microfibrillated OCC cardboard cellulose reinforcement were developed. Biocomposites were prepared by suspension casting with varied amounts of microfibrillated cellulose: 0, 4, 8, and 12 wt%. Polyethylene glycol diglycidyl ether (PEGDE) was used as a cross-linking, water-soluble, and non-toxic agent. Microfibrillated cellulose (MFC) from OCC cardboard showed appropriate properties and potential for good performance as a reinforcement. In general, microfiber incorporation and matrix cross-linking increased crystallization, reduced water adsorption, and improved the physical and tensile properties of the plasticized starch. Biocomposites cross-linked with PEGDE and reinforced with 12 wt% MFC showed the best properties. The chemical and structural changes induced by the cross-linking of starch chains and MFC reinforcement were confirmed by FTIR, NMR, and XRD. Biodegradation higher than 80% was achieved for most biocomposites in 15 days of laboratory compost.

In this work, cellulose nanocrystals (CNCs), bleached cellulose nanofibers (bCNFs), and unbleached cellulose nanofibers (ubCNFs) isolated by acid hydrolysis from Agave tequilana Weber var. Azul bagasse, an agro-waste from the tequila industry, were used as reinforcements in a thermoplastic starch matrix to obtain environmentally friendly materials that can substitute contaminant polymers. A robust characterization of starting materials and biocomposites was carried out. Biocomposite mechanical, thermal, and antibacterial properties were evaluated, as well as color, crystallinity, morphology, rugosity, lateral texture, electrical conductivity, chemical identity, solubility, and water vapor permeability. Pulp fibers and nanocelluloses were analyzed via SEM, TEM, and AFM. The water vapor permeability (WVP) decreased by up to 20.69% with the presence of CNCs. The solubility decreases with the presence of CNFs and CNCs. The addition of CNCs and CNFs increased the tensile strength and Young's modulus and decreased the elongation at break. Biocomposites prepared with ubCNF showed the best tensile mechanical properties due to a better adhesion with the matrix. Images of bCNF-based biocomposites demonstrated that bCNFs are good reinforcing agents as the fibers were dispersed within the starch film and embedded within the matrix. Roughness increased with CNF content and decreased with CNC content. Films with CNCs did not show bacterial growth for Staphylococcus aureus and Escherichia coli . This study offers a new theoretical basis since it demonstrates that different proportions of bleached or unbleached nanofibers and nanocrystals can improve the properties of starch films.

Background: The demand for clinical trial participants is today one of the highest it has ever been and continues to increase. At the same time, subject recruitment continues to be problematic and the major reason for clinical trial premature terminations. The literature on clinical trial recruitment, which spans several decades and includes hundreds of studies, has an abundance of findings that can be synthesized by way of an overview to provide a well-informed and complete picture of the factors that determine subject participation., Objectives: An overview of the systematic reviews that report barriers and facilitators to clinical trial participation was conducted. The extracted data were synthesized, and a thematic framework of the factors that affect subject participation in clinical trials was developed. The overview extended across medical subjects and demographics., Methods: Thirty reviews that complied with the inclusion criteria were included. These reviews covered 753 relevant primary studies and reported 881 barriers and facilitators. The barriers and facilitators were thematically synthesized and a thematic framework of 20 themes was developed. The quality of the included reviews was assessed and reported., Main Results: Several opportunities to increase clinical trial participation, by developing interventions and changing the trial design, derived from an analysis of the thematic framework. That analysis also showed that most of the 20 themes operate mainly as a barrier or as a facilitator, and that most have an effect across medical subjects. As to the quality elements assessed, some reviews complied almost fully but most only partially., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Authors. Published by Elsevier Inc.)

There has been a growing interest in the degradation of 2,4,6-trinitrotoluene (TNT) over the last decade, ever since its removal from polluted sites was declared an international environmental priority. Certain aerobic and anaerobic microorganisms are capable of using TNT as an N source, although very few studies have proven the mineralization of this compound. An unexpected observation in our laboratory led us to discover that certain Escherichia coli bench laboratory strains have multiple enzymes that attack TNT. One of the NemA products is responsible for the release of nitrite from the nitroaromatic ring: among the metabolites observed in vitro include Meisenheimer dihydride complexes of TNT from which 2-hydroxylamino-6-nitrotoluene is slowly formed during their rearomatization under concomitant release of nitrite. Furthermore, NemA, together with NfsA and NfsB reduce the nitro groups on the aromatic ring to the corresponding hydroxylamino derivatives, which probably results in the release of ammonium ions which can, in turn be used as a nitrogen source by E. coli for growth.

Industrialization and the quest for a more comfortable lifestyle have led to increasing amounts of pollution in the environment. To address this problem, several biotechnological applications aimed at removing this pollution have been investigated. Among these pollutants are xenobiotic compounds such as polynitroaromatic compounds--recalcitrant chemicals that are degraded slowly. Whereas 2,4,6-trinitrophenol (TNP) can be mineralized and converted into carbon dioxide, nitrite and water, 2,4,6-trinitrotoluene (TNT) is more recalcitrant--although several microbes can use it as a nitrogen source. The most effective in situ biotreatments for TNT are the use of bioslurry (which can be preceded by an abiotic step) and phytoremediation. Phytoremediation can be enhanced by using transgenic plants alone or together with microbes.

XylS controls the expression of the meta-cleavage pathway for the metabolism of benzoates in Pseudomonas putida KT2440. The xylS gene is expressed from two promoters, Ps1 and Ps2. Transcription from Ps2 is low and constitutive, whereas transcription from Ps1 is induced in the presence of toluene. In this study, we also show that translation of mRNA generated from Ps1 is 10 times more efficient than that generated from Ps2. This pattern of transcription and translation of xylS gives rise to two modes of activation of the promoter of the meta pathway operon (Pm) according to the concentration of XylS in the cell. In cells growing with benzoate, with small amounts of XylS, the activated XylS regulator binds the effector and stimulates transcription from Pm, whereas in cells growing with toluene, the high levels of XylS suffice to stimulate transcription from Pm even in the absence of XylS effectors.

Transcription from the TOL plasmid meta-cleavage pathway operon, Pm, depends on the XylS protein being activated by a benzoate effector. The XylS binding sites are two imperfect 5'-TGCAN(6)GGNTA-3' direct repeats located between positions -70/-56 and -49/-35 [González-Pérez et al. (1999) J. Biol. Chem. 274, 2286-2290]. An intrinsic bending of 40 degrees, which is not essential for transcription, is centered at position -43. We have determined the potential overlap between the XylS and RNA polymerase binding sites. The insertion of 2 or more bp between C and T at positions -37 and -36 abolished transcription activation by the wild-type XylS and by XylSS229I, a mutant with increased affinity for the XylS binding sites. In contrast, a 1-bp insertion at -37 was permissible, although when in addition to the 1-bp insertion at -37 the mutant promoter had a point mutation at the XylS binding site (C-47-->T), transcription was abolished with the wild-type XylS protein, but not with XylSS229I. The overlap between the proximal XylS binding site and the -35 region recognized by RNA polymerase at positions -35 and -36 appears to be critical for transcription.

The Pm promoter of the TOL plasmid of Pseudomonas putida is expressed at high level along the growth curve. This transcription is dependent on the positive regulator XylS activated by 3-methylbenzoate. The sigma factor sigma 38 is required for expression in early stationary phase and thereafter. To test whether sigma 70 was involved in Pm transcription in exponential phase, we have followed mRNA synthesis in a rpoD thermosensitive strain. No difference in Pm transcription was found between the wild type and the thermosensitive strain at the restrictive temperature of 42 degrees C, indicating that transcription was independent of the sigma factor sigma 70. However, basal levels of mRNA expression from Pm in this strain in exponential phase were more than twofold higher at 42 degrees C, suggesting involvement of sigma 32 in Pm transcription. In a rpoH background, no expression of Pm took place in the exponential phase, whereas it increased during stationary phase, and in a rpoH rpoS double mutant no activity from the Pm promoter was detected along the growth curve. We have shown that the increase in the amount of sigma 32 factor necessary for transcription in exponential phase is provided through induction of the heat shock response by the presence of the effector 3-methylbenzoate, which is also required for activation of the positive regulator XylS. We conclude that activation of Pm transcription is achieved through a switch between two stress-responsive factors, sigma 32 in exponential phase and sigma 38 in stationary phase. In both cases, transcription is dependent on the activator XylS and presents the same transcription start point.

The Pm promoter, dependent on TOL plasmid XylS regulator, which is activated by benzoate effectors, drives transcription of the meta-cleavage pathway for the metabolism of alkylbenzoates. This promoter is unique in that in vivo transcription is mediated by RNA-polymerase with different sigma factors. In vivo footprinting analysis shows that XylS interacted with nucleotides in the -40 to -70 region. In vivo and in vitro methylation of Pm shows extensive methylation of T at position -42 in the bottom strand, suggesting that it represents a key distortion point that may favor XylS/RNA polymerase interactions. Methylation of T-42 was highest in cells bearing XylS and in the presence of an effector. Gs in the -47 to -61 region appeared to be more protected in cells harboring XylS in the presence than in the absence of the effector. Almost 100 mutants in the Pm region between -41 and -78 were generated; transcriptional analysis of these mutants defined the XylS target as two direct repeats with the sequence TGCAN6GGNCA. These motifs cover the -70 to -56 and the -49 to -35 regions. Single point mutations revealed that nucleotides located at -49 to -46 and at -59, -60, -62, and -70 are the most critical for appropriate XylS-Pm interactions.