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Toehold switches are biosensors useful for the detection of endogenous and environmental RNAs. They have been successfully engineered to detect virus RNAs in cell-free gene expression reactions. Their inherent sequence programmability makes engineering a fast and predictable process. Despite improvements in the design, toehold switches suffer from leaky translation in the OFF state, which compromises the fold change and sensitivity of the biosensor. To address this, we constructed and tested signal amplification circuits for three toehold switches triggered by Dengue and SARS-CoV-2 RNAs and an artificial RNA. The serine integrase circuit efficiently contained leakage, boosted the expression fold change from OFF to ON, and decreased the detection limit of the switches by 3-4 orders of magnitude. Ultimately, the integrase circuit converted the analog switches' signals into digital-like output. The circuit is broadly useful for biosensors and eliminates the hard work of designing and testing multiple switches to find the best possible performer.

Caiman meat is considered exotic and its consumption has significantly increased due to its nutritional quality. This study aimed to evaluate the kinetics of water content (WC) and salt content (SC) at different temperatures (1, 5, 10 and 15 °C) and to evaluate the use of mathematical models to predict the mass transfer kinetics until equilibrium conditions during the wet salting of caiman tail fillets. Moisture and chloride analyses were performed throughout the wet salting process. Four models (Peleg; Weibull; Zugarramurdi and Lupín; Diffusion) were tested to predict WC and SC kinetics in caiman tail fillets subjected to wet salting. The increase in the temperature resulted in a reduction (P < 0.05) in WC and an increase (P < 0.05) in SC. Nonlinear effects on WC and SC kinetics were observed between the different temperatures evaluated. Furthermore, the effective diffusion coefficients (D w and D s ) increased (P < 0.05) with increasing temperature. Peleg, Weibull, Zugarramurdi and Lupín, and the Diffusion model satisfactorily represented WC and SC rates throughout the process. The kinetic behavior of the parameters of the models corroborated the effects of temperature on those parameters. Peleg was the best model for predicting WC and SC kinetics, and Zugarramurdi and Lupín was the best for predicting the equilibrium conditions of the process (WC ∞ SC ∞ ), all parameters which can be used to describe the mass transfer kinetics during wet salting of caiman tail fillets., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In the past decades, the production of biopharmaceuticals has gained high interest due to its great sensitivity, specificity, and lower risk of negative effects to patients. Biopharmaceuticals are mostly therapeutic recombinant proteins produced through biotechnological processes. In this context, L-asparaginase (L-asparagine amidohydrolase, L-ASNase (E.C. 3.5.1.1)) is a therapeutic enzyme that has been abundantly studied by researchers due to its antineoplastic properties. As a biopharmaceutical, L-ASNase has been used in the treatment of acute lymphoblastic leukemia (ALL), acute myeloblastic leukemia (AML), and other lymphoid malignancies, in combination with other drugs. Besides its application as a biopharmaceutical, this enzyme is widely used in food processing industries as an acrylamide mitigation agent and as a biosensor for the detection of L-asparagine in physiological fluids at nano-levels. The great demand for L-ASNase is supplied by recombinant enzymes from Escherichia coli and Erwinia chrysanthemi. However, production processes are associated to low yields and proteins associated to immunogenicity problems, which leads to the search for a better enzyme source. Considering the L-ASNase pharmacological and food importance, this review provides an overview of the current biotechnological developments in L-ASNase production and biochemical characterization aiming to improve the knowledge about its production. KEY POINTS: • Microbial enzyme applications as biopharmaceutical and in food industry • Biosynthesis process: from the microorganism to bioreactor technology • Enzyme activity and kinetic properties: crucial for the final application.

The aim of this work was to evaluate the antioxidant effect of acerola fruit powder, rosemary and licorice extract in caiman meat nuggets containing high amounts of mechanically separated caiman meat (MSCM) during 120 days of frozen storage. Five treatments were prepared: a control without antioxidant (CON), sodium erythorbate at 500 mg/kg (ERY), acerola fruit powder at 500 mg/kg (AFP), with licorice extract at 500 mg/kg (LIE) and rosemary extract at 500 mg/kg (ROE). The addition of natural antioxidants increased color, cohesiveness, and decreased TBARS values. The redness values were higher for LIE and these values were different to the CON. Nuggets with licorice extract had significantly lower TBARS values at the end of the storage period compared to the control. All the treatments were similar in sensory analysis, with good acceptability. These results indicate licorice extract used in caiman meat nuggets containing a high amount of MSCM caiman has the potential to improve quality during frozen storage., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Intense synthesis of proteins and chemicals in engineered microbes impose metabolic burden, frequently leading to reduced growth and heterogeneous cell population. Thus, the correct balance between growth and production is important. Such balance can be engineered through dynamic control of pathways, but few broadly applicable tools are available to achieve this. We present an autonomous control of gene expression mediated by quorum sensing in Bacillus subtilis, able to self-monitor and induce expression without human supervision. Two variations of the induction module and seven of the response module were engineered generating a range of induction folds and strengths for gene expression control. Our strongest response promoter is 2.5 and 3.2 times stronger than the well-characterized promoters P srfA and P veg , respectively. We applied our strongest autoinduction device for the production of the vitamin B 2 . This study presents a toolbox of autoinduction modules for B. subtilis that is modular and tunable., (Copyright © 2020 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.)

Modular and tuneable genetic tools for Metabolic Engineering fuels the development of chassis for the efficient production of biocompounds at industrial scale. We have constructed an autoinduction device for gene expression in Bacillus subtilis based on the LuxR/I quorum sensing system [1]. Here, we present raw and processed data regarding to B. subtilis growth measured as OD 600 , performed in three different scales: microcultivation on 96-well plates (200 µL), test tubes (12 mL), and Erlenmeyer flasks (50 mL). We also present raw and processed data on gene expression measured as GFP fluorescence (485/535 nm), luminescence and riboflavin production. Measurements were performed on a microplate reader Tecan 200 PRO (iControl software) and on spectrophotometer (Thermo Fisher Scientific GENESYS 10S UV-Vis). Processed data are presented as product/OD 600 , maximum and minimum promoter activity, fold of induction, and the induction OD 600 ., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships which have, or could be perceived to have, influenced the work reported in this article., (© 2020 The Authors.)

Upstream open reading frames (ORFs) are frequently found in the 5'-flanking regions of genes and may have a regulatory role in gene expression. A small ORF (named cohL here) was identified upstream from the copAB copper operon in Xanthomonascitri subsp. citri (Xac). We previously demonstrated that copAB expression was induced by copper and that gene inactivation produced a mutant strain that was unable to grow in the presence of copper. Here, we address the role of cohL in copAB expression control. We demonstrate that cohL expression is induced by copper in a copAB-independent manner. Although cohL is transcribed, the CohL protein is either not expressed in vivo or is synthesized at undetectable levels. Inactivation of cohL (X. citri cohL polar mutant strain) leads to an inability to synthesize cohL and copAB transcripts and consequently the inability to grow in the presence of copper. Bioinformatic tools predicted a stem-loop structure for the cohL-copAB intergenic region and revealed that this region may arrange itself in a secondary structure. Using in vitro gene expression, we found out that the structured 5'-UTR mRNA of copAB is responsible for sequestering the ribosome-binding site that drives the translation of copA. However, copper alone was not able to release the sequence. Based on the results, we speculate that cohL plays a role as a regulatory RNA rather than as a protein-coding gene.