Inactivation Technique Research Articles

Involvement of Pre-limbic Cortex-Nucleus accumbens projections in Context-Induced alcohol seeking

Alcohol use disorder (AUD) remains a critical public health issue worldwide, characterized by high relapse rates often triggered by contextual cues. This research investigates the neural mechanisms behind context-induced reinstatement of alcohol-seeking behavior, focusing on the nucleus accumbens and its interactions with the prelimbic cortex, employing Male Long-Evans rats in an ABA renewal model. In our experimental setup, rats were trained to self-administer 10 % ethanol in Context A, followed by extinction of lever pressing in the presence of discrete cues in Context B. The context-induced reinstatement of ethanol-seeking was then assessed by re-exposing rats to Context A or B under extinction conditions, aiming to simulate the environmental cues’ influence on relapse behaviors. Three experiments were conducted: Experiment 1 utilized Fos-immunohistochemistry to examine neuronal activation in the nucleus accumbens; Experiment 2 applied the baclofen + muscimol inactivation technique to probe the functional importance of the nucleus accumbens core; Experiment 3 used Fos-immunofluorescence along with Retrobeads injection to investigate activation of neurons projecting from the prelimbic cortex to the nucleus accumbens core. Our findings revealed significant increases in Fos-immunoreactive nuclei within the nucleus accumbens core and shell during the reinstatement phase in Context A, underscoring the environment’s potent effect on ethanol-seeking behavior. Additionally, inactivation of the nucleus accumbens core markedly reduced reinstatement, and there was a notable activation of neurons from the prelimbic cortex to the nucleus accumbens core in the ethanol-associated context. These results highlight the critical role of the nucleus accumbens core and its corticostriatal projections in the neural circuitry underlying context-driven ethanol seeking.

Improved production strain maintenance technique for Burkholderia mallei 5584 (Master seed) used for glander diagnostic agent production

One of the aspects important for strain collection maintenance is the optimization of existing methods and development of new techniques for microbial strain preservation, that is why the improvement of previously developed methods for authentic strain preservation is an urgent task. The article provides information on the maintenance of Burkholderia mallei 5584 (Master seed) using previously developed technique, which was supplemented with new stages in accordance with modern requirements for strain collections of highly dangerous disease agents. The previous strain maintenance technique involved its storage in its native state, which facilitated accumulation of genetic mutations and, ultimately modification of bacterial cell properties. To extend the storage time of this strain and to ensure the stability of its biological properties, the freeze-drying method was used. Skimmed milk was used as a cryoprotectant. Freeze-drying was performed under selected conditions. This technique allows for the strain sub-culturing on sensitive models once every 5 years, which is more expedient and safe from an economic and biological point of view. For safe handling of Burkholderia mallei 5584 production strain, an inactivation technique using gamma rays at 30 kGy was developed, which allowed to achieve microbial suspension sterility and preserve the bacterial cell structure. When comparing the previously developed and supplemented techniques, it was found that the improved technique of Burkholderia mallei 5584 (Master seed) maintenance makes it possible to avoid the loss of its biological properties needed for the production of high-quality laboratory diagnostic agents used for timely disease detection in susceptible animals by diagnostic tests.

An Approach to Improve Energy Efficiency during Antimicrobial Blue Light Inactivation: Application of Pulse-Width Modulation Dimming to Balance Irradiance and Irradiation Time.

Antimicrobial blue light (aBL) is an effective non-destructive inactivation technique and has received increasing attention. Despite its significance, the existing research has not thoroughly delved into the impacts of irradiance and irradiation time on enhancing energy efficiency during aBL inactivation and the explanation of the enhancement effect of pulse exposure. In this paper, a series of Escherichia coli inactivation experiments with different duty cycles, pulse frequencies, and irradiation times were conducted, and the relative concentrations of reactive oxygen species (ROS) were measured under corresponding conditions. A two-dimensional (2-D) Hom model was proposed to evaluate the effect of irradiance and irradiation time. The results show that, compared to continuous exposure, pulsed aBL (duty cycle = 25%) can save ~37% of the energy to achieve the same inactivation effect and generate a 1.95 times higher ROS concentration. The 2-D Hom model obtains the optimal combination of average irradiance and time according to the desired reduction and shows that the irradiation time has a higher weight than the irradiance (1.677 and 1.083, respectively). Therefore, using pulse exposure with a lower average irradiance for a longer period of time can achieve a better inactivation effect when consuming equivalent energy. The proposed pulse-width modulation dimming approach helps promote the application of the aBL technique.

Germicidal efficacy of the pulsed magnetic field against pathogens and spoilage microorganisms in food processing: An overview

In addition to excessive use of chemical and physical antiseptics in food, any harmful microorganisms present in food are potentially the cause of food safety issues and even cause foodborne diseases to threaten human health. Thermal processing of food as a conventional sterilization technology has been widely used in the food industry to ensure food safety. However, heat treatment has some inevitable adverse effects on nutrition, flavor, color, texture, and aesthetics of the food products. Therefore, it is necessary to research novel nonthermal, green technologies to minimize the impact of undesirable changes on food, and enhance the inactivation efficiency of microorganisms that can cause foodborne illnesses. This review presents a general perspective of the pulsed magnetic field (PMF) as a novel nonthermal sterilization technology. The operating principle, characteristics, and biological effects on microorganisms of PMF are described. Furthermore, the possible inactivation mechanisms and their application in food processing are also addressed. PMF sterilization is considered to be an effective and efficient microorganism eliminating technology that exerts its germicidal ability by magnetoporation and electromagnetic effects, mainly including induced current effect, Lorentz force effect, oscillation effect, and ionization effect. Compared to thermal treatment, PMF sterilization technique meets the requirements of commercial food sterilization standards without impacting food flavor, taste, and texture. The findings of our review suggest that PMF itself would be beneficial as a bacteria inactivation technique or could be readily combined with other suitable methods. Besides, we recommend conceivable paths to adopt this sustainable technique in the food industry. • Pulsed magnetic field as a nonthermal sterilization technology is presented. • PMF is an effective and efficient microorganism eliminating process. • PMF exerts sterilization ability by magnetoporation and electromagnetic effects. • Pulsed magnetic field sterilization technology can be applied in the food industry.

Effect of the Application of Cold Plasma Energy on the Inactivation of Microorganisms, Proteins, and Lipids Deterioration in Adobera Cheese

Cheeses are perishable foods that must fulfill sanitary and quality requirements according to the parameters established globally. Plasma as a nonthermal inactivation technique has been a current research topic for food preservation, so the objective of this work was to study the effect of plasma energy against microorganisms in Adobera cheese (traditional Mexican cheese) as well as evaluate the possible degradation of lipids and protein. 108 CFU/mL of Escherichia coli ATCC 25922, Salmonella ATCC13076, and Staphylococcus aureus ATCC 6538 were inoculated at 0.5 g of Adobera cheese and were subjected to an energy of 30 volts, in a dielectric barrier discharge reactor (DBDR) at intervals of times 1, 3, 5, 7, 10, and 15 min. A flow of a mixture of air and helium at 96% purity was used. The decimal reduction time (D) was determined, and the oxidation of proteins and lipids was analyzed after each treatment. The results showed an annihilating effect of plasma on the indicator bacteria under study, and a reduction of 5 logarithmic cycles was obtained. The maximum degree of lipid oxidation was 23 acid degree values (ADV) after 7 min of exposure to plasma. The oxidation of proteins showed a direct and proportional relationship between the formation of carbonyl groups with the percentage significant loss to the concentration of carbonyl groups with the concentration of protein oxidation, after 3 min of exposure to cold plasma levels of 82% and 99% oxidation of Adobera cheese protein and free casein, respectively. We conclude that the plasma energy applied to Adobera cheese is an effective treatment to inactivate bacteria. However, there is the possibility of causing changes in taste and odor, due to the release of fatty acids and the oxidation of proteins.

Non-thermal plasma inactivation of Salmonella Typhimurium on different matrices and the effect of selected food components on its bactericidal efficacy

Non-thermal plasma (NTP) is known as an effective source of a variety of reactive species generated in the gas phase. Nowadays, NTP is gaining increasing interest from the food industry as a microbial inactivation technique. In the present study the effect of inoculation method and matrix on inactivation of Salmonella Typhimurium was examined by treating spread plated agar (2.2 log CFU/sample inactivation by NTP), spot inoculated agar (1.9 log CFU inactivation), glass beads (1.3 log CFU inactivation) and peppercorn (0.2 log CFU inactivation). Furthermore, multiple agar matrices supplemented with low and high concentrations of a certain food component (casein, starch, sunflower oil, vitamin C, sodium pyruvate or grinded peppercorns) were inoculated and treated to determine the effect of those components on NTP efficiency. Although starch, vitamin C and sodium pyruvate had no significant influence on the inactivation degree, the presence of 10% casein (2.1 log CFU/sample less inactivation compared to tryptone soy agar (TSA)), 10% pepper (2.1 log CFU less inactivation) or 1% and 10% sunflower oil (1.6 and 2.1 log CFU less inactivation, respectively) in TSA demonstrated the protective effect of these substances for NTP treatment. These experiments led to the conclusion that low inactivation on produce seemed not to arise from the inoculation method nor from the shape of the produce, but is the result of the food matrix.

Inactivation of bacteria causing soft rot disease in fresh cut cabbage using slightly acidic electrolyzed water

Slightly acidic electrolyzed water (SAEW), an efficient non-thermal microbial inactivation technique, has been broadly applied to control food safety and quality. This study aimed to evaluate the bactericidal effects of SAEW treatments on fresh cut cabbage and to assess the optimal treatment conditions for inactivating Pectobacterium carotovorum subsp. carotovorum (PCC), which is among the most common causes of soft rot in cabbage. To this end, multivariate statistical analysis was performed using response surface methodology (RSM) based on the Box–Behnken design (BBD) technique. The optimal treatment condition for disinfection of PCC with SAEW treatment comprised 22.17 ppm of free available chlorine in the SAEW and an exposure time of 180 s at 10 °C. The optimized SAEW treatment was verified experimentally on fresh cabbage with an observed reduction value of 5.94 ± 0.07 log10 CFU/g, which was similar to the predicted reduction value (6.21 log10 CFU/mL) in the suspension test. Taken together, these results indicate that SAEW can efficiently inactivate PCC cells in fresh cut cabbage. Moreover, the response surface quadratic polynomial equation is applicable for predicting the effect of SAEW treatments on PCC contamination in fresh cabbage production, processing, and distribution.

Dielectric barrier discharge cold atmospheric plasma: Influence of processing parameters on microbial inactivation in meat and meat products.

Decontamination of meat is commonly practiced to get rid of or decrease the microbial presence on the meat surface. Dielectric barrier discharge cold atmospheric plasma (DBD-CAP) as innovative technology is a food microbial inactivation technique considered in high regard by food scientists and engineers in present times. However, cold atmospheric plasma application is at the experimental stage, due to lack of sufficient information on its mode of action in inactivating microbes, food shelf-life extensibility, whereas, the nutritional value of food is preserved. In this review, we have appraised recent work on DBD-CAP concerning the decontamination treatment of meat products, highlighting the processing value results on the efficacy of the DBD-CAP microbial inactivation technique. Also, the paper will review the configurations, proposed mechanisms, and chemistry of DBD-CAP. Satisfactory microbial inactivation was observed. In terms of DBD-CAP application on sensory evaluation, inferences from reviewed literature showed that DBD has no significant effect on meat color and tenderness, whereas in contrast, TBARS values of fresh and processed meat are affected. DBD seems economically efficient and environmentally sustainable.

Effects of Optogenetic Suppression of Cortical Input on Primate Thalamic Neuronal Activity during Goal-Directed Behavior.

The motor thalamus relays signals from subcortical structures to the motor cortical areas. Previous studies in songbirds and rodents suggest that cortical feedback inputs crucially contribute to the generation of movement-related activity in the motor thalamus. In primates, however, it remains uncertain whether the corticothalamic projections may play a role in shaping neuronal activity in the motor thalamus. Here, using an optogenetic inactivation technique with the viral vector system expressing halorhodopsin, we investigated the role of cortical input in modulating thalamic neuronal activity during goal-directed behavior. In particular, we assessed whether the suppression of signals originating from the supplementary eye field at the corticothalamic terminals could change the task-related neuronal modulation in the oculomotor thalamus in monkeys performing a self-initiated saccade task. We found that many thalamic neurons exhibited changes in their firing rates depending on saccade direction or task event, indicating that optical stimulation exerted task-specific effects on neuronal activity beyond the global changes in baseline activity. These results suggest that the corticothalamic projections might be actively involved in the signal processing necessary for goal-directed behavior. However, we also found that some thalamic neurons exhibited overall, non-task-specific changes in the firing rate during optical stimulation, even in control animals without vector injections. The stimulation effects in these animals started with longer latency, implying a possible thermal effect on neuronal activity. Thus, our results not only reveal the importance of direct cortical input in neuronal activity in the primate motor thalamus, but also provide useful information for future optogenetic studies.

Sulfenylome analysis of pathogen‐inactivated platelets reveals the presence of cysteine oxidation in integrin signaling pathway and cytoskeleton regulation

Unlabelled Box AbstractBackgroundCysteine‐containing protein modifications are involved in numerous biological processes such redox regulation or signal transduction. During the preparation and storage of platelet concentrates, cell functions and protein regulations are impacted. In spite of several proteomic investigations, the platelet sulfenylome, ie, the proteins containing cysteine residues (R‐SH) oxidized to sulfenic acid (R‐SOH), has not been characterized. MethodsA dimedone‐based sulfenic acid tagging and enrichment coupled to a mass spectrometry identification workflow was developed to identify and quantify the sulfenic acid‐containing proteins in platelet concentrates treated or not with an amotosalen/ultraviolet A (UVA) pathogen inactivation technique. ResultsOne hundred and seventy‐four sulfenylated proteins were identified belonging mainly to the integrin signal pathway and cytoskeletal regulation by Rho GTPase. The impact on pathogen inactivated platelet concentrates was weak compared to untreated ones where three sulfenylated proteins (myosin heavy chain 9, integrin βIII, and transgelin 2) were significantly affected by amotosalen/UVA treatment. Of particular interest, the reported oxidation of cysteine residues in integrin βIII is known to activate the receptor αIIbβIII. Following the pathogen inactivation, it might trigger the phosphorylation of p38MAPK and explain the lesions reported in the literature. Moreover, procaspase activating compound‐1 (PAC‐1) binding assays on platelet activation showed an increased response to adenosine diphosphate exacerbated by the tagging of proteins with dimedone. This result corroborates the hypothesis of an oxidation‐triggered activation of αIIbβIII by the pathogen inactivation treatment. ConclusionsThe present work completes missing information on the platelet proteome and provides new insights on the effect of pathogen inactivation linked to integrin signaling and cytoskeleton regulation.

Application of modified fluorophore-assisted light inactivation technique in nervous system cell and explant cultures

Methods of molecular targeting are powerful tools for functional genomics studies. To analyze the biological function of the molecule, acute and temporally restricted inactivation of the targeted molecule is critical. We developed a simple experimental method of protein disruption in living nervous systems. We employed a fluorophore-assisted light inactivation (FALI) technique that uses light irradiation to produce photogenerated singlet oxygen free radical damage that is directed at targeted proteins through chromophore-conjugated antibodies. In order to apply the FALI technique to culture systems over a long period of time, we established a simple and easy-to-use long-term FALI (SELT-FALI) by modifying the original FALI to utilize weak blue light. To address the efficacy of the SELT-FALI technique, we used Neuropilin-2 (Nrp2), a receptor for a repulsive axon guidance molecule of Semaphorin-3F (Sema3F) as a test target molecule. We examined the effect of SELT-FALI of Nrp2 by assessing specific Sema3F-Nrp2 binding in various culture systems. SELT-FALI of Nrp2 resulted in complete inhibition of Sema3F binding to Nrp2 expressed on COS7 cells. This FALI efficacy was dependent on irradiated light power. SELT-FALI of Nrp2 decreased Sema3F-induced growth cone collapse in mouse sympathetic ganglion culture, and also resulted in a significant loss of repulsive response toward Sema3F in a collagen gel 3D culture system. Furthermore, continuous FALI of Nrp2 for 24 hours in developing neural tissue resulted in a significant reduction of Sema3F binding to Nrp2 expressing lateral olfactory tract (LOT) in organotypic culture of mouse telencephalon without any detrimental effects on LOT development. Thus, the FALI technique can be used for protein disruption with temporal resolution. Finally, we applied the SELT-FALI technique for functional screening of key molecules in LOT development, which resulted in the discovery of a novel functional molecule that functions in LOT formation, and this molecule was termed the lateral olfactory tract usher substance (LOTUS). This methodology can be used for functional screening of key molecules in a variety of culture systems.

Preceding treatment of non-thermal plasma (NTP) assisted the bactericidal effect of ultrasound on Staphylococcus aureus

Ultrasound is a promising non-thermal inactivation technique. However, ultrasound treatment alone is not very effective. In this study, combined applications of ultrasound and non-thermal plasma (NTP) were assessed for their inactivation efficacy and the physiological change on Staphylococcus aureus cells. The lethal and sublethal injury induced by individual ultrasound, NTP, ultrasound-NTP (UP) and NTP-ultrasound treatments was determined by plate count method. Then, we applied fluorescent technology to demonstrate the physiological variations of S. aureus during various treatments. NTP exposure followed by ultrasound treatment exhibited the highest inactivation rate of S. aureus. Prior NTP helped to provide enough reactive oxygen species (ROS) dissolved in the medium, and the subsequent ultrasound assisted in the injection of ROS into S. aureus cells. This accelerated the reaction between ROS and intracellular biomolecules, which led to the rapid death of the microbes. On the contrary, S. aureus cells treated with ultrasound first were more likely to develop and enhance oxidative response, allowing S. aureus to resist toward the following NTP stressor. Therefore, the findings of this study may be used to the optimization of hurdle technologies of ultrasound and NTP in practice.

Aluminum plasmonic nanoshielding in ultraviolet inactivation of bacteria

Ultraviolet (UV) irradiation is an effective bacterial inactivation technique with broad applications in environmental disinfection. However, biomedical applications are limited due to the low selectivity, undesired inactivation of beneficial bacteria and damage of healthy tissue. New approaches are needed for the protection of biological cells from UV radiation for the development of controlled treatment and improved biosensors. Aluminum plasmonics offers attractive opportunities for the control of light-matter interactions in the UV range, which have not yet been explored in microbiology. Here, we investigate the effects of aluminum nanoparticles (Al NPs) prepared by sonication of aluminum foil on the UVC inactivation of E. coli bacteria and demonstrate a new radiation protection mechanism via plasmonic nanoshielding. We observe direct interaction of the bacterial cells with Al NPs and elucidate the nanoshielding mechanism via UV plasmonic resonance and nanotailing effects. Concentration and wavelength dependence studies reveal the role and range of control parameters for regulating the radiation dosage to achieve effective UVC protection. Our results provide a step towards developing improved radiation-based bacterial treatments.

Auditory cue absence as a conditioned stimulus for delay eyeblink conditioning.

The present experiment was designed to determine if the absence of an auditory cue (i.e., a "tone-off" cue) would be an effective conditioned stimulus (CS) for delay eyeblink conditioning and to test if the medial geniculate nucleus (MGN) is part of the sensory pathway for tone-off conditioning. Rats were given paired or unpaired delay eyeblink conditioning to examine if responding to a tone-off CS was due to an associative process. An inactivation technique was performed on a separate group of rats to determine if the MGN is needed to express tone-off conditioning. The results showed that rats given paired conditioning acquired robust conditioned eyeblink responses (CRs) compared with rats given unpaired conditioning and that expression of tone-off elicited CRs was impaired when the MGN was inactivated. The findings suggest that tone-on and tone-off eyeblink conditioning may share a common neural pathway. (PsycINFO Database Record

Micro-CALI to Study Localized Roles of the Semaphorin Signaling Component CRMP in Axon Growth.

Elucidating the local function of proteins is essential for understanding not only the individual proteins but also the organization of the cell or even tissue as a whole. However, until now, few attempts have been made to understand local proteins function in cells because of a lack of acute inactivation technique of local proteins with high versatility. Here we describe the application of the chromophore-assisted light inactivation (CALI) method to elucidate the role of the semaphorin signaling component CRMP located within the growth cone area in axon growth and growth cone turning.

Daun02 Inactivation of Behaviorally Activated Fos‐Expressing Neuronal Ensembles

Learned associations about salient experiences (e.g., drug exposure, stress) and their associated environmental stimuli are mediated by a minority of sparsely distributed, behaviorally activated neurons coined 'neuronal ensembles.' For many years, it was not known whether these neuronal ensembles played causal roles in mediating learned behaviors. However, in the last several years the 'Daun02 inactivation technique' in Fos-lacZ transgenic rats has proved very useful in establishing causal links between neuronal ensembles that express the activity-regulated protein Fos and learned behaviors. Fos-expressing neurons in these rats also express the bacterial protein β-galactosidase (β-gal) in strongly activated neurons. When the prodrug Daun02 is injected into the brains of these rats 90min after a behavior (e.g., drug-seeking) or cue exposure, then Daun02 is converted into daunorubicin by β-gal, which selectively inactivates Fos- and β-gal-expressing neurons that were activated 90min before the Daun02 injection. This unit presents protocols for breeding the Fos-lacZ rats and conducting appropriate Daun02 inactivation experiments. © 2016 by John Wiley & Sons, Inc.

Intranasal vaccination with γ-irradiated Streptococcus pneumoniae whole-cell vaccine provides serotype-independent protection mediated by B-cells and innate IL-17 responses.

Generating a pneumococcal vaccine that is serotype independent and cost effective remains a global challenge. γ-Irradiation has been used widely to sterilize biological products. It can also be utilized as an inactivation technique to generate whole-cell bacterial and viral vaccines with minimal impact on pathogen structure and antigenic determinants. In the present study, we utilized γ-irradiation to inactivate an un-encapsulated Streptococcus pneumoniae strain Rx1 with an unmarked deletion of the autolysin gene lytA and with the pneumolysin gene ply replaced with an allele encoding a non-toxic pneumolysoid (PdT) (designated γ-PN vaccine). Intranasal vaccination of C57BL/6 mice with γ-PN was shown to elicit serotype-independent protection in lethal challenge models of pneumococcal pneumonia and sepsis. Vaccine efficacy was shown to be reliant on B-cells and interleukin (IL)-17A responses. Interestingly, immunization promoted IL-17 production by innate cells not T helper 17 (Th17) cells. These data are the first to report the development of a non-adjuvanted intranasal γ-irradiated pneumococcal vaccine that generates effective serotype-independent protection, which is mediated by both humoral and innate IL-17 responses.

Photothermal inactivation of heat-resistant bacteria on nanoporous gold disk arrays

A rapid photothermal bacterial inactivation technique has been developed by irradiating near-infrared (NIR) light onto bacterial cells (Escherichia coli, Bacillus subtilis, Exiguobacterium sp. AT1B) deposited on surfaces coated with a dense, random array of nanoporous gold disks (NPGDs). With the use of cell viability tests and SEM imaging results, the complete inactivation of the pathogenic and heat-resistant bacterial model strains is confirmed within ~25 s of irradiation of the NPGD substrate. In addition to irradiation control experiments to prove the efficacy of the bacterial inactivation, thermographic imaging showed an immediate averaged temperature rise above 200 °C within the irradiation spot of the NPGD substrate. The light-gated photothermal effects on the NPGD substrate offers potential applications for antimicrobial and nanotherapeutic devices due to strong light absorption in the tissue optical window, i.e., the NIR wavelengths, and robust morphological structure that can withstand high instantaneous thermal shocks.

Micro-Inactivation of Coliforms by Low-Temperature and Atmospheric-Pressure Plasma Irradiation

In this study, we report on the inactivation technique to apply the oral surgery by micro low-temperature and atmospheric-pressure plasma irradiation utilizing a capillary nozzle. Emission spectrum of the micro-plasma showed OH and O radical, which were affected inactivation of coliform. Vibration temperature of the micro-plasma with 7998 K was calculated from peak-intensity at emission due to N22nd positive system. Inactivation region was larger than plasma irradiation spot, and it was increasing with plasma irradiation time.

Dissecting and engineering of the TetR family regulator SACE_7301 for enhanced erythromycin production in Saccharopolyspora erythraea.

BackgroundSaccharopolyspora erythraea was extensively utilized for the industrial-scale production of erythromycin A (Er-A), a macrolide antibiotic commonly used in human medicine. Yet, S. erythraea lacks regulatory genes in the erythromycin biosynthetic gene (ery) cluster, hampering efforts to enhance Er-A production via the engineering of regulatory genes.ResultsBy the chromosome gene inactivation technique based on homologous recombination with linearized DNA fragments, we have inactivated a number of candidate TetR family transcriptional regulators (TFRs) and identified one TFR (SACE_7301) positively controlling erythromycin biosynthesis in S. erythraea A226. qRT-PCR and EMSA analyses demonstrated that SACE_7301 activated the transcription of erythromycin biosynthetic gene eryAI and the resistance gene ermE by interacting with their promoter regions with low affinities, similar to BldD (SACE_2077) previously identified to regulate erythromycin biosynthesis and morphological differentiation. Therefore, we designed a strategy for overexpressing SACE_7301 with 1 to 3 extra copies under the control of PermE* in A226. Following up-regulated transcriptional expression of SACE_7301, eryAI and ermE, the SACE_7301-overexpressed strains all increased Er-A production over A226 proportional to the number of copies. Likewise, when SACE_7301 was overexpressed in an industrial S. erythraea WB strain, Er-A yields of the mutants WB/7301, WB/2×7301 and WB/3×7301 were respectively increased by 17%, 29% and 42% relative to that of WB. In a 5 L fermentor, Er-A accumulation increased to 4,230 mg/L with the highest-yield strain WB/3×7301, an approximately 27% production improvement over WB (3,322 mg/L).ConclusionsWe have identified and characterized a TFR, SACE_7301, in S. erythraea that positively regulated erythromycin biosynthesis, and overexpression of SACE_7301 in wild-type and industrial S. erythraea strains enhanced Er-A yields. This study markedly improves our understanding of the unusual regulatory mechanism of erythromycin biosynthesis, and provides a novel strategy towards Er-A overproduction by engineering transcriptional regulators of S. erythraea.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-014-0158-4) contains supplementary material, which is available to authorized users.