MuscleX: data analysis software for fiber diffraction patterns from muscle.

MuscleX is an integrated, open-source computer software suite for data reduction of X-ray fiber diffraction patterns from striated muscle and other fibrous systems. It is written in Python and runs on Linux, Microsoft Windows or macOS. Most modules can be run either from a graphical user interface or in a `headless mode' from the command line, suitable for incorporation into beamline control systems. Here, we provide an overview of the general structure of the MuscleX software package and describe the specific features of the individual modules as well as examples of applications.

Preparation, purification, and biochemical of fat-degrading bacterial enzymes from pig carcass compost and its application.

BACKGROUND: A lot of kitchen waste oil is produced every day worldwide, leading to serious environmental pollution. As one of the environmental protection methods, microorganisms are widely used treating of various wastes. Lipase, as one of the cleaning agents can effectively degrade kitchen waste oil. The composting process of pig carcasses produces many lipase producing microorganisms, rendering compost products an excellent source for isolating lipase producing microorganisms. To our knowledge, there are no reports isolating of lipase producing strains from the high temperature phase of pig carcass compost. METHODOLOGY: Lipase producing strains were isolated using a triglyceride medium and identified by 16S rRNA gene sequencing. The optimal fermentation conditions for maximum lipase yield were gradually optimized by single-factor tests. The extracellular lipase was purified by ammonium sulfate precipitation and Sephadex G-75 gel isolation chromatography. Amino acid sequence analysis, structure prediction, and molecular docking of the purified protein were performed. The pure lipase's enzymatic properties and application potential were evaluated by characterizing its biochemical properties. RESULTS: In this study, a lipase producing strain of Bacillus sp. ZF2 was isolated from pig carcass compost products, the optimal fermentation conditions of lipase: sucrose 3 g/L, ammonium sulfate 7 g/L, Mn2+ 1.0 mmol/L, initial pH 6, inoculum 5%, temperature 25 ℃, and fermentation time 48 h. After purification, the specific activity of the purified lipase reached 317.59 U/mg, a 9.78-fold improvement. Lipase had the highest similarity to the GH family 46 chitosanase and molecular docking showed that lipase binds to fat via two hydrogen bonds at Gln146 (A) and Glu203 (A). Under different conditions (temperature, metal ions, organic solvents, and surfactants), lipase can maintain enzymatic activity. Under different types of kitchen oils, lipase has low activity only for 'chicken oil', in treating other substrates, the enzyme activity can exceed 50%. CONCLUSIONS: This study reveals the potential of lipase for waste oil removal, and future research will be devoted to the application of lipase.

Development of a microbial protease for composting swine carcasses, optimization of its production and elucidation of its catalytic hydrolysis mechanism.

BACKGROUND: Dead swine carcass composting is an excellent method for harmless treatment and resource utilization of swine carcass. However, poor biodegradation ability of traditional composting results in poor harmless treatment effect. Researches report that the biodegradation ability of composting can be improved by inoculation with enzyme-producing microorganisms or by inoculation with enzyme preparations. At present, the researches on improving the efficiency of dead swine carcass composting by inoculating enzyme-producing microorganisms have been reported. However, no work has been reported on the development of enzyme preparations for dead swine carcass composting. METHODOLOGY: The protease-producing strain was isolated by casein medium, and was identified by 16 S rRNA gene sequencing. The optimal fermentation conditions for maximum protease production were gradually optimized by single factor test. The extracellular protease was purified by ammonium sulfate precipitation and Sephadex G-75 gel exclusion chromatography. The potential for composting applications of the purified protease was evaluated by characterization of its biochemical properties. And based on amino acid sequence analysis, molecular docking and inhibition test, the catalytic hydrolysis mechanism of the purified protease was elucidated. RESULTS: In this study, a microbial protease was developed for swine carcass composting. A protease-producing strain DB1 was isolated from swine carcass compositing and identified as Serratia marcescen. Optimum fermentation conditions for maximum protease production were 5 g/L glucose, 5 g/L urea, 1.5 mmol/L Mg2+, initial pH-value 8, inoculation amount 5%, incubation temperature 30 °C and 60 h of fermentation time. The specific activity of purified protease reached 1982.77 U/mg, and molecular weight of the purified protease was 110 kDa. Optimum pH and temperature of the purified protease were 8 and 50 °C, respectively, and it had good stability at high temperature and in alkaline environments. The purified protease was a Ser/Glu/Asp triad serine protease which catalyzed substrate hydrolysis by Glu, Arg, Ser, Asp and Tyr active residues. CONCLUSIONS: In general, the microbial protease developed in this study was suitable for industrial production and has the potential to enhance composting at thermophilic stage. Moreover, the catalytic hydrolysis mechanism of the protease was further analyzed in this study.

Hydrogen peroxide plus ascorbic acid enhanced organic matter deconstructions and composting performances via changing microbial communities.

This work aims to investigate the influence of hydrogen peroxide (H2O2) and ascorbic acid (ASCA) on the physicochemical characteristics, organic matter (OM) deconstructions, humification degree and succession of bacterial communities for co-composting of bagasse pith and dairy manure. The results indicated that H2O2 and ASCA accelerated the degradation of lignocellulose, improved the transformation of dissolved organic matter (DOM), and enhanced the content of humic substance (HS) and the degree of its aromatization. The bacterial communities were significantly changed in the presence of additives, in which the relative abundances of Firmicutes and Actinobacteria significantly increased. Redundancy analysis (RDA) indicated that the degradation of OM and lignocellulose more influenced the bacterial community compositions. Conclusively, adding H2O2 and ASCA accelerated lignocellulose degradation efficiency, and improved the composting process, which provided an optimized method to dispose of lignocellulose wastes and livestock manure.

[Advances in Polymer Hydrophilic Lubricating Coatings for Medical Catheters].

Polymer hydrophilic lubricating coatings for medical catheters refer to highly hydrophilic coating films fixed on the surface of catheters with binding force, which can reduce the surface friction with human tissues during the use of interventional catheters, improve the patient comfort of and effectively reduce the incidence of infection. Based on the development process of medical catheter coating, this review summarizes recent advances in the field of polymer hydrophilic lubricating coatings for medical catheters from types of hydrophilic coating polymer, development of coating technology and establishment of coating performance evaluation method. Main problems in this field are analyzed and development trends in the future are prospected.

Overproduction of a Dominant Mutant of the Conserved Era GTPase Inhibits Cell Division in Escherichia coli.

Cell growth and division are coordinated, ensuring homeostasis under any given growth condition, with division occurring as cell mass doubles. The signals and controlling circuit(s) between growth and division are not well understood; however, it is known in Escherichia coli that the essential GTPase Era, which is growth rate regulated, coordinates the two functions and may be a checkpoint regulator of both. We have isolated a mutant of Era that separates its effect on growth and division. When overproduced, the mutant protein Era647 is dominant to wild-type Era and blocks division, causing cells to filament. Multicopy suppressors that prevent the filamentation phenotype of Era647 either increase the expression of FtsZ or decrease the expression of the Era647 protein. Excess Era647 induces complete delocalization of Z rings, providing an explanation for why Era647 induces filamentation, but this effect is probably not due to direct interaction between Era647 and FtsZ. The hypermorphic ftsZ* allele at the native locus can suppress the effects of Era647 overproduction, indicating that extra FtsZ is not required for the suppression, but another hypermorphic allele that accelerates cell division through periplasmic signaling, ftsL*, cannot. Together, these results suggest that Era647 blocks cell division by destabilizing the Z ring.IMPORTANCE All cells need to coordinate their growth and division, and small GTPases that are conserved throughout life play a key role in this regulation. One of these, Era, provides an essential function in the assembly of the 30S ribosomal subunit in Escherichia coli, but its role in regulating E. coli cell division is much less well understood. Here, we characterize a novel dominant negative mutant of Era (Era647) that uncouples these two activities when overproduced; it inhibits cell division by disrupting assembly of the Z ring, without significantly affecting ribosome production. The unique properties of this mutant should help to elucidate how Era regulates cell division and coordinates this process with ribosome biogenesis.

Positive and negative selection using the tetA-sacB cassette: recombineering and P1 transduction in Escherichia coli.

The two-step process of selection and counter-selection is a standard way to enable genetic modification and engineering of bacterial genomes using homologous recombination methods. The tetA and sacB genes are contained in a DNA cassette and confer a novel dual counter-selection system. Expression of tetA confers bacterial resistance to tetracycline (Tc(R)) and also causes sensitivity to the lipophillic chelator fusaric acid; sacB causes sensitivity to sucrose. These two genes are introduced as a joint DNA cassette into Escherichia coli by selection for Tc(R). A medium containing both fusaric acid and sucrose has been developed, in which, coexpression of tetA-sacB is orders of magnitude more sensitive as a counter-selection agent than either gene alone. In conjunction with the homologous recombination methods of recombineering and P1 transduction, this powerful system has been used to select changes in the bacterial genome that cannot be directly detected by other counter-selection systems.

[Simulation of TDLAS direct absorption based on HITRAN database].

Simulating of the direct absorption TDLAS spectrum can help to comprehend the process of the absorbing and understand the influence on the absorption signal with each physical parameter. Firstly, the basic theory and algorithm of direct absorption TDLAS is studied and analyzed thoroughly, through giving the expressions and calculating steps of parameters based on Lambert-Beer's law, such as line intensity, absorption cross sections, concentration, line shape and gas total partition functions. The process of direct absorption TDLAS is simulated using MATLAB programs based on HITRAN spectra database, with which the absorptions under a certain temperature, pressure, concentration and other conditions were calculated, Water vapor is selected as the target gas, the absorptions of which under every line shapes were simulated. The results were compared with that of the commercial simulation software, Hitran-PC, which showed that, the deviation under Lorentz line shape is less than 0. 5%, and that under Gauss line shape is less than 2. 5%, while under Voigt line shape it is less than 1%. It verified that the algorithm and results of this work are correct and accurate. The absorption of H2O in v2 + v3 band under different pressure and temperature is also simulated. In low pressure range, the Doppler broadening dominant, so the line width changes little with varied.pressure, while the line peak increases with rising pressure. In high pressure range, the collision broadening dominant, so the line width changes wider with increasing pressure, while the line peak approaches to a constant value with rising pressure. And finally, the temperature correction curve in atmosphere detection is also given. The results of this work offer the reference and instruction for the application of TDLAS direct absorption.

Bacterial DNA polymerases participate in oligonucleotide recombination.

Synthetic single-strand oligonucleotides (oligos) with homology to genomic DNA have proved to be highly effective for constructing designed mutations in targeted genomes, a process referred to as recombineering. The cellular functions important for this type of homologous recombination have yet to be determined. Towards this end, we have identified Escherichia coli functions that process the recombining oligo and affect bacteriophage λ Red-mediated oligo recombination. To determine the nature of oligo processing during recombination, each oligo contained multiple nucleotide changes: a single base change allowing recombinant selection, and silent changes serving as genetic markers to determine the extent of oligo processing during the recombination. Such oligos were often not incorporated into the host chromosome intact; many were partially degraded in the process of recombination. The position and number of these silent nucleotide changes within the oligo strongly affect both oligo processing and recombination frequency. Exonucleases, especially those associated with DNA Polymerases I and III, affect inheritance of the silent nucleotide changes in the oligos. We demonstrate for the first time that the major DNA polymerases (Pol I and Pol III) and DNA ligase are directly involved with oligo recombination.

Cellulosimicrobium sp. Strain L1: A Study on the Optimization of the Conditions and Performance of a Combined Biological Trickling Filter for Hydrogen Sulfide Degradation.

Sulfide is a toxic and hazardous substance in the agricultural environment, which can cause damage to humans and livestock when exposed to large amounts of air. In this study, we performed one-factor optimization of the culture conditions and culture fractions of the Cellulosimicrobium sp. strain L1 and combined it with a biological trickling filter cell for the degradation of hydrogen sulfide for 24 consecutive days. The degradation effect of strain L1 and the biological trickling filter (BTF) on hydrogen sulfide was investigated, and the changes in intermediate products in the degradation process were briefly analyzed. The results showed that strain L1 had the highest conversion efficiency when incubated with 3 g/L sucrose as the carbon source and 1 g/L NH4Cl as the nitrogen source at a temperature of 35 °C, an initial pH of 5, and a NaCl concentration of 1%. The concentration of thiosulfate increased and then decreased during the degradation process, and the concentration of sulfate increased continuously. When strain L1 was applied to the biological trickling filter, it could degrade 359.53 mg/m3 of H2S. This study provides a deeper understanding of sulfide degradation in biological trickling filters and helps promote the development of desulfurization technology and the treatment of malodorous gasses produced by the accumulation of large quantities of livestock manure.

Periplaneta americana extract promotes infectious diabetic ulcers wound healing by downregulation of LINC01133/SLAMF9.

Wound healing in diabetic ulcers remains a significant clinical challenge, primarily due to bacterial infection and impaired angiogenesis. Periplaneta americana extract (PAE) has been widely used to treat diabetic wounds, yet its underlying mechanisms are not fully understood. This study aimed to elucidate these mechanisms by analyzing long non-coding RNA (lncRNA) expressions in the wound tissues from diabetic anal fistula patients treated with or without PAE, using high-throughput sequencing. Peripheral blood monocytes from patients were differentiated into M0 macrophages with human macrophage colony-stimulating factor (hM-CSF) and subsequently polarized into M1 macrophages with lipopolysaccharide. The results indicated that LINC01133 and SLAMF9 were downregulated in wound tissues of patients treated with PAE. Furthermore, PAE suppressed M1 macrophage polarization and enhanced human umbilical vein endothelial cell (HUVEC) proliferation, migration, and angiogenesis. These effects were diminished when LINC01133 or SLAMF9 were overexpressed. Mechanistically, LINC01133 was shown to upregulate SLAMF9 through interaction with ELAVL1. Overexpression of SLAMF9 reversed the effects of LINC01133 silencing on macrophage polarization and HUVEC functions. In conclusion, PAE facilitates the healing of infected diabetic ulcers by downregulating the LINC01133/SLAMF9 pathway.

Stability and gene strand bias of lambda prophages and chromosome organization in Escherichia coli.

Temperate phage-mediated horizontal gene transfer is a potent driver of genetic diversity in the evolution of bacteria. Most lambdoid prophages in Escherichia coli are integrated into the chromosome with the same orientation with respect to the direction of chromosomal replication, and their location on the chromosome is far from homogeneous. To better understand these features, we studied the interplay between lysogenic and lytic states of phage lambda in both native and inverted integration orientations at the wild-type integration site as well as at other sites on the bacterial chromosome. Measurements of free phage released by spontaneous induction showed that the stability of lysogenic states is affected by location and orientation along the chromosome, with stronger effects near the origin of replication. Competition experiments and range expansions between lysogenic strains with opposite orientations and insertion loci indicated that there are no major differences in growth. Moreover, measurements of the level of transcriptional bursts of the cI gene coding for the lambda phage repressor using single-molecule fluorescence in situ hybridization resulted in similar levels of transcription for both orientations and prophage location. We postulate that the preference for a given orientation and location is a result of a balance between the maintenance of lysogeny and the ability to lyse.IMPORTANCEThe integration of genetic material of temperate bacterial viruses (phages) into the chromosomes of bacteria is a potent evolutionary force, allowing bacteria to acquire in one stroke new traits and restructure the information in their chromosomes. Puzzlingly, this genetic material is preferentially integrated in a particular orientation and at non-random sites on the bacterial chromosome. The work described here reveals that the interplay between the maintenance of the stability of the integrated phage, its ability to excise, and its localization along the chromosome plays a key role in setting chromosomal organization in Escherichia coli.

Synergistic promotion of nitrogen vacancies and single atomic dopants on Pt/C3N4 for photocatalytic hydrogen evolution.

C3N4 is widely applied in the synthesis of single-atom catalysts. However, understanding on the active site and the reaction mechanism is not fully in consensus. Especially, bare studies have considered the coordination environment of the single-atomic dopant and the effect of nitrogen vacancy on C3N4. In this study, we found that the presence of nitrogen vacancies promotes the activation of water and reduces the activation energy barrier for hydrogen generation. The results show that a synergistic effect between single-atom Pt and nitrogen vacancies enables the catalyst to achieve a superior hydrogen production rate of 3,890 µmol/g/h, which is 16.8 times higher than that of pristine C3N4. Moreover, the catalyst is also applicable for photocatalytic hydrogen production from seawater without significantly decreased hydrogen production rate. This study paves the way for the rational design and optimization of next-generation photocatalysts for sustainable energy applications, particularly in solar-driven hydrogen production.

The hidden costs of emotional labor on withdrawal behavior: the mediating role of emotional exhaustion, and the moderating effect of mindfulness.

BACKGROUND: Employees' withdrawal behavior concerns organization leaders and policymakers in many countries. However, the specific mechanism which emotional labor affects withdrawal behavior has yet to be thoroughly discussed. There needs to be systematic research on how different emotional labor strategies affect work withdrawal, whether directly or through individual perception, and how to respond. METHODS: A total of 286 hotel and catering service employees participated in our study. A series of hierarchical moderated regression analyses were performed to test the hypothesis. RESULTS: The results indicated that surface acting positively affected withdrawal behavior, while deep acting had a negative effect. Emotional exhaustion mediated in this relationship of surface acting with withdrawal behavior and deep acting with withdrawal behavior. Mindfulness showed moderation effects between emotional exhaustion and withdrawal behavior. CONCLUSIONS: Emotional labor and emotional exhaustion are significant in predicting employees' intentions to withdraw, given that emotional exhaustion partially mediates the effects of emotional labor on withdrawal behavior. Significantly, the relationship between emotional exhaustion and withdrawal behavior is weakened by mindfulness.

Recombineering: Genetic Engineering in Escherichia coli Using Homologous Recombination.

The bacterial chromosome and bacterial plasmids can be engineered in vivo by homologous recombination using either PCR products or synthetic double-stranded DNA (dsDNA) or single-stranded DNA as substrates. Multiple linear dsDNA molecules can be assembled into an intact plasmid. The technology of recombineering is possible because bacteriophage-encoded recombination proteins efficiently recombine sequences with homologies as short as 35 to 50 bases. Recombineering allows DNA sequences to be inserted or deleted without regard to the location of restriction sites and can also be used in combination with CRISPR/Cas targeting systems. © 2023 Wiley Periodicals LLC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA. Basic Protocol: Making electrocompetent cells and transforming with linear DNA Support Protocol 1: Selection/counter-selections for genome engineering Support Protocol 2: Creating and screening for oligo recombinants by PCR Support Protocol 3: Other methods of screening for unselected recombinants Support Protocol 4: Curing recombineering plasmids containing a temperature-sensitive replication function Support Protocol 5: Removal of the prophage by recombineering Alternate Protocol 1: Using CRISPR/Cas9 as a counter-selection following recombineering Alternate Protocol 2: Assembly of linear dsDNA fragments into functional plasmids Alternate Protocol 3: Retrieval of alleles onto a plasmid by gap repair Alternate Protocol 4: Modifying multicopy plasmids with recombineering Support Protocol 6: Screening for unselected plasmid recombinants Alternate Protocol 5: Recombineering with an intact λ prophage Alternate Protocol 6: Targeting an infecting λ phage with the defective prophage strains.

How Does Inclusive Leadership Curb Workers' Emotional Exhaustion? The Mediation of Caring Ethical Climate and Psychological Safety.

The COVID-19 pandemic has transformed the politics, economy, and society of the world, which has dealt the most severe blow to the hospitality industry. Meanwhile, the pandemic and government control policies have brought high psychological pressure to hospitality front-line employees, resulting in emotional exhaustion. As a part of burnout syndrome, emotional exhaustion poses a threat to employees' mental health, career sustainability, and well-being. Therefore, the purpose of this paper was to investigate the curb effectiveness of inclusive leadership on emotional exhaustion and to explore the mediation roles of ethical climate and psychological safety between them. Time-lagged data were collected from 65 teams and 358 hospitality front-line employees working in Chinese hotels in two stages with a one-month gap. This research verified that inclusive leadership has a negative impact on emotional exhaustion both indirectly through the mediation roles of ethical climate and psychological safety. And the ethical climate and psychological safety played partial mediation roles between inclusive leadership and emotional exhaustion. In theory, the findings explored the dual mediation mechanism of the inhibitory effect of inclusive leadership on emotional exhaustion. In practice, we provided the training and correct guidance to develop inclusive leadership for hotel enterprises and to resolve the emotional exhaustion of employees, which can enhance sustainability in careers.

Study on the air leakage characteristics of a goaf in a shallow coal seam and spontaneous combustion prevention and control strategies for residual coal.

Air leakage from surface mining-induced fissures can easily cause spontaneous combustion of residual coal in the goaf, which threatens the safe production of the underground working face. In order to study the air leakage law of the goaf under the surface air leakage and the prevention and control technology of spontaneous combustion of residual coal. Based on engineering data from the 6104 working face of the Chuancao Gedan coal mine, this study uses a combination of theoretical analyses, numerical simulations, and field observations to study the dynamic distribution characteristics of the air leakage velocity of surface mining-induced fissures in shallow coal seams, the distribution characteristics of relative pressure, the air leakage velocity, the air leakage flow field, the distribution ranges for the "three zones" of spontaneous combustion in the goaf, and a reasonable range for the pressurized ventilation of the working face. The results show that there is a quadratic relationship between the air leakage speed from the surface mining-induced fissures in shallow coal seams and the distance from the working face. The air leakage speed decreases as the distance from the working face increases, and the air leakage speed in the middle of the working face is slower than the air leakage on either side of the goaf. The pressure difference between the goaf and the surface mining-induced fissures is the root cause of air leakage into the goaf, and a change in the pressure difference has a significant impact on the air leakage flow field and the distributions of the "three zones" of spontaneous combustion in the goaf. When the pressure difference between the ground surface and the working face is maintained within the range of 200~-200 Pa, air leakage is effectively reduced, and the spontaneous combustion of residual coal is inhibited. The research results reveal the air leakage mechanism in the goaf of shallow coal seams and provide a reference for the prevention and control of spontaneous combustion of residual coal in the goaf.

Study on generation, migration and accumulation of CO in the mining goaf of shallow-buried close distance coal seam group.

There is complex air leakage in the mining of shallow buried close distance coal seam group, which affects the generation and migration of CO in the goaf, and easily leads to exceeding safety limits of CO in the return corner of the working face, which threatens the safety of underground production. To examine this problem, taking Lijiahao Coal Mine as an example, this study analyses the generation law of CO gas, the distribution law of overburden fractures, the characteristics of air leakage in the goaf, the sources of CO in the return corner, and the migration and accumulation law of CO in the goaf under multi-source air leakage in the mining of shallow buried close distance coal seam group through experiment tests, numerical simulations, observations and theoretical analyses. The results indicated that there is an exponential growth relationship between the CO generation rate and the coal temperature, and the critical temperature for rapid oxidation of coal samples is between 70 and 80 °C. The 31,115 working face has complicated air leakage from the working face and ground surface and the goaf of this coal seam. The surface air converges to the return corner through the mining fissure of overburden and 2-2 coal goaf, and the air leakage of the working face flows out from the return roadway through the goaf. The gas leakage in the overlying goaf and the oxidation of residual coal are the main sources of CO in the return corner. The CO generated during the coal mining process and the CO generated by the trackless rubber-tired vehicle operation will increase the CO concentration in the return corner to varying degrees. Under the effect of multi-source air leakage, CO from the overlying goaf and the residual coal in the goaf of this coal seam are migrated to the air return side of the goaf, resulting in the accumulation of CO in the return corner, and both of them have a linear positive correlation with the CO concentration in the return corner. The results of the study have scientific guidance for the control of air leakage and the prevention of CO excess in the goaf.

Homologs of the Escherichia coli F Element Protein TraR, Including Phage Lambda Orf73, Directly Reprogram Host Transcription.

Bacterial cells and their associated plasmids and bacteriophages encode numerous small proteins of unknown function. One example, the 73-amino-acid protein TraR, is encoded by the transfer operon of the conjugative F plasmid of Escherichia coli. TraR is a distant homolog of DksA, a protein found in almost all proteobacterial species that is required for ppGpp to regulate transcription during the stringent response. TraR and DksA increase or decrease transcription initiation depending on the kinetic features of the promoter by binding directly to RNA polymerase without binding to DNA. Unlike DksA, whose full activity requires ppGpp as a cofactor, TraR is fully active by itself and unaffected by ppGpp. TraR belongs to a family of divergent proteins encoded by proteobacterial bacteriophages and other mobile elements. Here, we experimentally addressed whether other members of the TraR family function like the F element-encoded TraR. Purified TraR and all 5 homologs that were examined bound to RNA polymerase, functioned at lower concentrations than DksA, and complemented a dksA-null strain for growth on minimal medium. One of the homologs, λ Orf73, encoded by bacteriophage lambda, was examined in greater detail. λ Orf73 slowed host growth and increased phage burst size. Mutational analysis suggested that λ Orf73 and TraR have a similar mechanism for inhibiting rRNA and r-protein promoters. We suggest that TraR and its homologs regulate host transcription to divert cellular resources to phage propagation or conjugation without induction of ppGpp and a stringent response. IMPORTANCE TraR is a distant homolog of the transcription factor DksA and the founding member of a large family of small proteins encoded by proteobacterial phages and conjugative plasmids. Reprogramming transcription during the stringent response requires the interaction of DksA not only with RNA polymerase but also with the stress-induced regulatory nucleotide ppGpp. We show here that five phage TraR homologs by themselves, without ppGpp, regulate transcription of host promoters, mimicking the effects of DksA and ppGpp together. During a stringent response, ppGpp independently binds directly to, and inhibits the activities of, many proteins in addition to RNA polymerase, including translation factors, enzymes needed for ribonucleotide biosynthesis, and other metabolic enzymes. Here, we suggest a physiological role for TraR-like proteins: bacteriophages utilize TraR homologs to reprogram host transcription in the absence of ppGpp induction and thus without inhibiting host enzymes needed for phage development.

Extraction, Purification, Characterization and Application in Livestock Wastewater of S Sulfur Convertase.

Sulfide is a toxic pollutant in the farming environment. Microbial removal of sulfide always faces various biochemical challenges, and the application of enzymes for agricultural environmental remediation has promising prospects. In this study, a strain of Cellulosimicrobium sp. was isolated: numbered strain L1. Strain L1 can transform S2-, extracellular enzymes play a major role in this process. Next, the extracellular enzyme was purified, and the molecular weight of the purified sulfur convertase was about 70 kDa. The sulfur convertase is an oxidase with thermal and storage stability, and the inhibitor and organic solvent have little effect on its activity. In livestock wastewater, the sulfur convertase can completely remove S2-. In summary, this study developed a sulfur convertase and provides a basis for the application in environmental remediation.