Parasitic Bacteria Research Articles

Infectious disease: what's new in 2022

While recent epidemics have generated particular interest in viral infections, it should be noted that diagnostic, prophylactic or therapeutic innovations concerning other pathogens are not lacking. New vaccines (malaria, shingles) but new viruses (Lengya, child hepatitis), new therapeutic options against disabling parasitic diseases and bacteria becoming more and more resistant, including tuberculosis, shortening of treatment durations (tuberculosis, endocarditis), new diagnostic tests (borreliosis) are, among others, some notable recent innovations.

Evolutionary Challenges to Humanity Caused by Uncontrolled Carbon Emissions: The Stockholm Paradigm.

This review paper discusses the Stockholm Paradigm (SP) as a theoretical framework and practical computational instrument for studying and assessing the risk of emerging infectious diseases (EIDs) as a result of climate change. The SP resolves the long-standing parasite paradox and explains how carbon emissions in the atmosphere increase parasites' generalization and intensify host switches from animals to humans. The SP argues that the growing rate of novel EID occurrence caused by mutated zoonotic pathogens is related to the following factors brought together as a unified issue of humanity: (a) carbon emissions and consequent climate change; (b) resettlement/migration of people with hyper-urbanization; (c) overpopulation; and (d) human-induced distortion of the biosphere. The SP demonstrates that, in an evolutionary way, humans now play a role migratory birds once played in spreading parasite pathogens between the three Earth megabiotopes (northern coniferous forest belt; tropical/equatorial rainforest areas; and hot/cold deserts), i.e., the role of "super-spreaders" of parasitic viruses, bacteria, fungi and protozoa. This makes humans extremely vulnerable to the EID threat. The SP sees the +1.0-+1.2 °C limit as the optimal target for the slow, yet feasible curbing of the EID hazard to public health (150-200 years). Reaching merely the +2.0 °C level will obviously be an EID catastrophe, as it may cause two or three pandemics each year. We think it useful and advisable to include the SP-based research in the scientific repository of the Intergovernmental Panel on Climate Change, since EID appearance and spread are indirect but extremely dangerous consequences of climate change.

Reconstitution of a minimal motility system based on Spiroplasma swimming by two bacterial actins in a synthetic minimal bacterium.

Motility is one of the most important features of life, but its evolutionary origin remains unknown. In this study, we focused on Spiroplasma, commensal, or parasitic bacteria. They swim by switching the helicity of a ribbon-like cytoskeleton that comprises six proteins, each of which evolved from a nucleosidase and bacterial actin called MreB. We expressed these proteins in a synthetic, nonmotile minimal bacterium, JCVI-syn3B, whose reduced genome was computer-designed and chemically synthesized. The synthetic bacterium exhibited swimming motility with features characteristic of Spiroplasma swimming. Moreover, combinations of Spiroplasma MreB4-MreB5 and MreB1-MreB5 produced a helical cell shape and swimming. These results suggest that the swimming originated from the differentiation and coupling of bacterial actins, and we obtained a minimal system for motility of the synthetic bacterium.

A green and environmental sustainable approach to synthesis the Mn oxide nanomaterial from Punica granatum leaf extracts and its in vitro biological applications.

Pathogenic fungal infections in fruit cause economic losses and have deleterious effects on human health globally. Despite the low pH and high water contents of vegetables and fresh, ripened fruits, they are prone to fungal and bacterial diseases. The ever-increasing resistance of phytopathogens toward pesticides, fungicides and bactericides has resulted in substantial threats to plant growth and production in recent years. However, plant-mediated nanoparticles are useful tools for combating parasitic fungi and bacteria. Herein, we synthesized biogenic manganese oxide nanoparticles (MnONPs) from an extract of Punica granatum (P. granatum), and these nanoparticles showed significant antifungal and antibacterial activities. The production of MnONPs from plant extracts was confirmed by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and UV visible spectroscopy (UV). The surface morphology and shape of the nanoparticles were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Using a detached fruit method, the MnONPs were shown to exhibit significant antimicrobial activities against two bacterial strains, E. coli and S. aureus, and against the fungal species P. digitatum. The results revealed that the MnONPs had a minimum antimicrobial activity at 25µg/mL and a maximum antimicrobial activity at 100µg/mL against bacterial strains in lemon (citrus). Furthermore, the MnONPs exhibited significant ROS scavenging activity. Finally, inconclusive results from the green-synthesized MnONPs magnified their significant synergetic effects on the shelf life of tomatoes (Lycopercicum esculantum) and indicated that they could be used to counteract the phytopathological effects of postharvest fungal diseases in fruits and vegetables. Overall, this method of MnONPs synthesis is inexpensive, rapid and ecofriendly. MnONPs can be used as potential antimicrobial agents against different microbial species.

Microbial community composition in the rhizosphere of Pteris vittata and its effects on arsenic phytoremediation under a natural arsenic contamination gradient.

Arsenic contamination causes numerous health problems for humans and wildlife via bioaccumulation in the food chain. Phytoremediation of arsenic-contaminated soils with the model arsenic hyperaccumulator Pteris vittata provides a promising way to reduce the risk, in which the growth and arsenic absorption ability of plants and the biotransformation of soil arsenic may be greatly affected by rhizosphere microorganisms. However, the microbial community composition in the rhizosphere of P. vittata and its functional role in arsenic phytoremediation are still poorly understood. To bridge this knowledge gap, we carried out a field investigation and pot experiment to explore the composition and functional implications of microbial communities in the rhizosphere of four P. vittata populations with a natural arsenic contamination gradient. Arsenic pollution significantly reduced bacterial and fungal diversity in the rhizosphere of P. vittata (p < 0.05) and played an important role in shaping the microbial community structure. The suitability of soil microbes for the growth of P. vittata gradually decreased following increased soil arsenic levels, as indicated by the increased abundance of pathogenic fungi and parasitic bacteria and the decrease in symbiotic fungi. The analysis of arsenic-related functional gene abundance with AsChip revealed the gradual enrichment of the microbial genes involved in As(III) oxidation, As(V) reduction, and arsenic methylation and demethylation in the rhizosphere of P. vittata following increased arsenic levels (p < 0.05). The regulation of indigenous soil microbes through the field application of fungicide, but not bactericide, significantly reduced the remediation efficiency of P. vittata grown under an arsenic contamination gradient, indicating the important role of indigenous fungal groups in the remediation of arsenic-contaminated soil. This study has important implications for the functional role and application prospects of soil microorganisms in the phytoremediation of arsenic-polluted soil.

Changes in the Host Gut Microbiota during Parasitization by Parasitic Wasp Cotesia vestalis.

Simple SummaryCotesia vestalis is a larval endo-parasitoid of the diamondback moth (Plutella xylostella), which is a severe pest of cruciferous crops. The function of the gut microbiota of insects has been widely studied. However, it was unclear whether, and how, the gut microbiota of P. xylostella responds to its natural enemy, C. vestalis. In this study, a time-course experiment was performed to examine changes in the host–microbial community from the start of parasitization to the mature stage of the parasitoid larvae. Our results will provide a framework for studies of host-gut microbiota and parasitic wasp interactions.Parasites attack the host insects and possibly impact the host-gut microbiota, which leads to provision of a suitable host environment for parasites’ development. However, little is known about whether and how the parasitic wasp Cotesia vestalis alters the gut microbiota of the host Plutella xylostella. In this study, 16S rDNA microbial profiling, combined with a traditional isolation and culture method, were used to assess changes in the bacterial microbiome of parasitized and non-parasitized hosts at different developmental stages of C. vestalis larvae. Parasitization affected both the diversity and structure of the host-gut microbiota, with a significant reduction in richness on the sixth day post parasitization (6 DPP) and significant differences in bacterial structure between parasitized and non-parasitized hosts on the third day. The bacterial abundance of host-gut microbiota changed significantly as the parasitization progressed, resulting in alteration of potential functional contribution. Notably, the relative abundance of the predominant family Enterobacteriaceae was significantly decreased on the third day post-parasitization. In addition, the results of traditional isolation and culture of bacteria indicated differences in the bacterial composition between the three DPP and CK3 groups, as with 16S microbial profiling. These findings shed light on the interaction between a parasitic wasp and gut bacteria in the host insect during parasitization.

&lt;i&gt;In silico&lt;/i&gt; subtractive genomics approach characterizes a hypothetical protein (MG_476) from &lt;i&gt;microplasma genitalium&lt;/i&gt; G37

Background: Mycoplasma genitalium is a gram negative, parasitic pathogenic bacterium, usually transmitted sexually into human and frequently causing urethritis in men and women as well as cervicitis and pelvic inflammation in women. This is an extremely small self-replicating entity whose genome has been sequenced. This genome sequencing is advantageous in understanding pathogenesis and identifying therapeutic targets. In this study different bioinformatics tools and databases were adopted to analyze the functions of different hypothetical proteins from M. genitalium G37. Methodology: A total of 75 hypothetical proteins (HPs) were retrieved from KEGG database, while CDD-BLAST, Pfam, and InterProScan servers were used for conserved domains analysis. After that, those HPs were broadly analyzed for physicochemical properties, subcellular localization, GO annotation, and virulence factors. Results: Based on best score, hypothetical protein MG_476 was selected for homology modelling which produced a fairly good quality 3D model. The active site within MG_476 was predicted using CASTp server that helps to explore the surface features of the protein. Other approaches include the use of NetCTL, IEDB, Bcepred, and ABCpred servers to predict the location of B and T cell epitopes. Among the CD8+ T cell epitopes tested, ILQIIMFIL scored highest (0.23718) in terms of immunogenicity. Conclusion: Moreover, this analysis recommended MG_476 as a non-homologous protein and the data generated in this study may facilitate the experimental designing of novel drug and vaccines against M. genitalium.

Alfalfa Diseases and Control Methods

Alfalfa (Medicago sativa L.), which is one of the most cultivated plants among the forage crops in our country and other developed countries, and known as the queen of forage crops, has attracted attention in recent years on organic agricultural production and sustainability of agricultural lands. Many factors cause pathogenic effects in alfalfa. These are non-parasitic agents, parasitic disease agents fungi, bacteria, viruses, mycoplasma-like organisms, nematodes, and parasitic plants. Among them, fungi constitute an important group (Graham et al. 1979). The importance of disease factors that can occur in such a beneficial plant, the diagnosis of these factors, and the necessary management of them on time are of great value for obtaining quality products and for the country's economy.

Cell shape controls rheotaxis in small parasitic bacteria.

Mycoplasmas, a group of small parasitic bacteria, adhere to and move across host cell surfaces. The role of motility across host cell surfaces in pathogenesis remains unclear. Here, we used optical microscopy to visualize rheotactic behavior in three phylogenetically distant species of Mycoplasma using a microfluidic chamber that enabled the application of precisely controlled fluid flow. We show that directional movements against fluid flow occur synchronously with the polarized cell orienting itself to be parallel against the direction of flow. Analysis of depolarized cells revealed that morphology itself functions as a sensor to recognize rheological properties that mimic those found on host-cell surfaces. These results demonstrate the vital role of cell morphology and motility in responding to mechanical forces encountered in the native environment.

Bortezomib Eliminates Persistent Chlamydia trachomatis Infection through Rapid and Specific Host Cell Apoptosis.

Chlamydia trachomatis, a parasitic intracellular bacterium, is a major human pathogen that causes millions of trachoma, sexually transmitted infections, and pneumonia cases worldwide. Previously, peptidomimetic inhibitors consisting of a hydrophobic dipeptide derivative exhibited significant inhibitory effects against chlamydial growth. Based on this finding, this study showed that both bortezomib (BTZ) and ixazomib (IXA), anticancer drugs characterized by proteasome inhibitors, have intensive inhibitory activity against Chlamydia. Both BTZ and IXA consisted of hydrophobic dipeptide derivatives and strongly restricted the growth of Chlamydia (BTZ, IC50 = 24 nM). In contrast, no growth inhibitory effect was observed for other nonintracellular parasitic bacteria, such as Escherichia coli. BTZ and IXA appeared to inhibit chlamydial growth bacteriostatically via electron microscopy. Surprisingly, Chlamydia-infected cells that induced a persistent infection state were selectively eliminated by BTZ treatment, whereas uninfected cells survived. These results strongly suggested the potential of boron compounds based on hydrophobic dipeptides for treating chlamydial infections, including persistent infections, which may be useful for future therapeutic use in chlamydial infectious diseases.

Power‐assisted rotary cutter with negative pressure suction through small incision for axillary osmidrosis

The glandular fluid secreted by apocrine sweat glands is decomposed by parasitic bacteria on the skin surface and releases a bad smell called axillary osmidrosis. To evaluate the effect of power-assisted rotary cutter with negative pressure suction through small incision for axillary osmidrosis. From January 2017 to January 2022, 647 patients with axillary osmidrosis underwent power-assisted rotary cutter with negative pressure suction through small incision surgery to treat for axillary osmidrosis. The operation time (min), intraoperative bleeding (ml) and recovery time (days) were counted. Three months after operation, the amount of underarm sweat, the disappearance of underarm hair, the incidence of operation, the effective rate of operation, and the satisfaction of operation results were evaluated by questionnaire. There were no postoperative complications except five cases of mild axillary pigmentation after 3months. All patients evaluated good odor elimination. No patient was rated as average or poor. No recurrence. Power-assisted rotary cutter with negative pressure suction through small incision is an effective and ideal surgical method to reduce the complications and recurrence of axillary osmidrosis.

Anaemia in Lambs Caused by Mycoplasma ovis: Global and Australian Perspectives.

Simple SummaryMycoplasma ovis (formerly Eperythrozoon ovis) inhabits red blood cells and may cause their destruction, leading to anaemia, jaundice and death mainly in lambs, and condemnation of jaundiced carcases at abattoirs. Mycoplasmosis is spread during high-risk procedures that expose or share blood, especially when blood sucking flies and other insects are present on wounds that transfer infection. High-risk procedures include vaccination (re-use of needles), ear-tagging (ineffective disinfection), surgical castration and mulesing (in Australia), and potentially crutching and shearing, with outbreaks usually occurring up to 6 weeks later. Affected animals are weak, lagging in the ‘tail of the mob’ and collapsing when mustered. The investigation of other causes of anaemia and jaundice is required, particularly haemonchosis (Barbers pole worms) and malnutrition. The diagnosis involves the demonstration of M. ovis in blood smears and/or by PCR, although the absence of the parasite in smears from affected animals requires the examination of in-contact healthy animals. Treatment with antibiotics is ineffective. For its control, it is required that risky procedures are avoided during high insect activity and the yarding of stock within the next 6 weeks is minimised. Recent anecdotal observations suggest that improved farm practices, including fly control and pain/antiseptic wound dressing may potentially decrease M. ovis risk on some farms in some areas of Australia.Mycoplasma ovis (formerly Eperythrozoon ovis) is a haemotropic parasitic bacterium found within erythrocytes and distributed widely in global sheep and goat production regions. M. ovis is transmitted by biting flies and by contaminated instruments, causing morbidity and mortalities from anaemia, usually within 6 weeks following blood-exposure procedures, particularly vaccination, castration, ear tagging, mulesing, and occasionally crutching and shearing. Affected animals develop haemolytic anaemia and may have jaundice, causing abattoir condemnations. The typical history, clinical and pathological findings, display of M. ovis in blood smears and/or by PCR is diagnostic, although immune responses deplete M. ovis from smears; hence, in-contact healthy animals should be examined. Differential diagnoses include haemonchosis, fasciolosis, malnutrition (copper or vitamin B12 deficiency), and plant toxicities. M. ovis parasitaemia may persist, with recrudescence following stressful events, although most older sheep remain immune. Human infections have been reported. Inadequate socioeconomic data present difficulties in assessing the impact of M. ovis on production and as antimicrobial therapy is ineffective, its control requires management practices that minimize the impact of invasive procedures in periods when risks of M. ovis transmission are more likely. Although considered an emerging pathogen, recent improvements in welfare attitudes and husbandry practices on Australian sheep farms may potentially limit the transmission of M. ovis.

Progress of regulatory T cells in the regulation of anti-tuberculosis immunity

Mycobacterium tuberculosis (MTB), as an intracellular parasitic bacterium, invades the human body mainly through droplets, which can lead to multiple organ infection, causing the body to produce T cell-dominated immunity to tuberculosis (TB). Regulatory T cells (Tregs), as a class of T lymphocyte subsets that negatively regulate the immune response of the body, play an important role in regulating immune balance in host anti-tuberculosis immunity. A large number of studies have shown that MTB-specific Tregs affects the occurrence and development of tuberculosis and the efficacy of the vaccine. Therefore, elucidating the role and regulatory mechanism underlying anti-MTB immune response of MTB-specific Tregs will help to further understanding of the decrease of host anti-MTB immune cell function, and provide a basis for the study of immunotherapy of TB. This paper briefly introduces the subtypes and functions of Tregs, and systematically reviews the research progress of Tregs in many fields of TB.

Phylogenomic analysis of the diversity of graspetides and proteins involved in their biosynthesis

BackgroundBacteria and archaea produce an enormous diversity of modified peptides that are involved in various forms of inter-microbial conflicts or communication. A vast class of such peptides are Ribosomally synthesized, Postranslationally modified Peptides (RiPPs), and a major group of RiPPs are graspetides, so named after ATP-grasp ligases that catalyze the formation of lactam and lactone linkages in these peptides. The diversity of graspetides, the multiple proteins encoded in the respective Biosynthetic Gene Clusters (BGCs) and their evolution have not been studied in full detail. In this work, we attempt a comprehensive analysis of the graspetide-encoding BGCs and report a variety of novel graspetide groups as well as ancillary proteins implicated in graspetide biosynthesis and expression.ResultsWe compiled a comprehensive, manually curated set of graspetides that includes 174 families including 115 new families with distinct patterns of amino acids implicated in macrocyclization and further modification, roughly tripling the known graspetide diversity. We derived signature motifs for the leader regions of graspetide precursors that could be used to facilitate graspetide prediction. Graspetide biosynthetic gene clusters and specific precursors were identified in bacterial divisions not previously known to encode RiPPs, in particular, the parasitic and symbiotic bacteria of the Candidate phyla radiation. We identified Bacteroides-specific biosynthetic gene clusters (BGC) that include remarkable diversity of graspetides encoded in the same loci which predicted to be modified by the same ATP-grasp ligase. We studied in details evolution of recently characterized chryseoviridin BGCs and showed that duplication and horizonal gene exchange both contribute to the diversification of the graspetides during evolution.ConclusionsWe demonstrate previously unsuspected diversity of graspetide sequences, even those associated with closely related ATP-grasp enzymes. Several previously unnoticed families of proteins associated with graspetide biosynthetic gene clusters are identified. The results of this work substantially expand the known diversity of RiPPs and can be harnessed to further advance approaches for their identification.

Lysine Acylation Modification Landscape of Brucella abortus Proteome and its Virulent Proteins.

The myriad of posttranslational modifications (PTMs) of proteins that occur in all living cells are crucial to all kinds of biological processes. Brucella is an intracellular parasitic bacterium that can cause chronic diseases in both humans and livestock. To reveal the relationship between PTMs and the virulence and survival of Brucella, we described the first comprehensive multiple PTM-omics atlas of B. abortus 2308. Five PTMs involving lysine, namely 2-hydroxyisobutyrylation, succinylation, crotonylation, acetylation, and malonylation were identified. Nearly 2,000 modified proteins were observed, and these proteins took part in many biological processes, with a variety of molecular functions. In addition, we detected many significant virulence factors of Brucella among the modified proteins. 10 of the 15 T4SS effector proteins were detected with one or more PTMs. Moreover, abundant PTMs were detected in other typical virulence factors. Considering the role of PTMs in various biological processes of Brucella virulence and survival, we propose that the virulence of Brucella is associated with the PTMs of proteins. Taken together, this study provides the first global survey of PTMs in Brucella. This is a prospective starting point for further functional analysis of PTMs during the survival of Brucella in hosts, interpretation of the function of Brucella proteins, and elucidation of the pathogenic mechanism of Brucella.

Long-term grazing of Cervus elaphus kansuensis restrains expansion of Salix cupularis shrubs in the Eastern Qilian Mountains

Alpine shrubland not only has significant ecological function and ecological value, but also is a grazing land for Tibetan livestock and a habitat for wild animals. However, the grazing livestock on a long-term scale has caused severe shrubization of the alpine shrubland. How to control the shrubization of grassland is very important. Therefore, the purpose was to explore the effects of long-term grazing and utilization patterns of different livestock on alpine shrubland. In this study, a collective pasture with basically the same grazing history, intensity and vegetation type was enclosed into two sample plots to graze by Cervus elaphus kansuensis (CEK), and mixed grazing by Bos grunniens (yak) and Ovis aries (Tibetan sheep) (YTS) from 1983 to 2019 respectively, and it provides an vital scientific basis for promoting the balanced development of grass and livestock and maintaining ecological balance. The results showed that, in 2018 and 2019, compared with grazing YTS, the biomass of the Salix cupularis in grazing CEK plot was 55.20% and 56.63% lower, the cluster height was 68.36% and 68.36% lower, the crown width was 75.34% and 76.00% lower, the coverage was 80.00% and 78.00% lower, and the difference was significant ( P < 0.05). The cluster height of Spiraea alpina was also 47.17% and 44.38% lower; The Shannon-Wiener index, Simpson index and evenness index of the shrub communities in the CEK plot were significantly higher than YTS ( P < 0.05); The leaf carbon storage of Salix cupularis in CEK was 26.48% and 18.44% lower, and the root carbon storage was 48.88% and 49.15% higher respectively. The contents of soil organic matter, total phosphorus, total potassium, available nitrogen and available potassium in CEK were higher than those in YTS. In 2018, the soil respiration rate among CEK shrubs was significantly lower than that of YTS by 46.81%; The diversity and wealth of the bacterial community between shrubs, and the wealth index of the fungal community under shrubs in the CEK plot were all lower than those of YTS plot. The relative abundance of saprophytic fungi and bacterial metabolism between and under shrubs in grazing CEK plot were higher than that of YTS, while the relative abundance of arbuscular mycorrhizal fungi, animal parasitic bacteria and human-related infectious disease bacteria were lower than YTS. Therefore, moderate long-time grazing of Cervus elaphus kansuensis can effectively inhibit the spread of alpine shrubs, facilitate the growth of herbaceous plants and achieve the balanced development of grass and livestock. It provides a strong support for the rational utilization and management of alpine shrubs.

The VirB System Plays a Crucial Role in Brucella Intracellular Infection

Brucellosis is a highly prevalent zoonotic disease caused by Brucella. Brucella spp. are gram-negative facultative intracellular parasitic bacteria. Its intracellular survival and replication depend on a functional virB system, an operon encoded by VirB1–VirB12. Type IV secretion system (T4SS) encoded by the virB operon is an important virulence factor of Brucella. It can subvert cellular pathway and induce host immune response by secreting effectors, which promotes Brucella replication in host cells and induce persistent infection. Therefore, this paper summarizes the function and significance of the VirB system, focusing on the structure of the VirB system where VirB T4SS mediates biogenesis of the endoplasmic reticulum (ER)-derived replicative Brucella-containing vacuole (rBCV), the effectors of T4SS and the cellular pathways it subverts, which will help better understand the pathogenic mechanism of Brucella and provide new ideas for clinical vaccine research and development.

Analysis of Ficus hirta Fig Endosymbionts Diversity and Species Composition

Endosymbionts living in plants and insects are pervasive. Ficus (Moraceae) has very special inflorescences (which we also call figs) enclosed like an urn, and such inflorescence is usually parasitized by fig wasps. Ficus breeds fig wasp larvae in its figs and adult fig wasps pollinate for Ficus, Ficus and its obligated pollinator formed fig-fig wasp mutualism. Previous studies have found that this confined environment in figs may have provided protection for fig wasps and that this has left some imprints on the genome of fig wasps during the coevolution history of figs and fig wasps. Research on the diversity of both bacteria and fungi in figs are fewer. Our study explored the diversity of endosymbionts in Ficus hirta figs. We utilized high-throughput sequencing and biological database to identify the specific microorganism in figs, then conducted microorganism communities’ diversity analysis and function annotation analysis. As a result, we identified the dominant endosymbionts in figs, mainly some insect internal parasitic bacteria and fungi, plant pathogen, endophytes, and saprotroph. Then we also found bacteria in Ficus hirta figs were more diversified than fungi, and bacteria communities in female figs and functional male figs were different. These findings may give us more insight into the coevolution and interaction among endosymbiont, fig, and fig wasp.

A Novel LysR Family Factor STM0859 is Associated with The Responses of Salmonella Typhimurium to Environmental Stress and Biofilm Formation.

Salmonella enterica subsp. enterica serovar Typhimurium (ST) is an intracellularly parasitic bacterium. This zoonotic pathogen causes food poisoning and thus imposes a severe threat to food safety. Here, to understand the regulatory roles of the novel transcription factor STM0859 on the response of ST to environmental stress and biofilm formation, the STM0859 gene-deficient strain and the complementation strain ΔSTM0859/STM0859 were generated, respectively. Then, its capacity of responding to environmental stresses and biofilm (BF) formation ability under different stresses, including acid, alkali, high salt, cholate, and oxidative stresses was tested. We further analyzed the interaction between the STM0859 protein and the promoter of the acid stress response-related gene rcsB by performing an electrophoresis mobility shift assay (EMSA). The results showed that acid resistance and BF formation capacities of ST-ΔSTM0859 strain were significantly weaker, as compared with those of Salmonella Typhimurium SL1344 (ST-SL1344) wild strain (p < 0.01). Quantitative qRT-PCR analysis showed that the expression levels of acid stress and BF formation-related genes, rcsB and rpoS, of ST-ΔSTM0859 strain were significantly reduced at the transcription levels, while the transcription levels of these genes were fully restored in complementation strain ST-ΔSTM0859/STM0859. The results of EMSA showed that STM0859 was capable of binding the promoter DNA fragments of the rcsB gene, suggesting that STM0859 can promote the transcription of the rcsB gene through interaction with its promoter, thereby exerting an indirectly regulatory role on the adaptive responses to acid stress and BF formation of ST. This study provided new insights into the regulatory mechanisms of the LysR family factors on the tolerances of ST under adverse environmental stresses.

Degradation without ubiquitination: new function of a parasite effector

Like many other pathogens, the obligate parasitic bacteria phytoplasmas reply on secreted effectors to cause diseases in their plant hosts. Huang et al. revealed that a phytoplasma effector degrades plant proteins independent of ubiquitination. Bypassing this degradation step makes Arabidopsis thaliana plants resistant to this parasite effector.