Integration Host Factor (IHF) binds to the promoter region of the phtD operon involved in phaseolotoxin synthesis in P. syringae pv. phaseolicola NPS3121

<p>Abstract</p> <p>Background</p> <p><it>Pseudomonas syringae </it>pv. phaseolicola, the causal agent of halo blight disease in beans, produces a toxin known as phaseolotoxin, in whose synthesis participate a group of genes organized within the genome in a region known as the "Pht cluster". This region, which is thought to have been acquired by horizontal gene transfer, includes 5 transcriptional units, two monocistronic (<it>argK, phtL</it>) and three polycistronic (<it>phtA, phtD, phtM</it>), whose expression is temperature dependent. So far, the regulatory mechanisms involved in phaseolotoxin synthesis have not been elucidated and the only well-established fact is the requirement of low temperatures for its synthesis. In this work, we searched for regulatory proteins that could be involved in phaseolotoxin synthesis, focusing on the regulation of the <it>phtD </it>operon.</p> <p>Results</p> <p>In this study we identified the global regulator IHF (Integration Host Factor), which binds to the promoter region of the <it>phtD </it>operon, exerting a negative effect on the expression of this operon. This is the first regulatory protein identified as part of the phaseolotoxin synthesis system. Our findings suggest that the Pht cluster was similarly regulated in the ancestral cluster by IHF or similar protein, and integrated into the global regulatory mechanism of <it>P. syringae </it>pv. phaseolicola, after the horizontal gene transfer event by using the host IHF protein.</p> <p>Conclusion</p> <p>This study identifies the IHF protein as one element involved in the regulation of phaseolotoxin synthesis in <it>P. syringae </it>pv. phaseolicola NPS3121 and provides new insights into the regulatory mechanisms involved in phaseolotoxin production.</p

Determinación de la actividad insecticida de Heliopsis Longipes A. Gray Blake, una planta endémica del estado de Guanajuato

Los mosquitos constituyen la principal vía para la transmisión del paludismo que afecta la salud humana y ocasiona un impacto negativo en la economía dado que los tratamientos son costosos e imposibilitan laboralmente a los individuos enfermos. Una de las estrategias para minimizar la transmisión de esta enfermedad lo constituye el uso de insecticidas químicos los cuales a pesar de ser excelentes métodos para disminuir la población de insectos, ocasionan efectos adversos en el ser humano y en el medio ambiente. Por esta razón es necesario explorar otras alternativas, de bajo costo y amigables con el medio ambiente, como el uso de extractos de plantas, los cuales son fuente potencial de insecticidas de origen natural. En este trabajo se determinó el efecto insecticida de una planta endémica del estado de Guanajuato, Heliopsis longipes A. Gray Blake contra el mosquito Anopheles albimanus, vector del paludismo. Los resultados obtenidos demuestran que H. longipes A. Gray Blake tiene potencial insecticida para ser utilizada como una alternativa en el control el insecto-vector del paludismo

Determination of insecticidal activity of Heliopsis longipes A. Gray Blake, an endemic plant of Guanajuato state

Mosquitoes are involved in transmission of infectious diseases like malaria which affect human health, causing economic losses due to expensive treatments and job incapacity of patients. Strategies to minimize transmission of this disease are the employ of chemical insecticides that are excellent methods to reduce insect populations; however it causes deleterious effects on human health and environmental damage. Therefore is necessary to explore harmless alternatives, such as plant extracts which are potential source of natural insecticides. In this work we evaluated insecticidal properties of Heliopsis longipes A. Gray Blake against third instar larvae of Anopheles albimanus, malaria vector. Results showed that H.longipes A. Gray Blake has insecticide properties to control insect involved in malaria transmission

Metagenome-assembled bacterial genomes recovered from the datasets of Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae)

Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), also known as the fall armyworm, is an economically important and widespread polyphagous pest. Microorganisms associated to this insect during life cycle play important ecological roles. We report 3 metagenome-assembled bacterial genomes reconstructed from a metagenome dataset obtained from S. frugiperda larvae F3 3rd-instar reared using artificial diet under laboratory conditions. Genome data for Enterococcus casseliflavus indicated a genome length of 3,659,8333 bp and GC content of 42.54%. Genome data for E. mundtii indicated a genome length of 2,921,701 bp and GC content of 38.37%. Finally, genome data for Lactiplantibacillus plantarum indicated a genome length of 3,298,601 bp, GC content of 44.31%. Genome analysis allowed us to identify genus-specific protein families (PLFams), transporters and antibiotic resistance-related genes among others. DNA sequences were deposited in National Center for Biotechnology Information (https://www.ncbi.nlm.nih.gov/) as Bioproject accession PRJNA899064

Detection of <i>Bacillus cereus sensu lato</i> Isolates Posing Potential Health Risks in Mexican Chili Powder

The potential presence of spore-forming bacteria related to the Bacillus cereus group in Mexican chili powder elaborated from Capsicum annuum L. is of commercial and clinical interest, because chili powder is an essential spice in the Mexican diet and in diets around the globe. To facilitate detection and isolation of members of this group of spore-forming bacteria from Mexican chili powder samples, we identified colonies that grew on agar medium selective for Bacillus cereus sensu lato, supplemented with polymyxin B (10 µg/mL) and ampicillin (10 to 100 µg/mL). The presumptive B. cereus (s.l.) isolates were tested using a tRNACys-PCR-based approach and the results identified species related phylogenetically to B. cereus, B. thuringiensis, and B. toyonensis. Their toxigenic potential was assessed by serological tests to detect enterotoxins (Nhe and Hbl) and by PCR targeting the hemolysin BL (hbl) component C (hblC) and non-hemolytic enterotoxin component A (nheA). The antibiotic profiles of the isolates showed a high resistance to β-lactams (100% of the isolates), trimethoprim-sulfamethoxazole (100%), tetracycline (90%), erythromycin (77%), clindamycin (74%), and chloramphenicol (42%). Our results indicate the presence of B. cereus s.l. with toxigenic characteristics in Mexican chili powder. Because of the potential for these organisms to cause disease through their production of various toxins, and resistance to antibiotics, we recommend that a microbiological risk assessment must be considered in the Mexican regulatory requirements

Insights into the Bacterial Diversity and Detection of Opportunistic Pathogens in Mexican Chili Powder

Chili powder is the most frequently consumed spice in Mexican diets. Thus, the dissemination of microorganisms associated with chili powder derived from Capsicum annuum L. is significant during microbial quality analysis, with special attention on detection of potential pathogens. The results presented here describe the initial characterization of bacterial community structure in commercial chili powder samples. Our results demonstrate that, within the domain Bacteria, the most abundant family was Bacillaceae, with a relative abundance of 99% in 71.4% of chili powder samples, while 28.6% of samples showed an average relative abundance of 60% for the Enterobacteriaceae family. Bacterial load for aerobic mesophilic bacteria (AMB) ranged from 104 to 106 cfu/g, while for sporulated mesophilic bacteria (SMB), the count ranged from 102 to 105 cfu/g. Bacillus cereus sensu lato (s.l.) was observed at ca. &#706;600 cfu/g, while the count for Enterobacteriaceae ranged from 103 to 106 cfu/g, Escherichia coli and Salmonella were not detected. Fungal and yeast counts ranged from 102 to 105 cfu/g. Further analysis of the opportunistic pathogens isolated, such as B. cereus s.l. and Kosakonia cowanii, using antibiotic-resistance profiles and toxinogenic characteristics, revealed the presence of extended-spectrum &beta;-lactamases (ESBLs) and Metallo-&beta;-lactamases (MBLs) in these organisms. These results extend our knowledge of bacterial diversity and the presence of opportunistic pathogens associated with Mexican chili powder and highlight the potential health risks posed by its use through the spread of antibiotic-resistance and the production of various toxins. Our findings may be useful in developing procedures for microbial control during chili powder production

Characterization of Endophytic Bacteria Isolated from Typha latifolia and Their Effect in Plants Exposed to Either Pb or Cd

Plant-associated bacteria in heavy-metal-contaminated environments could be a biotechnological tool to improve plant growth. The present work aimed to isolate lead- and cadmium-tolerant endophytic bacteria from the roots of Typha latifolia growing in a site contaminated with these heavy metals. Endophytic bacteria were characterized according to Pb and Cd tolerance, plant-growth-promoting rhizobacteria activities, and their effect on T. latifolia seedlings exposed and non-exposed to Pb and Cd. Pb-tolerant isolates were identified as Pseudomonas azotoformans JEP3, P. fluorescens JEP8, and P. gessardii JEP33, while Cd-tolerant bacteria were identified as P. veronii JEC8, JEC9, and JEC11. They all exert biochemical activities, including indole acetic acid synthesis, siderophore production, and phosphate solubilization. Plant&ndash;bacteria interaction assays showed that P. azotoformans JEP3, P. fluorescens JEP8, P. gessardii JEP33, and P. veronii JEC8, JEC9, JEC11 promote the growth of T. latifolia seedlings by increasing the root and shoot length, while in plants exposed to either 5 mg/L of Pb or 10 mg/L of Cd, all bacterial isolates increased the shoot length and the number of roots per plant, suggesting that they are plant-growth-promoting rhizobacteria that could contribute to T. latifolia adaptation to the heavy metal polluted site

Enhanced Cd-Accumulation in Typha latifolia by Interaction with Pseudomonas rhodesiae GRC140 under Axenic Hydroponic Conditions

The Typha genus comprises plant species extensively studied for phytoremediation processes. Recently, Pseudomonas rhodesiae GRC140, an IAA-producing bacterium, was isolated from Typha latifolia roots. This bacterium stimulates the emergence of lateral roots of Arabidopsis thaliana in the presence and absence of cadmium. However, the bacterial influence on cadmium accumulation by the plant has not been determined. Moreover, the P. rhodesiae GRC140 effect in Cd phytoextraction by T. latifolia remains poorly understood. In this work, an axenic hydroponic culture of T. latifolia was established. The plants were used to evaluate the effects of cadmium stress in axenic plants and determine the effects of P. rhodesiae GRC140 and exogenous indole acetic acid (IAA) on Cd tolerance and Cd uptake by T. latifolia. Biomass production, total chlorophyll content, root electrolyte leakage, catalase activity, total glutathione, and Cd content were determined. The results showed that Cd reduces shoot biomass and increases total glutathione and Cd content in a dose-dependent manner in root tissues. Furthermore, P. rhodesiae GRC140 increased Cd translocation to the shoots, while IAA increased the Cd accumulation in plant roots, indicating that both treatments increase Cd removal by T. latifolia plants. These results indicate that axenic plants in hydroponic systems are adequate to evaluate the Cd effects in plants and suggest that T. latifolia phytoextraction abilities could be improved by P. rhodesiae GRC140 and exogenous IAA application