Effect of BvAgNP on growth, development, and glyoxalase gene expression analysis in Mammillaria bombycina and Selenicereus undatus.

BACKGROUND: Silver nanoparticles (AgNPs) have been used in plant tissue culture as growth stimulants, promoting bud initiation, germination, and rooting. In prior studies, AgNPs were synthesized and characterized by green synthesis using extracts from Beta vulgaris var. cicla (BvAgNP), and their functionality as seed disinfectant and antimicrobial was verified. In this study, we evaluated the effect of BvAgNP on the growth and development of Mammillaria bombycina and Selenicereus undatus in vitro, as well as the expression of glyoxalase genes. METHODS: Explants from M. bombycina and S. undatus in vitro were treated with 25, 50, and 100 mg/L of BvAgNP. After 90 days, morphological characteristics were evaluated, and the expression of glyoxalase genes was analyzed by qPCR. RESULTS: All treatments inhibited rooting for M. bombycina and no bud initiation was observed. S. undatus, showed a maximum response in rooting and bud generation at 25 mg/L of BvAgNP. Scanning electron microscopy (SEM) results exhibited a higher number of vacuoles in stem cells treated with BvAgNP compared to the control for both species. Expression of glyoxalase genes in M. bombycina increased in all treatments, whereas it decreased for S. undatus, however, increasing in roots. CONCLUSIONS: This study presents the effects of BvAgNP on the growth and development of M. bombycina and S. undatus, with the aim of proposing treatments that promote in vitro rooting and bud initiation.

Bacterial communities of the psyllid pest Bactericera cockerelli (Hemiptera: Triozidae) Central haplotype of tomato crops cultivated at different locations of Mexico.

Background: The psyllid, Bactericera cockerelli, is an insect vector of 'Candidatus Liberibacter' causing "Zebra chip" disease that affects potato and other Solanaceae crops worldwide. In the present study, we analyzed the bacterial communities associated with the insect vector Bactericera cockerelli central haplotype of tomato crop fields in four regions from Mexico. Methods: PCR was used to amplify the mitochondrial cytochrome oxidase I gene (mtCOI) and then analyze the single nucleotide polymorphisms (SNP) and phylogenetic analysis for haplotype identification of the isolated B. cockerelli. Moreover, we carried out the microbial diversity analysis of several B. cockerelli collected from four regions of Mexico through the NGS sequencing of 16S rRNA V3 region. Finally, Wolbachia was detected by the wsp gene PCR amplification, which is the B. cockerelli facultative symbiont. Also we were able to confirm the relationship with several Wolbachia strains by phylogenetic analysis. Results: Our results pointed that B. cockerelli collected in the four locations from Mexico (Central Mexico: Queretaro, and Northern Mexico: Sinaloa, Coahuila, and Nuevo Leon) were identified, such as the central haplotype. Analyses of the parameters of the composition, relative abundance, and diversity (Shannon index: 1.328 ± 0.472; Simpson index 0.582 ± 0.167), showing a notably relatively few microbial species in B. cockerelli. Analyses identified various facultative symbionts, particularly the Wolbachia (Rickettsiales: Anaplasmataceae) with a relative abundance higher. In contrast, the genera of Sodalis and 'Candidatus Carsonella' (Gammaproteobacteria: Oceanospirillales: Halomonadaceae) were identified with a relatively low abundance. On the other hand, the relative abundance for the genus 'Candidatus Liberibacter' was higher only for some of the locations analyzed. PCR amplification of a fragment of the gene encoding a surface protein (wsp) of Wolbachia and phylogenetic analysis corroborated the presence of this bacterium in the central haplotype. Beta-diversity analysis revealed that the presence of the genus 'Candidatus Liberibacter' influences the microbiota structure of this psyllid species. Conclusions: Our data support that the members with the highest representation in microbial community of B. cockerelli central haplotype, comprise their obligate symbiont, Carsonella, and facultative symbionts. We also found evidence that among the factors analyzed, the presence of the plant pathogen affects the structure and composition of the bacterial community associated with B. cockerelli.

Bacterial Strains from Saline Environment Modulate the Expression of Saline Stress-Responsive Genes in Pepper (Capsicum annuum).

Salinity stress is one of the most important problems in crop productivity. Plant growth-promoting bacteria (PGPB) can also confer stress tolerance in plants under saline soil conditions. In a previous work, it was reported that bacteria strains isolated from hypersaline sites mitigated salt stress in chili pepper (Capsicum annuum var. Caballero) plants and promoted plant growth in some cases. The aim of this study was to evaluate the modulation of gene expression in C. annuum plants by bacteria strains isolated from saline environments. Two bacteria strains from high salinity ponds in Guerrero Negro, BCS, Mexico (Bacillus sp. strain 32 and Staphylococcus sp. strain 155) and Azospirillum brasilense Cd (DSM 1843) were used. Significant improvement in fresh weight yield (stem (28%), root (128.9%), and leaves (20%)) was observed in plants inoculated with Bacillus sp. strain 32. qPCR analysis showed that both strains modulated the expression of stress-responsive genes (MYB, ETR1, JAR1, WRKY, and LOX2) as well as heat shock factors and protein genes (CahsfA2, CahsfA3, CahsfB3a, CaDNaJ02, and CaDNaJ04). Finally, the expression levels of genes related to early salt stress and ISR showed differences in plants with dual treatment (bacteria-inoculated and salt-stressed) compared to plants with simple salinity stress. This work confirmed the differential modification of the transcriptional levels of genes observed in plants inoculated with bacteria under salinity stress.

Habanero pepper (Capsicum chinense) adaptation to water-deficit stress in a protected agricultural system.

Drought is one of the major factors limiting global crop yield. In Mexico, agriculture is expected to be severely affected by drought. The Capsicum genus has several crop species of agricultural importance. In this work, we analysed the Capsicum chinense plant physiological responses and differentially expressed genes under water stress mainly focused on the responses elicited following recovery through repetitive stress. Plants were cultivated in an experimental block. Each block consisted of plants under water deficit and a control group without deficit. Morphometric and functional parameters, and the expression of genes related to resistance to abiotic stresses were measured. Morphological differences were observed. Plants subjected to water deficit showed impaired growth. Nonetheless, in the physiological parameters, no differences were observed between treatments. We selected abiotic stress-related genes that include heat-shock proteins (HSPs), heat-shock factors (HSFs), transcription factors related to abiotic stress (MYB, ETR1 , and WRKY ), and those associated with biotic and abiotic stress responses (Jar1 and Lox2 ). HSF, HSP, MYB72, ETR1, Jar1, WRKYa , and Lox2 genes were involved in the response to water-deficit stress in C. chinense plants. In conclusion, our work may improve our understanding of the morphological, physiological, and molecular mechanisms underlying hydric stress response in C. chinense .

De Novo Transcriptome of Mammillaria bombycina (Cactaceae) under In Vitro Conditions and Identification of Glyoxalase Genes.

Mammillaria bombycina is a cactus distributed in the central region of Mexico. Cactaceae have the particularity of surviving drought and high temperatures, which is why in vitro propagation studies have been carried out successfully to preserve this species and use it as a study model in cacti. In this contribution, a de novo transcriptome of M. bombycina was produced under in vitro conditions for the identification and expression of genes related to abiotic stress. Samples were sequenced using an Illumina platform, averaging 24 million clean readings. From assembly and annotation, 84,975 transcripts were generated, 55% of which were unigenes. Among these, the presence of 13 isoforms of genes belonging to glyoxalase I, II and III were identified. An analysis of the qRT-PCR expression of these genes was performed under in vitro and ex vitro conditions and dehydration at 6 and 24 h. The highest expression was observed under greenhouse conditions and dehydration at 24 h, according to the control. The de novo assembly of the M. bombycina transcriptome remains a study model for future work in cacti.

Actinobacillus pleuropneumoniae Surviving on Environmental Multi-Species Biofilms in Swine Farms.

Actinobacillus pleuropneumoniae is the etiologic agent of porcine contagious pleuropneumonia, an important respiratory disease for the pig industry. A. pleuropneumoniae has traditionally been considered an obligate pig pathogen. However, its presence in the environment is starting to be known. Here, we report the A. pleuropneumoniae surviving in biofilms in samples of drinking water of swine farms from Mexico. Fourteen farms were studied. Twenty drinking water samples were positive to A. pleuropneumoniae distributed on three different farms. The bacteria in the drinking water samples showed the ability to form biofilms in vitro. Likewise, A. pleuropneumoniae biofilm formation in situ was observed on farm drinkers, where the biofilm formation was in the presence of other bacteria such as Escherichia coli, Stenotrophomonas maltophilia, and Acinetobacter schindleri. Our data suggest that A. pleuropneumoniae can inhabit aquatic environments using multi-species biofilms as a strategy to survive outside of their host.

Characterization of microbial communities from rumen and large intestine of lactating creole goats grazing in arid plant communities.

Arid plant communities provide variable diets that can affect digestive microbial communities of free-foraging ruminants. Thus, we used next-generation sequencing of 16S and 18S rDNA to characterize microbial communities in the rumen (regurgitated digesta) and large intestine (faeces) and diet composition of lactating creole goats from five flocks grazing in native plant communities in the Sonoran Desert in the rainy season. The bacterial communities in the rumen and large intestine of the five flocks had similar alpha diversity (Chao1, Shannon, and Simpson indices). However, bacterial community compositions were different: a bacterial community dominated by Proteobacteria in the rumen transitioned to a community dominated by Firmicutes in the large intestine. Bacterial communities of rumen were similar across flocks; similarly occurred with large-intestine communities. Archaea had a minimum presence in the goat digestive tract. We detected phylum Basidiomycota, Ascomycota, and Apicomplexa as the main fungi and protozoa. Analyses suggested different diet compositions; forbs and grasses composed the bulk of plants in the rumen and forbs and shrubs in faeces. Therefore, lactating goats consuming different diets in the Sonoran Desert in the rainy season share a similar core bacterial community in the rumen and another in the large intestine and present low archaeal communities.

Biochemical characterization of LysVpKK5 endolysin from a marine vibriophage.

Endolysins have been proposed as a potential antibacterial alternative for aquaculture, especially against Vibrio; the bacterial-agents that most frequently cause disease. Although multiple marine vibriophages have been characterized to date, research on vibriophage endolysins is recent. In this study, biochemical characterization of LysVpKK5 endolysin encoded by Vibrio parahaemolyticus-infecting VpKK5 phage was performed. In silico analysis revealed that LysVpKK5 possesses a conserved amidase_2 domain with a zinc-binding motif of high structural similarity to T7 lysozyme (RMSD = 0.107 Å). Contrary to expectations, the activity was inhibited with Zn2+ and was improved with other divalent cations, especially Ca2+. It showed optimal muralytic activity at pH 10, and curiously, no lytic activity at pH ≤ 7 was recorded. As for the thermal stability test, the optimal activity was recorded at 30 °C; the higher residual activity was recorded at 4 °C, and was lost at ≥ 50 °C. On the other hand, increasing NaCl concentrations reduced the activity gradually; the optimal activity was recorded at 50 mM NaCl. On the other hand, the enzymatic activity at 0.5 M NaCl was approx 30% and of approx 50% in seawater. LysVpKK5 endolysin exhibited a higher activity on V. parahaemolyticus ATCC-17802 strain, in comparison with AHPND + strains.

Bacterial biofilm-derived antigens: a new strategy for vaccine development against infectious diseases.

INTRODUCTION: Microorganisms can develop into a social organization known as biofilms and these communities can be found in virtually all types of environment on earth. In biofilms, cells grow as multicellular communities held together by a self-produced extracellular matrix. Living within a biofilm allows for the emergence of specific properties for these cells that their planktonic counterparts do not have. Furthermore, biofilms are the cause of several infectious diseases and are frequently inhabited by multi-species. These interactions between microbial species are often critical for the biofilm process. Despite the importance of biofilms in disease, vaccine antigens are typically prepared from bacteria grown as planktonic cells under laboratory conditions. Vaccines based on planktonic bacteria may not provide optimal protection against biofilm-driven infections. AREAS COVERED: In this review, we will present an overview of biofilm formation, what controls this mode of growth, and recent vaccine development targeting biofilms. EXPERT OPINION: Previous and ongoing research provides evidence that vaccine formulation with antigens derived from biofilms is a promising approach to prevent infectious diseases and can enhance the protective efficacy of existing vaccines. Therefore, research focusing on the identification of biofilm-derived antigens merits further investigations.

Growth effects in oregano plants (Origanum vulgare L.) assessment through inoculation of bacteria isolated from crop fields located on desert soils.

Bacteria can establish beneficial interactions with plants by acting as growth promoters and enhancing stress tolerance during plant interactions. Likewise, bacteria can develop multispecies communities where multiple interactions are possible. In this work, we assessed the physiological effects of three bacteria isolated from an arid environment (Bacillus niacini, Bacillus megaterium, and Moraxella osloensis) applied as single species or as a consortium on oregano (Origanum vulgare L.) plants. Moreover, we assessed the quorum-sensing (QS) signaling activity to determine the molecular communication between plant-growth-promoting bacteria. The plant inoculation with B. megaterium showed a positive effect on morphometric and physiologic parameters. However, no synergistic effects were observed when a bacterial consortium was inoculated. Likewise, activation of QS signaling in biofilm assays was observed only for interspecies interaction within the Bacillus genus, not for either interaction with M. osloensis. These results suggest a neutral or antagonistic interaction for interspecific bacterial biofilm establishment, as well as for the interaction with oregano plants when bacteria were inoculated in a consortium. In conclusion, we were able to determine that the bacterial interactions are not always positive or synergistic, but they also might be neutral or antagonistic.

Molecular characterization and phylogenetic analysis of a Squash leaf curl virus isolate from Baja California Sur, Mexico.

BACKGROUND: The begomovirus, squash leaf curl virus (SLCuV) is one of the causal agents of squash leaf curl (SLC) disease, which is among the most destructive diseases of cucurbit crops in tropical, subtropical, and semiarid regions worldwide. This disease was originally reported in the American continent with subsequent spread to the Mediterranean basin. Up to now, SLCuV has only been detected by PCR in Mexico. This study provides the first complete sequence of a Mexican SLCuV isolate from Baja California Sur (BCS). In addition, the genome of the virus was characterized, establishing its phylogenetic relationship with other SLCuV isolates. METHODS: The full genome (DNA-A and DNA-B) was amplified by rolling circle amplification, cloned and sequenced and the open reading frames (ORF) were annotated. Virus identification was performed according to the International Committee on Taxonomy of Viruses (ICTV) criteria for begomovirus species demarcation. To infer evolutionary relationship with other SLCuV isolates, phylogenetic and recombination analyses were performed. RESULTS: The SLCuV-[MX-BCS-La Paz-16] genome (DNA-A and DNA-B) had 99% identity with SLCuV reference genomes. The phylogenetic analysis showed that SLCuV-[MX-BCS-La Paz-16] is closely related to SLCuV isolates from the Middle East (Egypt, Israel, Palestine and Lebanon). No evidence of interspecific recombination was determined and iterons were 100% identical in all isolates in the SLCuV clade. CONCLUSIONS: SLCuV-[MX-BCS-La Paz-16] showed low genetic variability in its genome, which could be due to a local adaptation process (isolate environment), suggesting that SLCuV isolates from the Middle East could have derived from the southwestern United States of America (USA) and northwestern Mexico.

Incorporation of Actinobacillus pleuropneumoniae in Preformed Biofilms by Escherichia coli Isolated From Drinking Water of Swine Farms.

Actinobacillus pleuropneumoniae, the etiological agent of porcine pleuropneumonia, represents one of the most important health problems in the swine industry worldwide and it is included in the porcine respiratory disease complex. One of the bacterial survival strategies is biofilm formation, which are bacterial communities embedded in an extracellular matrix that could be attached to a living or an inert surface. Until recently, A. pleuropneumoniae was considered to be an obligate pathogen. However, recent studies have shown that A. pleuropneumoniae is present in farm drinking water. In this study, the drinking water microbial communities of Aguascalientes (Mexico) swine farms were analyzed, where the most frequent isolated bacterium was Escherichia coli. Biofilm formation was tested in vitro; producing E. coli biofilms under optimal growth conditions; subsequently, A. pleuropneumoniae serotype 1 (strains 4074 and 719) was incorporated to these biofilms. Interaction between both bacteria was evidenced, producing an increase in biofilm formation. Extracellular matrix composition of two-species biofilms was also characterized using fluorescent markers and enzyme treatments. In conclusion, results confirm that A. pleuropneumoniae is capable of integrates into biofilms formed by environmental bacteria, indicative of a possible survival strategy in the environment and a mechanism for disease dispersion.

New trends in innovative vaccine development against Actinobacillus pleuropneumoniae.

Actinobacillus pleuropneumoniae is the etiological agent of porcine pleuropneumonia, a respiratory disease leading to severe economic losses in the swine industry. The most widely used commercial vaccines are bacterins comprising inactivated whole cells of A. pleuropneumoniae but these have only been partially effective in preventing disease. Innovative immuno-prophylactic preparations of A. pleuropneumoniae based on ApxI, ApxII, ApxIII, ApxIV toxins and outer membrane proteins, among others (i.e. RnhB, GalU, GalT, HflX, ComL, LolB, LppC), have high protective efficacy in mice and pigs. Some vaccine preparations have efficacy against homologous and heterologous A. pleuropneumoniae serovars, which constitute an important advance to control porcine pleuropneumonia. In this arena, subunit vaccines based on toxins are one of the most advanced and promising developments. Many research groups have focussed on the development of live attenuated vaccines comprising strains with inactivated Apx toxins and/or other virulence factors, their protective efficacy being determined in mouse and/or swine models. Other innovative approaches such as bacteria, yeast and plants as production and oral delivery platforms have been explored in animal models and the definitive host with encouraging results. In addition, further research into A. pleuropneumoniae-based DNA and nano-vaccines, as well as bioencapsulation of antigens in plants, is envisaged. Here, the recent findings and future trends in innovative vaccine development against A. pleuropneumoniae are reviewed and placed in perspective.

Identification of a 'Candidatus Phytoplasma hispanicum'-related strain, associated with yellows-type diseases, in smoke-tree sharpshooter (Homalodisca liturata Ball).

The 16SrXIII group from phytoplasma bacteria were identified in salivary glands from Homalodisca liturata, which were collected in El Comitán on the Baja California peninsula in Mexico. We were able to positively identify 15 16S rRNA gene sequences with the corresponding signature sequence of 'CandidatusPhytoplasma' (CAAGAYBATKATGTKTAGCYGGDCT) and in silico restriction fragment length polymorphism (RFLP) profiles (F value estimations) coupled with a phylogenetic analysis to confirm their relatedness to 'CandidatusPhytoplasma hispanicum', which in turn belongs to the 16SrXIII group. A restriction analysis was carried out with AluI and EcoRI to confirm that the five sequences belongs to subgroup D. The rest of the sequences did not exhibit any known RFLP profile related to a subgroup reported in the 16SrXIII group.

Actinobacillus pleuropneumoniae biofilms: Role in pathogenicity and potential impact for vaccination development.

Actinobacillus pleuropneumoniae is a Gram-negative bacterium that belongs to the family Pasteurellaceae. It is the causative agent of porcine pleuropneumonia, a highly contagious respiratory disease that is responsible for major economic losses in the global pork industry. The disease may present itself as a chronic or an acute infection characterized by severe pathology, including hemorrhage, fibrinous and necrotic lung lesions, and, in the worst cases, rapid death. A. pleuropneumoniae is transmitted via aerosol route, direct contact with infected pigs, and by the farm environment. Many virulence factors associated with this bacterium are well characterized. However, much less is known about the role of biofilm, a sessile mode of growth that may have a critical impact on A. pleuropneumoniae pathogenicity. Here we review the current knowledge on A. pleuropneumoniae biofilm, factors associated with biofilm formation and dispersion, and the impact of biofilm on the pathogenesis A. pleuropneumoniae. We also provide an overview of current vaccination strategies against A. pleuropneumoniae and consider the possible role of biofilms vaccines for controlling the disease.

Auxotrophic Actinobacillus pleurpneumoniae grows in multispecies biofilms without the need for nicotinamide-adenine dinucleotide (NAD) supplementation.

BACKGROUND: Actinobacillus pleuropneumoniae is the etiologic agent of porcine contagious pleuropneumonia, which causes important worldwide economic losses in the swine industry. Several respiratory tract infections are associated with biofilm formation, and A. pleuropneumoniae has the ability to form biofilms in vitro. Biofilms are structured communities of bacterial cells enclosed in a self-produced polymer matrix that are attached to an abiotic or biotic surface. Virtually all bacteria can grow as a biofilm, and multi-species biofilms are the most common form of microbial growth in nature. The goal of this study was to determine the ability of A. pleuropneumoniae to form multi-species biofilms with other bacteria frequently founded in pig farms, in the absence of pyridine compounds (nicotinamide mononucleotide [NMN], nicotinamide riboside [NR] or nicotinamide adenine dinucleotide [NAD]) that are essential for the growth of A. pleuropneumoniae. RESULTS: For the biofilm assay, strain 719, a field isolate of A. pleuropneumoniae serovar 1, was mixed with swine isolates of Streptococcus suis, Bordetella bronchiseptica, Pasteurella multocida, Staphylococcus aureus or Escherichia coli, and deposited in 96-well microtiter plates. Based on the CFU results, A. pleuropneumoniae was able to grow with every species tested in the absence of pyridine compounds in the culture media. Interestingly, A. pleuropneumoniae was also able to form strong biofilms when mixed with S. suis, B. bronchiseptica or S. aureus. In the presence of E. coli, A. pleuropneumoniae only formed a weak biofilm. The live and dead populations, and the matrix composition of multi-species biofilms were also characterized using fluorescent markers and enzyme treatments. The results indicated that poly-N-acetyl-glucosamine remains the primary component responsible for the biofilm structure. CONCLUSIONS: In conclusion, A. pleuropneumoniae apparently is able to satisfy the requirement of pyridine compounds through of other swine pathogens by cross-feeding, which enables A. pleuropneumoniae to grow and form multi-species biofilms.

Waterborne pathogens: detection methods and challenges.

Waterborne pathogens and related diseases are a major public health concern worldwide, not only by the morbidity and mortality that they cause, but by the high cost that represents their prevention and treatment. These diseases are directly related to environmental deterioration and pollution. Despite the continued efforts to maintain water safety, waterborne outbreaks are still reported globally. Proper assessment of pathogens on water and water quality monitoring are key factors for decision-making regarding water distribution systems' infrastructure, the choice of best water treatment and prevention waterborne outbreaks. Powerful, sensitive and reproducible diagnostic tools are developed to monitor pathogen contamination in water and be able to detect not only cultivable pathogens but also to detect the occurrence of viable but non-culturable microorganisms as well as the presence of pathogens on biofilms. Quantitative microbial risk assessment (QMRA) is a helpful tool to evaluate the scenarios for pathogen contamination that involve surveillance, detection methods, analysis and decision-making. This review aims to present a research outlook on waterborne outbreaks that have occurred in recent years. This review also focuses in the main molecular techniques for detection of waterborne pathogens and the use of QMRA approach to protect public health.

Detection of Actinobacillus pleuropneumoniae in drinking water from pig farms.

Actinobacillus pleuropneumoniae is the aetiological agent of porcine pleuropneumonia and is normally transmitted by aerosols and direct contact between animals. A. pleuropneumoniae has traditionally been considered an obligate pathogen of pigs and its presence in the environment has yet to be investigated. Here, the presence of A. pleuropneumoniae was detected in drinking water of pig farms in Mexico using a PCR specific for the RTX toxin gene, apxIV. The presence of A. pleuropneumoniae in farm drinking water was confirmed by indirect immunofluorescence using an A. pleuropneumoniae-specific polyclonal antibody and by fluorescent in situ hybridization. Viable bacteria from the farm drinking water were detected using the Live/Dead BacLight stain. Additionally, viable A. pleuropneumoniae was selected and isolated using the cAMP test and the identity of the isolated bacteria were confirmed by Gram staining, a specific polyclonal antibody and an A. pleuropneumoniae-specific PCR. Furthermore, biofilms were observed by scanning electron microscopy in A. pleuropneumoniae-positive samples. In conclusion, our data suggest that viable A. pleuropneumoniae is present in the drinking water of swine farms and may use biofilm as a strategy to survive in the environment.