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Gestational diabetes (GD), pre-gestational diabetes (PD), and pre-eclampsia (PE) are morbidities affecting gestational health which have been associated with dysbiosis of the mother’s gut microbiota. This study aimed to assess the extent of change in the gut microbiota diversity, short-chain fatty acids (SCFA) production, and fecal metabolites profile in a sample of Mexican women affected by these disorders. Fecal samples were collected from women with GD, PD, or PE in the third trimester of pregnancy, along with clinical and biochemical data. Gut microbiota was characterized by high-throughput DNA sequencing of V3-16S rRNA gene libraries; SCFA and metabolites were measured by High-Pressure Liquid Chromatography (HPLC) and (Fourier Transform Ion Cyclotron Mass Spectrometry (FT-ICR MS), respectively, in extracts prepared from feces. Although the results for fecal microbiota did not show statistically significant differences in alfa diversity for GD, PD, and PE concerning controls, there was a difference in beta diversity for GD versus CO, and a high abundance of Proteobacteria, followed by Firmicutes and Bacteroidota among gestational health conditions. DESeq2 analysis revealed bacterial genera associated with each health condition; the Spearman’s correlation analyses showed selected anthropometric, biochemical, dietary, and SCFA metadata associated with specific bacterial abundances, and although the HPLC did not show relevant differences in SCFA content among the studied groups, FT-ICR MS disclosed the presence of interesting metabolites of complex phenolic, valeric, arachidic, and caprylic acid nature. The major conclusion of our work is that GD, PD, and PE are associated with fecal bacterial microbiota profiles, with distinct predictive metagenomes.

Background Human milk is the best food for infants; however, when breastfeeding is not possible, pasteurized milk from human milk banks is the best alternative. Little has been reported about variations in the bacterial microbiota composition of human milk after pasteurization. Research aim To characterize and compare the bacterial microbiota composition and diversity within human milk among Mexican mothers before and after the Holder pasteurization process. Methods A cross-sectional, observational, and comparative design was used. The effect of the pasteurization process on the bacterial composition and diversity of human milk samples of donors ( N = 42) from a public milk bank was assessed before and after pasteurization by high throughput deoxyribonucleic acid sequencing of V3-16S rRNA gene libraries. Sequencing data were examined using the Quantitative Insights into Microbial Ecology software and Phyloseq in R environment. Results A varied community of bacteria was found in both raw and pasteurized human milk. The bacterial diversity of the milk samples was increased by the pasteurization, where some thermoduric bacteria of the phyla Proteobacteria, Firmicutes, and Actinobacteria were more abundant. The source tracker analysis indicated that at most 1.0% of bacteria may have come from another source, showing the safety of the process used to treat milk samples. Conclusion The pasteurization process increased the bacterial diversity. We selected taxa capable of surviving the process, which could proliferate after the treatment without being a risk for infants.

Horses are non-ruminant, herbivorous mammals, been used through history for various purposes, with a gut microbiota from cecum to the colon, possessing remarkable fermentative capacity. We studied the fecal microbiota of Azteca, Criollo, Frisian, Iberian, Pinto, Quarter and Spanish horse breeds living in Mexico by next-generation DNA sequencing of 16S rRNA gene libraries. Dominant phyla Firmicutes, Bacteroidetes, Proteobacteria, Spirochaetes, Fibrobacteres, Actinobacteria and Verrucomicrobia have different relative abundances among breeds, with contrasted alpha and beta diversities as well. Heatmap analysis revealed that Ruminococcaceae, Lachnospiraceae, Mogibacteriaceae families, and order Clostridiales are more abundant in Spanish, Azteca, Quarter and Criollo breeds. The LEfSe analysis displayed higher abundance of order Bacteroidales, family BS11, and genera Faecalibacterium, Comamonas, Collinsella, Acetobacter, and Treponema in Criollo, Azteca, Iberian, Spanish, Frisian, Pinto, and Quarter horse breeds. The conclusion is that dominant bacterial taxa, found in fecal samples of horse breeds living in Mexico, have different relative abundances.

Microbiota acquired during labor and through the first days of life contributes to the newborn’s immune maturation and development. Mother provides probiotics and prebiotics factors through colostrum and maternal milk to shape the first neonatal microbiota. Previous works have reported that immunoglobulin A (IgA) secreted in colostrum is coating a fraction of maternal microbiota. Thus, to better characterize this IgA-microbiota association, we used flow cytometry coupled with 16S rRNA gene sequencing (IgA-Seq) in human colostrum and neonatal feces. We identified IgA bound bacteria (IgA+) and characterized their diversity and composition shared in colostrum fractions and neonatal fecal bacteria. We found that IgA2 is mainly associated withBifidobacterium,Pseudomonas, Lactobacillus, andParacoccus, among other genera shared in colostrum and neonatal fecal samples. We found that metabolic pathways related to epithelial adhesion and carbohydrate consumption are enriched within the IgA2+ fecal microbiota. The association of IgA2 with specific bacteria could be explained because these antibodies recognize common antigens expressed on the surface of these bacterial genera. Our data suggest a preferential targeting of commensal bacteria by IgA2, revealing a possible function of maternal IgA2 in the shaping of the fecal microbial composition in the neonate during the first days of life.

COVID-19 is a severe respiratory disease threatening pregnant women, which increases the possibility of adverse pregnancy outcomes. Several recent studies have demonstrated the ability of SARS-CoV-2 to infect the mother enterocytes, disturbing the gut microbiota diversity. The aim of this study was to characterize the entero-mammary microbiota of women in the presence of the virus during delivery. Fifty mother–neonate pairs were included in a transversal descriptive work. The presence of SARS-CoV-2 RNA was detected in nasopharyngeal, mother rectal swabs (MRS) and neonate rectal swabs (NRS) collected from the pairs, and human colostrum (HC) samples collected from mothers. The microbiota diversity was characterized by high-throughput DNA sequencing of V3-16S rRNA gene libraries prepared from HC, MRS, and NRS. Data were analyzed with QIIME2 and R. Our results indicate that several bacterial taxa are highly abundant in MRS positive for SARS-CoV-2 RNA. These bacteria mostly belong to the Firmicutes phylum; for instance, the families Bifidobacteriaceae, Oscillospiraceae, and Microbacteriaceae have been previously associated with anti-inflammatory effects, which could explain the capability of women to overcome the infection. All samples, both positive and negative for SARS-CoV-2, featured a high abundance of the Firmicutes phylum. Further data analysis showed that nearly 20% of the bacterial diversity found in HC was also identified in MRS. Spearman correlation analysis highlighted that some genera of the Proteobacteria and Actinobacteria phyla were negatively correlated with MRS and NRS (p < 0.005). This study provides new insights into the gut microbiota of pregnant women and their potential association with a better outcome during SARS-CoV-2 infection.

Bouvardia ternifolia is a medicinal plant considered a source of therapeutic compounds, like the antitumoral cyclohexapeptide bouvardin. It is known that large number of secondary metabolites produced by plants results from the interaction of the host and adjacent or embedded microorganisms. Using high-throughput DNA sequencing of V3-16S and V5-18S ribosomal gene libraries, we characterized the endophytic, endophytic + epiphyte bacterial, and fungal communities associated to flowers, leaves, stems, and roots, as well as the rhizosphere. The Proteobacteria (average 80.7%) and Actinobacteria (average 14.7%) were the most abundant bacterial phyla, while Leotiomycetes (average 54.8%) and Dothideomycetes (average 27.4%) were the most abundant fungal classes. Differential abundance for the bacterial endophyte group showed a predominance of Erwinia, Propionibacterium, and Microbacterium genera, while Sclerotinia, Coccomyces, and Calycina genera predominated for fungi. The predictive metagenome analysis for bacteria showed significative abundance of pathways for secondary metabolite production, while a FUNguild analysis revealed the presence of pathotroph, symbiotroph, and saprotrophs in the fungal community. Intra and inter copresence and mutual exclusion interactions were identified for bacterial and fungal kingdoms in the endophyte communities. This work provides a description of the diversity and composition of bacterial and fungal microorganisms living in flowers, leaves, stems, roots, and the rhizosphere of this medicinal plant; thus, it paves the way towards an integral understanding in the production of therapeutic metabolites.

Background: Microbiota colonization during labor and through the first meals contributes to immune maturation and development of the newborn. Mother provides probiotics and prebiotics factors through colostrum and maternal milk to shape the first neonatal microbiota. Previous works have reported that immunoglobulin A (IgA) secreted in colostrum is coating a fraction of maternal microbiota. Methods: Thus, to better characterize the IgA-associated microbiota, we used flow cytometry coupled with 16S rDNA gene sequencing (IgA-Seq) in human colostrum and neonatal feces. We identified IgA-bound bacteria (IgA+) and characterized its diversity to elucidate possible role of IgA subclasses during neonatal bacterial colonization of the colon.Results: We found that IgA2 in the colostrum has an active role during microbiota colonization. Colostrum IgA2 is mainly associated with Bifidobacterium, Lactobacillus, and Bacteroidetes genera. This association seems to give these bacteria an advantage during their establishment since metabolic pathways related to epithelial adhesion and carbohydrate consumption are enriched within fecal IgA2+ microbiota. Association with specific bacteria could be explained since IgA2 recognizes common antigens expressed on surfaces among bacteria genera.Conclusions: Our data suggest a specific targeting of commensal bacteria by IgA2 revealing a specialized function of IgA microbiota association during neonatal intestinal colonization during the first days of life.

Introduction. Anaerobic digestion (AD) is considered one of the most beneficial technologies for the treatment of organic wastes, from which energy in form of biogas and digestate as a soil amendment can be obtained. However, AD often suffers from process instability due to high levels of inorganic toxic substances such as ammonium, phosphates, sulfates or metal ions, variations in operating parameters such as temperature and pH, as well as a lack of proper balance between microbial groups. One of the alternatives to combat these imbalances is bioaugmentation, which is defined as the addition of specific microorganisms (either pure cultures or microbial consortia) into the system to accomplish a certain function. In this work, hydrogenotrophic methanogens were used to improve the methane yield of a thermophilic AD process of the organic fraction of municipal solid wastes (OFMSW) in Mexico City. Methods. The OFMSW (substrate) and leachate (inoculum) were collected from a composting plant in Mexico City. The consortium containing the hydrogenotrophic methanogens was isolated from the leachate. A biochemical methane potential (BMP) test was performed to know if the consortium influenced the methane yield. A 1:1 volatile solids (VS) ratio substrate/inoculum was operated in 125 mL serum bottles with a working volume of 60 ml. The consortium was added to different volume ratios. The process lasted 32 days at 55° C and 60 rpm. The identification of the microbial communities of all treatment groups and consortium were done by high throughput DNA sequencing of bacterial and archaeal 16S rDNA libraries. Results. The highest yield >600 ml CH4/g VSadded was achieved when 25% of the consortium was added followed by 50%; however, between these two treatments, there was not a statistically significant difference. The rest of the treatments were under 600 ml CH4/g VSadded. Nevertheless, it should be noted that the treatment at 25% reached its methane peak after 10 days, meanwhile, the treatment at 50% reached it on approximately 8 days, suggesting in this last treatment, the generation of methane was more accelerated. The methane yield increased by approximately 7% and 5% compared to the control (0%), while using 25% and 50% of the consortium, respectively. Regarding the bacterial communities, it was found that the consortium was mainly composed of members of the phylum Synergistetes. Members of this phylum are known for their acetate oxidizing properties. In all the treatments the phyla Firmicutes, Thermotogae, and Synergistetes were dominant and as the concentration of the consortium in the treatments increased, the presence of the family Thermotogaceae also increased. Conclusions. In this research, we detected that the bioaugmentation using hydrogenotrophic methanogens improved the methane yield of the AD process by more than 5%. The bacterial communities present in the consortium have capacities to degrade cellulolytic compounds and act as acetate oxidants, which play a role in syntrophy with hydrogenotrophic methanogens, however, it is still necessary to know the dynamics of the methanogens. Acknowledgments. The project was supported by CIIEMAD IPN SIP 20172277, 20180942, 20195607, and CONACyT-163235 INFR-2011-01. AKGB was granted a CONACyT-700337 doctorate scholarship.

Introduction. Bouvardia ternifolia is a Mexican endemic plant used in the past as a general curative source and contemporaneously as a remedy for dysentery, poison therapy, pain relief, and other afflictions. The hydroalcoholic extract shows acetylcholinesterase inhibition activity, as well as anti-inflammatory and antioxidant effects. “Bouvardin” is a cyclic hexapeptide found in B. ternifolia with in vitro cytotoxicity against B16 melanoma melanotic and P388 lymphocytic leukemia cell lines. These findings support the idea that this plant has potential as a source of therapeutic bioactive compounds. It is well known that many therapeutic secondary metabolites can be produced by plant-associated microorganisms and in the search of these, the characterization of species that live in conjunction with the plant becomes an important research activity. In this study, we report the characterization of the bacterial community associated with the Mexican medicinal plant B. ternifolia. Material and methods. Five specimens and plant-soil samples were collected from different regions from the central part of Mexico and fractioned in flower, stem, leaf, and root. To establish the total and endophytic bacterial communities, each plant fraction was divided into two subfractions; the first one was processed directly and the second one was carefully tissue-surface sterilized before processing with chemical agents. Bacteria present in subfractions were collected by crushing down the plant tissue in a mortar followed by centrifugation steps. FavorPrep stool DNA isolation kit # FASTI001-1 and QIAGEN Dneasy PowerSoil kit were used to purify bacterial DNA which was employed to sequence a DNA library prepared from the V3 region of the 16S ribosomal gene by Ion Torrent PGM NGS system technology. Results. We find ~1,000 OTUs shared among total plant, endophytic, and soil samples, ~2,000 OTUs exclusively for soil bacteria, ~1,500 OTU’s for total plant bacteria, and ~250 OTUs for endophytic bacteria. Proteobacteria (46-79%) was the most representative phylum followed by Actinobacteria and Acidobacteria. The phylum Cyanobacteria (8.5%) was more representative in endophytes samples than in total plant samples (1%). Bacterial richness and diversity by plant fractions and soil, from highest to lowest was observed in the following order: Soil > Root > Leaf > Stem > Flower. Linear discriminant effect size analysis showed the order Streptophyta, the families Oxalobacteraceae, Ruminococcaceae, Lachnospiraceae, and the genera Propionilbacterium, Paracoccus, Lactobacillus as the most representative taxa in endophyte bacterial samples. Conclusions. This study provides evidence for the composition and diversity of the bacterial communities present in soil and tissues of the Mexican medicinal plant B. ternifolia which can be considered for subsequent analysis to profiling therapeutic and bioactive compounds that give this species its medicinal properties. Acknowledgments. This work was financed by Cinvestav, FONCICYT 2 267416, CONACYT-BMBF-267416, and CONACyT-163235 INFR-2011-01.

Introduction. Alzheimer´s disease (AD) is the most common dementia in aged population and is characterized by cognitive impairment and dysbiosis, not to mention amyloid plaques, neurofibrillary tangles and reactive gliosis as the main hallmarks in the brain. Currently, there is not an effective treatment against this condition. Recent reports have suggested an elevated abundance of pro-inflammatory bacteria in the gut microbiota (GM) of transgenic (Tg) AD models compared to wild type (WT) animals. Moreover, the short chain fatty acids (SCFAs) propionate and butyrate, produced by GM, have been reported as pro- and anti-inflammatory species respectively. Methods. In order to determine changes in GM diversity and SCFAs concentration related with cognitive impairment in AD pathology, we used 6 months-old WT and AD Tg male mice to evaluate working and spatial memory status utilizing T- and water-maze paradigms respectively, SCFAs (acetate, propionate and butyrate) concentration in feces using high performance liquid chromatography (HPLC), and GM diversity, enrichment and functional predictive metabolism by DNA sequencing. Results. We observed increases in the proportion of lactic acid bacterial taxa, and also in the concentration, proportion and predictive metabolism of propionate for Tg compared to WT mice. Acetate and butyrate fecal amounts, in addition to working and spatial memory scores, were decreased in Tg animals. Conclusions. Our data suggests lactic acid bacterial increases, acetate and butyrate reductions, and an enhanced propionate metabolism and production could be related with AD pathology. Further studies are need in order to attribute cognitive dysfunctions to these changes.

Introduction. In previous studies, it has been observed that the concentration of some components of breast milk such as proteins, carbohydrates, lipids among others vary throughout the day. In the same way, it has been observed that bacteria diversity undergoes changes at the same time interval. In human milk there are also beneficial bacteria from the mother that are transferred to the newborn by breastfeeding, being the main source of colonizing bacteria of the newborn's gastrointestinal tract. Many of these bacterial communities display oscillations throughout the day, contributing to homeostasis and play an important role in various physiological processes. It is reported that the healthy human microbiome is regulated by the circadian cycle, where fluctuations in abundance of the bacterial community occur, in addition to a relationship in feeding times and sleep cycles of the mother. The aim of this work was to identify possible fluctuations and variations in bacterial diversity and composition on human milk throughout the day. Methods Human milk samples were collected during 5 consecutive days from Monday to Friday at three different times, approximately every 8 hours: Morning (7:00 am), Afternoon (3:00 pm), and night (10:00 pm). Samples were manually collected in aseptic conditions and immediately freeze at -20° C. Bacterial DNA was extracted using the Favorgen stool kit. The diversity was characterized by high-throughput DNA sequencing of V3-16S rDNA libraries. The sequencing data were analyzed using the QIIME pipeline and taxonomy was assigned by comparison of the sequences against the Greengenes reference database. Alpha diversity was determined using Phyloseq and ggplot2 packages in the R environment (v3.4.4). For beta diversity, the dissimilarity was estimated using unweighted Bray Curtis analysis. The linear discriminant analysis effect size program (LEfSe v1.0) was used to detect significant differences in the relative abundances of bacterial taxa. Results. The human milk microbiota shows changes in the bacterial composition between morning and night; also, we observed significant changes in the Shannon diversity index between both groups. On the other hand, no differences were observed in the bacterial composition or alfa diversity in the afternoon samples compared with the morning and night samples. For beta diversity analysis, no clustering was observed among all the samples. As previously has been reported, Lactobacillus was found more enriched in the night milk of samples with statistical significance; same was observed for environmental proteobacteria and actinobacteria. The family Micrococcaceae was detected as more abundant in samples collected in the morning. Conclusions. As for other human milk components, the human milk microbiota seems to be affected by the daytime changes. The results presented in this work suggest that the milk microbiota exhibits diurnal fluctuation resulting in a time-of-day specific taxonomic arrangement. Acknowledgments. Work supported by Cinvestav and CONACyT 163235 INFR-2011-01 grant; and CONACYT doctorate scholarship 777953 (KCC), 291236 (FHQ), and master’s degree scholarship 997494 (NGZT).

Introduction. Cervical cancer is an important health issue worldwide. Many factors are related to this condition as persistent human papillomavirus infection, the use of hormonal contraceptives, pH changes, and bacterial vaginosis. The association between the microbiota and cervical cancer is an interesting issue; given that environmental and hormonal factors changing the vaginal microbiota may contribute to cancer. Methods Using High-throughput DNA sequencing of V3-16S rDNA libraries, we determined the bacterial diversity in cervicovaginal lavages and fecal samples at different stages of cervical cancer development in the K14HPV16E7 mice model under +/- 17β-estradiol (E2) stimulus and compared it with an isogenic control (FVB). Results. We found that continuous E2 administration during 6 months in the model with type 16 E7 expression causing the development of cancer, is associated with significant changes in the microbiota diversity in the cervicovaginal lavages. Similar results were not observed in the model when no E2 was administered neither in the FVB mice. Comparable changes in the microbiota diversity of fecal samples were not observed. Conclusions. The persistent expression of E7 oncogene or the 17β-estradiol for longer periods of time, cause changes in the vaginal microbiota diversity and the cervical epithelium not necessarily leading to cervical cancer; however, the combined action of both, causes cervical carcinoma and defined changes in the abundance of bacterial taxa in the cervicovaginal lavages, suggesting a specific organ effect of E7 expression associated to E2 on the vaginal microbiota. Acknowledgments. Work supported by Cinvestav and CONACyT 163235 INFR-2011-01, FONSEC SS/IMSS/ISSSTE-CONACYT-233361, and CONACyT 0201904 grants.

Background Human milk microbiota plays a role in the bacterial colonization of the neonatal gut, which has important consequences in the health and development of the newborn. However, there are few studies about the vertical transfer of bacteria from mother to infant in Latin American populations. Methods We performed a cross-sectional study characterizing the bacterial diversity of 67 human milk-neonatal stool pairs by high-throughput sequencing of V3-16S rDNA libraries, to assess the effect of the human milk microbiota on the bacterial composition of the neonate’s gut at early days. Results Human milk showed higher microbial diversity as compared to the neonatal stool. Members of the Staphylococcaceae and Sphingomonadaceae families were more prevalent in human milk, whereas the Pseudomonadaceae family, Clostridium and Bifidobacterium genera were in the neonatal stool. The delivery mode showed association with the neonatal gut microbiota diversity, but not with the human milk microbiota diversity; for instance, neonates born by C-section showed greater richness and diversity in stool microbiota than those born vaginally. We found 25 bacterial taxa shared by both ecosystems and 67.7% of bacteria found in neonate stool were predicted to originate from human milk. This study contributes to the knowledge of human milk and neonatal stool microbiota in healthy Mexican population and supports the idea of vertical mother-neonate transmission through exclusive breastfeeding.

Introduction: The impact of polluting substances, especially those of fossil fuels, on theenvironment is an important issue in the world. The ability of microorganisms to degradethese pollutants has been recently studied and characterized. Objective: To analyze the ability of groups of microorganisms, obtained from a cloudforest ecosystem in Mexico, to degrade aromatic compounds (benzene, toluene,ethylbenzene and anthracene). Materials and methods: Microbiome samples were collected in the Sierra Madre del Surin the state of Oaxaca. The microorganisms were isolated and identified by moleculartechniques. Subsequently, the ability of the microorganisms to degrade aromatichydrocarbons in a packed-bed bioreactor was quantitatively evaluated by HPLC-PDAchromatography. Results and discussion: Fifty groups of microorganisms were collected, cultured andgenetically characterized. In genetic diversity, Lactobacillus, Prevotella and genera of the2 family Acetobacteraceae predominated. In the hydrocarbon biodegradation process, thepollutant concentration decreased 97 % and 91 % mineralization was achieved in less than25 h. Conclusions: The microorganisms showed significant degrading activity of the aromaticcompounds. Biodiversity in the cloud forest in the Loxicha region is key to ensuringecosystem services, so it is important to undertake explorations to evaluate the use of thesebacterial microbiomes.

Introduction. The ready-to-eat food microbiota are the microorganisms present in the dishes that are currently consumed during the meals. These microorganisms include those that may have a health benefit, potentially pathogenic microorganisms, among others that have not yet been given a function. Foods that are suitable for human consumption are not free of microorganisms, however, within the food industry only yeasts have been given a beneficial function ready-to-eat food, while other microorganisms such as filamentous fungi and bacteria have been studied for their negative effect for food. Methods. Using High-throughput DNA sequencing of 16S rDNA libraries, we determined the bacterial diversity in different samples of high demanded freshly prepared unspoiled ready-to-eat Mexican dishes. Results. We found a great bacterial diversity. The most abundant bacterial phyla were Firmicutes, Proteobacteria, Bacteroidetes, Actinobacteria, TM7, Thermi, among others. The phyla included bacteria with remarkable abundance per type of dish. For instance, we found in the soups, the genera Microbacterium, and Anoxybacillus; in the main dishes the family Lachnospiraceae, the genus Dorea; in the dairy products, the genera Thermus, and Blautia; in the side plates, members of the family Aeromonadaceae, and the genus Kaistobacter; the beverages contained members of the family Enterobacteriaceae and the genus Lactobacillus, and finally the desserts, contained bacteria of the family Ruminococaceae, and the genus Victoria. We found a large abundance of chloroplast sequences, which were eliminated by filtering. The alfa diversity analyses showed that the main dishes had the largest diversity. The beta-diversity analyses clustered the bacterial communities of soups, side plates, desserts, and beverages, and some main dishes. Conclusions. Based on our results we conclude that unspoiled ready-to-eat Mexican dishes contain a rich diversity in the bacterial community, which may contribute to the organoleptic properties of the dishes without representing a sanitary risk for the consumers. Acknowledgments. The project was supported by Cinvestav and CONACyT 163235 INFR-2011-01.

Cervical cancer is an important health issue worldwide. Many factors are related to this condition as the persistence of human papillomavirus (HPV) infection (e.g. type 16 and 18), the use of hormonal contraceptives for long periods of time, pH changes and bacterial vaginosis. The association between the microbiota and cervical human cancer is an interesting issue to be explored; given that environmental and hormonal factors may change the vaginal microbiota contributing to this condition. Our hypothesis was that changes in the microbiota diversity is associated with the development of cervical cancer. We evaluated the microbiota diversity in vaginal lavages and fecal samples at different stages of cervical cancer development in a mice model (K14HPV16E7) with type 16 E7 oncogene expression (E7), under continuous or not continuous stimulus of 17β-estradiol (E2) and compared it with a non-transgenic isogenic control (FVB) under same conditions. Our results indicate that continuous E2 administration during 6 months in the model with type 16 E7 expression causing development of cancer, is associated with significant changes in the microbiota diversity of the cervicovaginal lavages. Similar results were not observed in the same model when no E2 was administered to the mice. The FVB mice with no E7 expression which do not develop cervical cancer, did not show comparable changes in the microbiota diversity when E2 was administered during the same period. Normal evolution of the cervical epithelium and microbiota diversity were observed for the FVB mice with no E2 administration. Large changes in the microbiota diversity in fecal samples were not observed suggesting a specific organ effect of E7 expression associated to E2 on the vaginal microbiota.

Cheese is a live food whose preparation involves procedures and microbial communities playing an important role for the final product. We characterized the bacterial and fungal diversity of seventeen different Mexican cheeses by high-throughput DNA sequencing of 16S/18S rDNA libraries. We propose the existence of bacterial and fungal core communities, where at genera level, bacteria include Streptococcus spp., Lactococcus spp., Lactobacillus spp., Aerococcus spp., and Weisella spp. while at species level, the fungal community includes Galactomyces reessii, Scheffersomyces stipitis, Saccharomyces cerevisiae (baker's yeast), and S. cerevisiae_rm11-1a. In addition to the bacterial and fungal core communities, we found members of the cheese microbiota that could be associated to other factors of the cheese manufacturing process. Co-occurrence analysis made in this work, indicates that bacterial and fungal communities maintain positive and negative interactions which are important to shape the resident microbial communities in cheeses. This work is a contribution to the description of the microbial diversity found in some Mexican cheeses.

A microbial community, able to use 2,4-D (2,4-dichlorophenoxyacetic acid) and dicamba (3,6-dichloro-2-methoxybenzoic acid) as carbon and energy sources, was selected in a continuously operated packed-bed column (PBC). Both active compounds are present in the Banvel herbicide. The predominant cultivable microorganisms isolated belong to the genera Burkholderia, Dyella, Mycobacterium, and Microbacterium. The presence of the catabolic genes tfdACD encoding enzymes involved in the 2,4-D metabolic pathway was evaluated for the bacterial isolates, with positive results for all of them. To evaluate the ability of the entire microbial community to degrade these herbicides in aerobic conditions a horizontal multistage-packed-bed reactor (HMPBR) was constructed. The reactor has four zones packed with fragments of volcanic rock, interspaced with four unpacked aerated zones. The continuous reactor, inoculated with the isolated microbial consortium, was run at increasing Banvel loading rates always operating in an aerobic environment and under steady-state conditions. In no case, 2,4-D or its main aromatic derivatives were detected in reactor's effluent, while dicamba was substantially degraded only at low loading rates. The highest degradation efficiencies of the herbicides were 100% for 2,4-D and 84% for dicamba. COD determinations showed that other components present in the commercial formulation of the herbicide were also removed. To evaluate changes in the diversity of the microbial consortium, massive semiconductor sequencing of 16S rDNA libraries was made. A remarkable variation in the bacterial diversity at phylum level, was observed in biofilm samples obtained from distinct packed bed zones of the reactor, and at different operating conditions.

In the present work we have used a double-hybrid assay in bacteria to identify a putative domain in E. coli PNPase required for in vivo interaction with RNase E. We used a 202 aa fragment of RNase E previously reported as the PNPase binding domain in this enzyme and a collection of 13 different fragments of 105 aa, spanning the entire sequence of 734 aa PNPase (GenBank Accession number NP_417633). Our results indicate that two clones of PNPase including residues 158–262 and residues 473–577 contain interaction sites for RNase E within a ββαββα domain configuration. Three-dimensional modeling of the E. coli PNPase based on the S. antibioticus protein structure indicates that the putative binding domain is located on the monomer surface, facing outward from the trimeric tertiary structure. Since a copy of the ββαββα domain is also found in RNase PH, we investigated and found an interaction with RNase E in a pull-down assay. We suggest this interaction takes place through the similar ββαββα domain present in the tertiary structure of this enzyme. Based on these results, we propose that RNase PH and RNase E could form functional assemblies in E. coli.

Obesity and overweight are health problems of multifactorial etiology, which may include changes in the microbiome. In Mexico, more than 30 % of the child population between 5 and 11 years of age suffer from being overweight or are obese, which makes it a public health issue in progress. The purpose of this work was to measure the short-chain fatty acid concentration by high-performance liquid chromatography (HPLC), and to characterize the bacterial diversity by ion torrent semiconductor sequencing, of 16S rDNA libraries prepared from stools collected from a sample of well-characterized Mexican children for normal weight, overweight, and obese conditions by anthropometric and biochemical criteria. We found that triglyceride levels are increased in overweight and obese children, who presented altered propionic and butyric acid concentrations in feces. In addition, although the colon microbiota did not show a clear bacterial dysbiosis among the three conditions, the abundance of some particular bacteria was changed with respect to normal controls. We conclude from our results that the imbalance in the abundance of at least nine different bacteria as well as altered short-chain fatty acid concentration in feces is associated to the overweight and obese conditions of Mexican children.

PNPase is a phosphate-dependent exonuclease of Escherichia coli required for growth in the cold. In this work we explored the effect of specific mutations in its two RNA binding domains KH and S1 on RNA binding, enzymatic activities, autoregulation and ability to grow at low temperature. We removed critical motifs that stabilize the hydrophobic core of each domain, as well as made a complete deletion of both (Delta KHS1) that severely impaired PNPase binding to RNA. Nevertheless, a residual RNA binding activity, possibly imputable to catalytic binding, could be observed even in the Delta KHS1 PNPase. These mutations also resulted in significant changes in the kinetic behavior of both phosphorolysis and polymerization activities of the enzyme, in particular for the double mutant Prip-Delta KHS1-H. Additionally, PNPases with mutations in these RNA binding domains did not autoregulate efficiently and were unable to complement the growth defect of a chromosomal Delta pnp mutation at 18 degrees C. Based on these results it appears that in E. coli the RNA binding domains of PNPase, in particular the KH domain, are vital at low temperature, when the stem-loop structures present in the target mRNAs are more stable and a machinery capable to degrade structured RNA may be essential. (c) 2007 Elsevier B.V. All rights reserved.

In the present work we have used a double-hybrid assay in bacteria to identify a putative domain in E. coli PNPase required for in vivo interaction with RNase E. We used a 202 aa fragment of RNase E previously reported as the PNPase binding domain in this enzyme and a collection of 13 different fragments of 105 aa, spanning the entire sequence of 734 aa PNPase (GenBank Accession number NP_417633). Our results indicate that two clones of PNPase including residues 158-262 and residues 473-577 contain interaction sites for RNase E within a betabetaalphabetabetaalpha domain configuration. Three-dimensional modeling of the E. coli PNPase based on the S. antibioticus protein structure indicates that the putative binding domain is located on the monomer surface, facing outward from the trimeric tertiary structure. Since a copy of the betabetaalphabetabetaalpha domain is also found in RNase PH, we investigated and found an interaction with RNase E in a pull-down assay. We suggest this interaction takes place through the similar betabetaalphabetabetaalpha domain present in the tertiary structure of this enzyme. Based on these results, we propose that RNase PH and RNase E could form functional assemblies in E. coli.