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Publications (59)
The two-component system GacS/A and the posttranscriptional control system Rsm constitute a genetic regulation pathway in Gammaproteobacteria; in some species of Pseudomonas, this pathway is part of a multikinase network (MKN) that regulates the activity of the Rsm system. In this network, the activity of GacS is controlled by other kinases. One of...
The Pseudomonas aeruginosa genome can change to adapt to different ecological niches. We compared four genomes from a Mexican hospital and 59 genomes from GenBank from different niches, such as urine, sputum, and environmental. The ST analysis showed that high-risk STs (ST235, ST773, and ST27) were present in the genomes of the three niches from Ge...
blaIMP and blaVIM are the most detected plasmid-encoded carbapenemase genes in Pseudomonas aeruginosa. Previous studies have reported plasmid sequences carrying blaIMP variants, except blaIMP-56. In this study, we aimed to characterize a plasmid carrying blaIMP-56 in a P. aeruginosa strain isolated from a Mexican hospital. The whole genome of P. ae...
[This corrects the article DOI: 10.3389/fmicb.2022.845473.].
Las bacterias son quizá los microorganismos más ubicuos en el planeta, los podemos encontrar prácticamente en todos lados, adaptándose exitosamente a ambientes tan distintos como el estómago del humano y el grifo del agua. Para poder adaptarse y sobrevivir requieren percibirlas condiciones ambientales y responder a estas. A diferencia de los animal...
Aunque por muchos años se pensó que era poco probable que las bacterias se comunicaran entre sí estableciendo un comportamiento “social”, numerosos estudios realizados en las tres últimas décadas revelaron que las bacterias si se comunican entre sí, y no solo eso, se pueden censar o contar. Los sistemas de comunicación que usan las bacterias para t...
Azotobacter vinelandii is a soil bacterium that produces alginates, a family of polymers of biotechnological interest. In A. vinelandii, alginate production is controlled by the two-component system GacS/GacA. GacS/GacA, in turn, regulates the Rsm post-transcriptional regulatory system establishing a cascade that regulates alginate biosynthesis by...
Alginates are a family of polymers composed of guluronate and mannuronate monomers joined by β (1–4) links. The different types of alginates have variations in their monomer content and molecular weight, which determine the rheological properties and their applications. In industry, alginates are commonly used as additives capable of viscosifying,...
Azotobacter vinelandii is a motile bacterium that possesses an unusual pattern of peritrichous flagellation for members of the Pseudomonadaceae family. Unlike what has been reported for Pseudomonas spp. FleQ is not the master regulator of motility in A. vinelandii, this role is performed by FlhDC. Other factors involved in the regulation of motilit...
Azotobacter vineladii is a Gram-negative bacterium that produces alginate and poly-hydroxybutyrate (PHB), two polymers of biotechnological interest. This bacterium has the ability to form desiccation-resistant cysts. In the cyst the membrane phospholipids are replaced with a family of phenolic lipids called alkylresorcinols (ARs). The alginate, PHB...
Aim:
The present investigation was aimed at isolating and identifying bacterial strains from cured vanilla beans. Additionally, the study focused on evaluating bacterial processes pertaining to the aromatic compounds production (ACP).
Methods and results:
Three bacteria were isolated from Vanilla planifolia beans, previously subjected to the cur...
Acinetobacter calcoaceticus-baumannii complex isolates have been frequently associated with hospital and community infections, with A. baumannii being the most common. Other Acinetobacter spp. not belonging to this complex also cause infections in hospital settings, and the incidence has increased over the past few years. Some species of the Acinet...
A random transposition mutant library of B. gladioli UAPS07070 was analyzed for searching mutants with impaired microbial antagonism. Three derivates showed diminished antimicrobial activity against a sensitive strain. The mutated loci showed high similarity to the quorum sensing genes of the AHL-synthase and its regulator. Another mutant was affec...
A random transposition mutant library of B. gladioli UAPS07070 was analyzed for searching mutants with impaired microbial antagonism. Three derivates showed diminished antimicrobial activity against a sensitive strain. The mutated loci showed high similarity to the quorum sensing genes of the AHL-synthase and its regulator. Another mutant was affec...
Dendrogram of 41 multidrug-resistant P. aeruginosa clinical isolates obtained in ISSSTE Regional Hospital of Puebla, Mexico.
Notes: The isolates showing a Dice coefficient ≥80% were considered as genetically related for this study. PFGE type (PT), PFGE clusters (A, B and C).
Abbreviation: PFGE, pulsed-field gel electrophoresis.
Plasmid extraction by the Quick Prep method of 17 clinical blaIMP-carrying P. aeruginosa isolates.
Notes: The position of chromosomal DNA is indicated by an arrow at the right. Line 1: Size marker; Line 2: PE06; Line 3: PE09; Line 4: PE15; Line 5: PE16; Line 6: PE20; Line 7: PE21; Line 8: PE22; Line 9: PE23; Line 10: PE27; Line 11: PE46; Line 12: P...
Purpose
Pseudomonas aeruginosa infections in hospitals constitute an important problem due to the increasing multidrug resistance (MDR) and carbapenems resistance. The knowledge of resistance mechanisms in Pseudomonas strains is an important issue for an adequate antimicrobial treatment. Therefore, the objective was to investigate other antimicrobi...
The GacS/A system in Azotobacter vinelandii regulates alginate and alkylresorcinols production through RsmZ1, a small regulatory RNA (sRNA) that releases the translational repression of the algD and arpR mRNAs caused by the RsmA protein. In the Pseudomonadaceae family, the Rsm-sRNAs are grouped into three families: RsmX, RmsY and RsmZ. Besides RsmZ...
Plant growth-promoting rhizobacteria (PGPR) increase plant growth and crop productivity. The inoculation of plants with a bacterial mixture (consortium) apparently provides greater benefits to plant growth than inoculation with a single bacterial strain. In the present work, a bacterial consortium was formulated containing four compatible and desic...
Bacterial growth in SYP or PY-Ca liquid media for bacteria grown individually or all together.
(PDF)
Physicochemical characteristics of the soils used for support in the desiccation experiments.
(PDF)
Siderophore production of the four strains chosen for the bacterial consortium.
(PDF)
Sequence identity of 16S rRNA from Acinetobacter sp. strain EMM02.
(DOCX)
Number of bacteria present in suspensions used for the inoculation of maize.
(DOCX)
Colonization of the rhizosphere of maize plants by the bacterial strains.
(DOCX)
Flow chart illustrating the identification of Acinetobacter sp. EMM02 by the amplification and sequencing of the gene encoding 16S rRNA.
(PDF)
Restriction patterns of the amplified gene encoding the 16S rRNA of the bacterial strains isolated from plants.
(PDF)
Adhesion of strains to maize seeds sown in vermiculite.
(DOCX)
Strains used in this study.
(DOCX)
Methanol-consuming culturable bacteria were isolated from the plant surface, rhizosphere, and inside the stem of Neobuxbaumia macrocephala. All 38 isolates were facultative methylotrophic microorganisms. Their classification included the Classes Actinobacteria, Sphingobacteriia, Alpha-, Beta-, and Gammaproteobacteria. The deduced amino acid sequenc...
Azotobacter vinelandii, belonging to the Pseudomonadaceae family, is a free-living bacterium that has been considered to be a good source for the production of bacterial polymers such as alginate. In A. vinelandii the synthesis of this polymer is regulated by the Gac/Rsm post-transcriptional regulatory system, in which the RsmA protein binds to the...
Purpose:
Haemophilus influenzae is a commensal organism found in the upper respiratory tract of humans. When H. influenzae becomes a pathogen, these bacteria can move out of their commensal niche and cause multiple respiratory tract diseases such as otitis media, sinusitis, conjunctivitis and bronchitis in children, and chronic obstructive pulmona...
Objectives:
The resistance mechanisms, molecular type and plasmid content of cefotaxime-resistant Escherichia coli isolated from faecal samples of healthy volunteers in Puebla, Mexico, were characterised.
Methods and results:
Cefotaxime-resistant E. coli were recovered from 11 (18%) of 60 healthy volunteers. The isolates (one per sample) were ch...
Pseudomonas putida KT2440 is a bacterium able to colonize plant roots and degrade toxic compounds from environment. The aim of present work was to evaluate the ability of this bacterium to promote the growth of autochthonous blue maize under two conditions of temperature: 30 and 40 oC. In this work we observed that the evaluated bacterium promoted...
Multidrug-resistant bacteria are a growing problem in different environments and hosts, but scarce information exists about their prevalence in reptiles. The aim of this study was to analyze the resistance mechanisms, molecular typing, and plasmid content of cefotaxime-resistant (CTX(R)) Escherichia coli isolates recovered from cloacal samples of 7...
Azotobacter vinelandii is a soil bacterium
that undergoes differentiation
to form cysts resistant
to desiccation. Alginate, polyhydroxybutyrate
(PHB) and alkylresorcinols (AR) are structural components
of the cysts. The synthesis of these compounds has been shown to be under control of the Gac/Rsm signal transduction pathway. This pathway includes...
The genus Klebsiella belongs to Enterobacteriaceae family, and currently is considered to be non-motile and non-flagellated. In the present work, 25 Klebsiella strains isolated from nosocomial infections were assessed for motility under different growth conditions. One Klebsiella isolate, KpBuap021 demonstrated a swim-like motility phenotype. The K...
Azotobacter vinelandii is a soil bacterium that forms desiccation-resistant cysts, and the exopolysaccharide alginate is essential for this process. A. vinelandii also produces alginate under vegetative growth conditions, and this production has biotechnological significance. Poly-β-hydroxybutyrate (PHB) is another polymer synthetized by A. vinelan...
Azotobacter vinelandii is a soil bacterium that undergoes a differentiation process that forms cysts resistant to desiccation. During encystment, a family of alkylresorcinols lipids (ARs) are synthesized and become part of the membrane and are also components of the outer layer covering the cyst, where they play a structural role. The synthesis of...
Effect of inactivation of gacA on the expression of rsmZ1 under vegetative growth (A), and under encystment conditions (B).
The expression levels of rsmZ1 at different times were quantified as ß-glucuronidase activity of strains containing an rsmZ1::gusA transcriptional fusion. Black bars represent the expression levels of a SW136 wild type derivat...
Plasmids and strains used in this study.
(DOCX)
Several rhizospheric bacteria with potential to stimulate the plant
growth have been isolated from different places and regions of the
world. The mechanisms by which rhizospheric bacteria have the
ability to stimulate plant growth include phytohormone production,
volatiles compounds, antimicrobial compounds (lytic enzymes
production, siderophores),...
Upon encystment induction, Azotobacter vinelandii produces the phenolic lipids alkylresorcinols (ARs) that are structural components of the cysts. The enzymes responsible for the ARs synthesis are encoded in the arsABCD operon, whose expression is activated by ArpR. The transcription of arpR is initiated from an RpoS dependent promoter. The nitroge...
In Azotobacter vinelandii, a cyst forming bacterium, the alternative sigma factor RpoS is essential to form cysts resistant to desiccation and to synthesize the cyst specific lipids alkylresorcinols. In this study, we carried out a proteome analysis of vegetative cells and cysts of A. vinelandii strain AEIV and its rpoS mutant derivative AErpoS. Th...
Pineapple is the second most important tropical fruit in international trade and Mexico ranks ninth in world production. Pink disease is asymptomatic in the field and is characterized by the production of dark discoloration (amber-reddish brown) and its initial effects are not recognized until the fruits are cored and canned. Hence pink disease is...
In Azotobacter vinelandii the two-component GacS/GacA system is required for synthesis of polyhydroxybutyrate (PHB) and of the exopolysaccharide alginate. The RsmA protein was shown to interact with the alginate biosynthetic algD mRNA, acting as a translational repressor, and GacA was found to activate transcription of the rsmZ1 and rsmZ2 genes tha...
Azotobacter vinelandii is a soil bacterium that undergoes differentiation to form cysts that are resistant to desiccation. Upon induction of cyst formation, the bacterium synthesizes alkylresorcinols that are present in cysts but not in vegetative cells. Alternative sigma factors play important roles in differentiation. In A. vinelandii, AlgU (sigm...
Azotobacter vinelandii is a soil bacterium that produces the polysaccharide alginate. The two-component system GacS/GacA is required for alginate synthesis since a mutation in gacS or gacA significantly reduced the level of transcripts of algD, the gene encoding GDP-mannose dehydrogenase, a key enzyme of the alginate biosynthetic pathway. In many γ...
Pink disease is a major problem in the pineapple canning industry. Affected fruit acquire a brownish pigment after pasteurization and can contaminate non-affected fruit before they are released to the consumer. In the last few years, Pantoea citrea has been described as the causative agent of pink disease. In this study, over 300 bacterial isolates...
Bacterial isolates from maize plants showing a leaf spot disease were identified through molecular and phenotypic traits,
showing that the isolates belong to Pantoea ananatis. Maize plants inoculated with those isolates showed a pathogenic reaction. This is the first report of a disease of Mexican
maize caused by P. ananatis.
Additional keywordsEn...
During encystment of Azotobacter vinelandii, a family of alkylresorcinols (ARs) and alkylpyrones (APs) are synthesized. In the mature cyst, these lipids replace the
membrane phospholipids and are also components of the layers covering the cyst. In this study, A. vinelandii strains unable to synthesize ARs were isolated after mini-Tn5 mutagenesis. C...
O-Acetylserine (thiol)-lyase (cysteine synthase) was purified from Azospirillum brasilense Sp7. After hydrolysis of the purified protein, amino acid sequences of five peptides were obtained, which permitted the cloning and sequencing of the cysK gene. The deduced amino acid sequence of cysteine synthase exhibited homology with several putative prot...
Azotobacter vinelandii is a soil -proteobacteria that fixes nitrogen and forms desiccation-resistant cysts. The exopolysaccharide alginate is an integral part of the layers surrounding the cysts. Here, we reported the cloning of A. vinelandii algC, encoding the enzyme catalyzing the second step of alginate pathway. We showed that AlgC is involved n...
Azotobacter vinelandii is a soil gamma-proteobacteria that fixes nitrogen and forms desiccation-resistant cysts. The exopolysaccharide alginate is an integral part of the layers surrounding the cysts. Here, we reported the cloning of A. vinelandii algC, encoding the enzyme catalyzing the second step of alginate pathway. We showed that AlgC is invol...
Transcription of the Azotobacter vinelandii algDgene, which encodes GDP-mannose dehydrogenase (the rate-limiting enzyme of alginate synthesis), starts from three sites: p1,
p2, and p3. The sensor kinase GacS, a member of the two-component regulatory system, is required for transcription of algD from its three sites during the stationary phase. Here...
Azotobacter vinelandii produces two polymers: the extracellular polysaccharide alginate and the intracellular polyester poly-β-hydroxybutyrate (PHB).
A cosmid clone (pSMU588) from anA. vinelandii gene library diminished alginate production by A. vinelandii mucoid strain ATCC 9046. The nucleotide sequence and predicted amino acid sequence of the loc...
