Levans production by Gluconacetobacter diazotrophicus

Background: Growth of Gluconacetobacter diazotrophicus with glucose as carbon an energy source has been extensively studied. However, there are no reports in the literature describing growth of G. diazotrophicus in cultures containing sucrose as carbon source. The first step in sucrose pathway and production of levans was investigated. Biomass, levans, gluconic acid and keto gluconic acids production and levansucrase activity were determined in cultures with different sucrose concentration and nitrogen sources. Results: The biomass production was maximal in cultures containing 100 g x L-1 sucrose and inorganic nitrogen. Gluconic acid production was observed under all conditions tested, at levels up to 9 g x L-1 in cultures with sucrose excess and biological N2-fixation (BNF). Keto gluconic acids were detectable only in cultures with sucrose excess and supplemented with organic nitrogen sources. Levans production, although observed in all cultures, was maximal in batch culture with 100 g x L-1 of sucrose and BNF, concomitant with a significant expression of extracellular levansucrase. Conclusions: Ours results not only describe some unknown aspects of G. diazotrophicus physiology, but open up the possibility of developing a technology of levans production by this organism using culture media with sucrose (or some cheaper substitute, like molasses) and without the addition of any N-source because of its ability of fixing atmospheric N2.

[Role of HLA-DR and HLA-DQ alleles in multibacillary leprosy and paucibacillary leprosy in the province of Chaco (Argentina)]. / Papel de las moléculas HLA-DR y HLA-DQ en la lepra multibacilar y paucibacilar en la provincia del Chaco; Argentina.

OBJECTIVES: Segregation analyses in several populations have suggested a relationship between specific human leukocyte antigen (HLA) class II alleles and the development of different types of leprosy. The aim of this study was to determine the frequency of HLA class II DR and DQ alleles among leprosy patients in Chaco province, northeast Argentina, in an effort to determine whether these alleles might be involved in the development of the multibacillary (MB) and paucibacillary (PB) forms of leprosy. PATIENTS AND METHODS: Samples from 89 leprosy patients (MB = 70, PB = 19) and 112 healthy control subjects were analyzed. The HLA-DRB1 and HLA-DQB1 alleles were determined by PCR amplification and reverse hybridization with sequence-specific oligonucleotide probes, and analyzed with the INNO-LiPA typing system and LiPA software. DQB1*0201/0202/0203 in patients with MB leprosy and DRB1*04 in patients with PB leprosy were detected at significantly lower frequencies as compared with the normal controls. RESULTS: These data indicate that DQB1* 0201/0202/0203 may be a protective factor in MB leprosy and DRB1*04 in PB leprosy. DISCUSSION: We attribute the differences between our findings and those of other authors to the fact that the Caucasian inhabitants of Chaco include a considerable mixture of South American natives (Guaraníes and Tobas).

Papel de las moléculas HLA-DR y HLA-DQ en la lepra multibacilar y paucibacilar en la provincia del Chaco; Argentina / Role of HLA-DR and HLA-DQ alleles in multibacillary leprosy and paucibacillary leprosy in the province of Chaco (Argentina)

Objetivo. En la lepra, el análisis de segregación en varias poblaciones humanas sugiere una relación de alelos particulares de los antígenos leucocitarios humanos (HLA) clase II con el desarrollo de las diferentes formas de la enfermedad. Con el objetivo de determinar si algún alelo de las moléculas de HLA clase II en la población de la provincia del Chaco, Argentina, podrían estar comprometidos en el desarrollo de algunas de las formas de lepra multibacilar (MB) y/o paucibacilar (PB), se determinó la frecuencia de los alelos de los loci DR y DQ en pacientes con lepra. Pacientes y métodos. Se analizaron 89 muestras de pacientes con lepra (MB 5 70; PB 5 19) y 112 controles sanos. Se determinaron los alelos del locus DR y DQ, utilizando amplificación genérica por reacción en cadena de la polimerasa (PCR) e hibridación reversa con oligonucleótidos específicos (LIPA KEY-INNOGENETICS). Se encontró una disminución en la frecuencia del alelo DQB1*0201/0202/0203 en pacientes con lepra multibacilar y disminución del alelo DRB1*04 en pacientes con lepra paucibacilar respecto a controles, ambos con significación estadística. Resultados. Según los resultados observados, DQB1*0201/0202/0203 podría ser un alelo de protección en la forma multibacilar de la lepra y el alelo DRB1*04 estaría relacionado con protección en lepra paucibacilar. Discusión. Pensamos que las diferencias halladas con otras poblaciones caucásicas reportadas por otros autores se deben a que la población chaqueña de origen caucásico tiene una fuerte mezcla con nativos de América del Sur, guaraníes y tobas (AU)

Objectives. Segregation analyses in several populations have suggested a relationship between specific human leukocyte antigen (HLA) class II alleles and the development of different types of leprosy. The aim of this study was to determine the frequency of HLA class II DR and DQ alleles among leprosy patients in Chaco province, northeast Argentina, in an effort to determine whether these alleles might be involved in the development of the multibacillary (MB) and paucibacillary (PB) forms of leprosy. Patients and methods. Samples from 89 leprosy patients (MB 5 70, PB 5 19) and 112 healthy control subjects were analyzed. The HLA-DRB1 and HLA-DQB1 alleles were determined by PCR amplification and reverse hybridization with sequence-specific oligonucleotide probes, and analyzed with the INNO-LiPA typing system and LiPA software. DQB1*0201/0202/0203 in patients with MB leprosy and DRB1*04 in patients with PB leprosy were detected at significantly lower frequencies as compared with the normal controls. Results. These data indicate that DQB1* 0201/0202/0203 may be a protective factor in MB leprosy and DRB1*04 in PB leprosy. Discusion. We attribute the differences between our findings and those of other authors to the fact that the Caucasian inhabitants of Chaco include a considerable mixture of South American natives (Guaraníes and Tobas) (AU)