Diseño de un medio de cultivo para la producción de biomasa de Microbacterium sp. (BSC3) para la generación de materia orgánica humificada a partir de lignito / Design of culture medium for biomass production of Microbacterium sp. (BSC3) to the humified organic matter generation from lignite

RESUMEN Se diseñó un medio de cultivo para la multiplicación de una cepa bacteriana solubilizadora de carbón (BSC3). Como sustratos se utilizaron tres residuos agroindustriales: melaza de caña, lactosuero y cabecilla de arroz. Mediante diseños de superficie de respuesta Box-Behnken se evaluaron dos rangos de concentraciones para cada sustrato (2-10% y 0-6%). De esta forma se obtuvo la combinación adecuada para la producción de biomasa de BSC3. Se construyeron curvas de crecimiento bacteriano para determinar algunos parámetros cinéticos (velocidad específica de crecimiento [u], tiempo de duplicación [Td] y producción final de biomasa), que fueron comparados con el crecimiento de la cepa en un medio de cultivo control, también se caracterizó elementalmente (CHN) el medio optimizado. Las concentraciones óptimas para la obtención de biomasa de BSC3 fueron: 6% melaza, 2,5% lactosuero más un contenido mínimo de sales, con un pH de 6,5. Los parámetros cinéticos en este medio fueron: biomasa final=3,2 g.L-1, u=0,0206 h-1, Td=33,64 h, y en el medio control: biomasa final=3,4 g.L-1, u=0,0139 h-1, Td=49,85 h, lo cual muestra que el medio permitió un incremento en la velocidad de crecimiento y un menor tiempo de duplicación de BSC3, de esta forma el medio optimizado permitió la multiplicación de BSC3 y le permitió conservar su actividad solubilizadora de carbón.

ABSTRACT A culture medium for the multiplication of a coal solubilizing bacterial strain was designed (BSC3); were used three agroindustrial wastes: cane molasses, whey and crushed rice. Through Box-Behnken surfaces responses designs, two concentration ranks (2-10% y 0-6%) were evaluated, so the adequate combination to BSC3 biomass production was found. Bacterial growth curves were constructed to determine some kinetics parameters (growth specific rate [u], duplication time [Dt] and biomass final production), that were compared with the strain growth in a control culture medium; the optimized culture medium was also elementally caracterizated. The optimal concentrations to BSC3 biomass obtaining were: 6% molasses cane, 2,5% whey plus a salts minimum medium, with pH of 6,5. The kinetics parameters in this medium were: final biomass = 3,2 g.L-1, u=0,0206 h-1, Dt=33,64 h, and in the control medium: final biomass = 3,4 g.L-1, u=0,0139 h-1, Dt=49,85 h, this shows that the optimized medium allows the increase of the specific growth rate and a less duplication time of BSC3, so the optimized medium allowed to conserve its coal solubilizing activity.

Characterization of Bacteria Community Isolated from Wood Decay.

In order to discover enzymes having potential for wood fibre modification, bacteria (fourteen strains designated MMB1 to MMB14) were isolated from a decomposing stump from a resinous tree. Phylogenetic analysis and biochemical characterization indicated that these isolates were related to Microbacterium, Chryseobacterium, Lysinibacillus, and Bacillus gene; although most demonstrated phenotypic differences compared to previously characterized relatives. Only the Bacillus strains showed cellulolytic activity (as CMCase detected with Congo red) and only Bacillus subtilis strains (MMB10 to MMB14) displayed cellulolytic and secreted xylanase activity. Phenotypic characterization of two strains (MMB8 and MMB9) related to a previously characterized isolate (Bacillus sp. JU2), supported their reassignment to the genus Lysinibacillus. The Microbacterium strain MMB1 produced a green pigment when grown in the presence of light. Some microbes from the consortium were devoid of wood polymer modifying enzymes, and may be dependent on other organisms for their survival in this biotope.

Carbazole degradation in the soil microcosm by tropical bacterial strains

In a previous study, three bacterial strains isolated from tropical hydrocarbon-contaminated soils and phylogenetically identified as Achromobacter sp. strain SL1, Pseudomonas sp. strain SL4 and Microbacterium esteraromaticum strain SL6 displayed angular dioxygenation and mineralization of carbazole in batch cultures. In this study, the ability of these isolates to survive and enhance carbazole degradation in soil were tested in field-moist microcosms. Strain SL4 had the highest survival rate (1.8 x 107 cfu/g) after 30 days of incubation in sterilized soil, while there was a decrease in population density in native (unsterilized) soil when compared with the initial population. Gas chromatographic analysis after 30 days of incubation showed that in sterilized soil amended with carbazole (100 mg/kg), 66.96, 82.15 and 68.54% were degraded by strains SL1, SL4 and SL6, respectively, with rates of degradation of 0.093, 0.114 and 0.095 mg kg−1 h−1. The combination of the three isolates as inoculum in sterilized soil degraded 87.13% carbazole at a rate of 0.121 mg kg−1 h−1. In native soil amended with carbazole (100 mg/kg), 91.64, 87.29 and 89.13% were degraded by strains SL1, SL4 and SL6 after 30 days of incubation, with rates of degradation of 0.127, 0.121 and 0.124 mg kg−1 h−1, respectively. This study successfully established the survivability (> 106 cfu/g detected after 30 days) and carbazole-degrading ability of these bacterial strains in soil, and highlights the potential of these isolates as seed for the bioremediation of carbazole-impacted environments.

Production of humic substances through coal-solubilizing bacteria

In this paper, the production of humic substances (HS) through the bacterial solubilization of low rank coal (LRC) was evaluated. The evaluation was carried out by 19 bacterial strains isolated in microenvironments with high contents of coal wastes. The biotransformed LRC and the HS produced were quantified in vitro in a liquid growth medium. The humic acids (HA) obtained from the most active bacterial strain were characterized via elemental composition (C, H, N, O), IR analyses, and the E4/E6 ratio; they were then compared with the HA extracted chemically using NaOH. There was LRC biotransformation ranged from 25 to 37%, and HS production ranged from 127 to 3100 mg.L-1. More activity was detected in the isolated strains of Bacillus mycoides, Microbacterium sp, Acinetobacter sp, and Enterobacter aerogenes. The HA produced by B. mycoides had an IR spectrum and an E4/E6 ratio similar to those of the HA extracted with NAOH, but their elemental composition and their degree of aromatic condensation was different. Results suggest that these bacteria can be used to exploit the LRC resulting from coal mining activities and thus produce HS in order to improve the content of humified organic matter in soils.

A Case of Bacteremia Due to Microbacterium oleivorans Identified by 16S rRNA Sequencing Analysis / 대한임상미생물학회지

Microbacterium oleivorans is a gram-positive, coryneform rod bacterium. The pathogenic potential of the Microbacterium species has recently been reported to be increasing. Microbacterium comprises approximately 50 species. The differences in regards to the biochemical characteristics of Microbacterium species are unclear, and is why molecular investigations (e.g., using 16S rRNA gene sequencing) are the best method to identify the species. We report a case of bacteremia that was caused by Microbacterium oleivorans in a 4-year-old boy, who had no specific medical history. This represents the first report of M. oleivorans bacteremia in Korea.

Bioemulsifier production by Microbacterium sp. strains isolated from mangrove and their application to remove cadmiun and zinc from hazardous industrial residue

The contamination of ecosystems with heavy metals is an important issue in current world and remediation technologies should be in according to environmental sustainability concept. Bioemulsifier are promising agents to be used in metal removal and could be effective to many applications in environmental industries. The aims of this work was screening the potential production of bioemulsifier by microorganisms isolated from an oil contaminated mangrove, and evaluate cadmium and zinc removal potential of those strains from a hazardous industrial residue. From that, bioemulsifier-producing bacteria were isolated from urban mangrove sediments. Four isolates were identified as Microbacterium sp by 16S rRNA analysis and were able to reduce up to 53.3 percent of culture medium surface tension (TS) when using glucose as carbon and energy source and 20.2 percent when sucrose was used. Suspensions containing bioemulsifier produced by Microbacterium sp. strains show to be able to remove cadmium and zinc from contaminated industrial residue, and its ability varied according carbon source. Significant differences in metal removal were observed by all strains depending on the carbon source. When glucose was used, Cd and Zn removal varied from 17 to 41 percent, and 14 to 68 percent, respectively. However, when sucrose was used it was observed only 4 to a maximum of 15 percent of Cd removal, and 4 to 17 percent of Zn removal. When the same tests were performed after ethanol precipitation, the results were different: the percentages of removal of Zn (7-27 percent) and Cd (14-32 percent) were higher from sucrose cultures. This is the first report of heavy metals removal by bioemulsifier from Microbacterium sp.

Catheter-related Bacteremia due to Microbacterium oxydans Identified by 16S rRNA Sequencing Analysis and Biochemical Characteristics / 대한임상미생물학회지

Microbacterium oxydans, a coryneform gram-positive bacillus, have been isolated from a wide variety of environmental sources and reported its pathogenic potential with increasing frequency in the last few years. Microbacterium comprises more than 60 species. 16S rRNA sequences in different Microbacterium species are highly conserved and the differences of biochemical characteristics between several species are unclear. As a result, identification of Microbacterium to species level has been difficult in most clinical microbiology laboratories. In this article, we report a case of catheter-related bacteremia caused by M. oxydans that was identified by 16S rRNA sequencing analysis and phenotypic characteristics in patient with diffuse large B-cell lymphoma.

Central Venous Catheter-Related Microbacterium Bacteremia Identified by 16S ribosomal RNA Gene Sequencing / 대한임상미생물학회지

We describe here a case of central venous catheter (CVC)-related bacteremia caused by Microbacterium species in a 14-year-old patient, who had received chemotherapy for acute lymphoblastic leukemia. All nine blood cultures obtained from admission day 2 to day 62 yielded the same yellow-pigmented coryneform rod. Both Vitek 2 (bioMerieux, USA) and MicroScan (Dade Behring, USA) identified the isolate as Micrococcus species, and the API Coryne (bioMerieux, France) identified the isolate as Rhodococcus or Brevibacterium species. However, the 16S rRNA gene sequence showed a 99% identity with Microbacterium species. The bacteremia was recurrent or persistent over 60 days despite alternate systemic antibiotic therapy, but blood culture became negative after an addition of teicoplanin lock therapy for eradicating CVC-related bacteremia. This represents the first report of CVC-related Microbacterium bacteremia cured by antibiotic lock therapy in Korea.

Condition of p-nitroaniline Degrading Microbacterium sp. PNA8 and Its Degradation of p-nitroaniline / 微生物学通报

A bacterial strain capable of utilizing p-nitroaniline as sole carbon source to growth was isolated from sewage sludge. This strain was identified as Microbacterium sp. PNA8 based on its morphology, physiological, biochemical properties and 16S rRNA sequence analysis. Results indicated that the optimal temperature and pH for cell growth and for p-nitroaniline degradation was 30?C and 7.0. Strain PNA8 growth and p-nitroaniline degradation was considerably faster in the presence of yeast extract. Optimum conditions, in the culture medium added to 0.4 g/L yeast extract, 0.3 mmol/L p-nitroaniline degradation rate to 100% in 4 days.

A case of native valve infective endocarditis caused by Microbacterium species / 대한내과학회지

Microbacterium species is part of the normal flora of the skin and pharynx. Native valve infective endocarditis caused by Microbacterium speciesis is rare case. We describe a 37-year-old man with native valve endocarditis caused by Microbacterium species. He presented with high fever, myalgia, weight loss. Microbacterium species was isolated from blood culture. Successful treatment was achieved with intravenous ceftriaxone and oral amoxicillin.