Efecto de la melaza de caña tratada con ácido sulfúrico en la producción de celulosa por Gluconacetobacter xylinus IFO 13693 / Effect of molasses cane treated with sulfuric acid in the production of cellulose by Gluconacetobacter xylinus IFO 13693 / Efeito do melaço de cana tratada com ácido sulfúrico na produção de celulose por Gluconacetobacter xylinus IFO 13693

En este estudio se evaluó el efecto de la melaza tratada con ácido sulfúrico (MZA-TR) y de las condiciones del cultivo (estático) sobre la síntesis de celulosa por Gluconacetobacter xylinus IFO 13693, para ello, se usó un reactor con 0,2 litros de medio de cultivo, con concentraciones iniciales de 13,3 % y 26,6 % de MZA-TR en el medio de cultivo a pH 5,6. El volumen del inóculo fue del 10 % del volumen total del medio; el proceso se realizó a temperatura ambiente (30 °C), con tiempos de incubación de 3, 7, 14, 21 y 28 días. Además, se evaluaron distintos parámetros fisicoquímicos y mecánicos de la celulosa. El grosor de la película de celulosa presentó un máximo de 2,5 cm, siendo el mejor resultado obtenido, en comparación con anteriores reportes en la literatura. También se encontró que al usar MZA-TR en el medio de cultivo hay un incremento considerable de la producción de celulosa en estático a los 28 días de incubación. Finalmente, se observó que el consumo de glucosa y de fructosa disminuye durante la síntesis de celulosa bacteriana (CB); durante los 3 primeros días de incubación se observó el máximo descenso, lo que permite correlacionar la producción de CB con el consumo de medio. La concentración de 13,3 %, presenta los mejores resultados en los parámetros de velocidad de crecimiento microbiano, cantidad y calidad de la celulosa producida.

This study assessed the effect of molasses treated with sulfuric acid (MZA-TR) and the condition of the crop (static) on the synthesis of cellulose by Gluconacetobacter xylinus IFO 13693, using a reactor with 0,2 liters of growing medium, with initial concentrations of 13,3 % and 26,6 % of molasses treated (MZA-TR) in the culture medium at pH 5,6. The volume of the inoculum was 10 per cent of the total volume of the environment; the process was carried out at ambient temperature (30 °C), with times of incubation of 3, 7, 14, 21 and 28 days. Also, different physico-chemical and mechanical parameters of the pulp were evaluated. The thickness of the cellulose film presented a maximum of 2.5 cm, being the best result obtained, in comparison to previous reports in the literature. Furthermore, it was found that using MZA-TR in the middle considerably increased the production of cellulose in static at 28 days of incubation. Finally, it was observed that the consumption of glucose and fructose decreased during the synthesis of Bacterial Cellulose (BC); during the first 3 days of incubation it was noted the maximum decline, which allows to correlate the production of CB with the consumption of media. The concentration of 13.3 %, presents the best results in the speed parameters of microbial growth, the quantity and quality of cellulose produced.

Neste estudo foi avaliado o efeito do melaço tratado com ácido sulfúrico (MZA-TR) e das condições da cultura (estática) sobre a síntese de celulose pelo Gluconacetobacter xylinus IFO 13693. Para isso, foi utilizado um reator com 0,2 litros de meio de cultura, com concentrações iniciais de 13,3 e 26,6% de MZA-TR, e pH igual a 5,6. O volume de inoculo foi de 10% do volume total do meio, e o processo foi realizado a temperatura ambiente (30°C), com tempos de 3, 7, 14, 21 e 28 dias. Além disso, foram avaliados os distintos parâmetros físico-químicos e mecânicos da celulose. A espessura máxima que apresentou o filme de celulose foi de 2,5 cm, sendo o melhor resultado obtido, ao comparar com os reportados anteriormente na literatura. Verificou-se também que ao usar MZA-TR no meio de cultura houve um aumento considerável na produção de celulose no meio estático aos 28 dias de incubação. Finalmente foi observado que o consumo de glicose e frutose diminuiu durante a síntese de celulose bacteriana (CB). Durante os três primeiros dias de incubação verificou-se a diminuição máxima, o que permite correlacionar a produção de CB com o consumo do meio. A concentração de 13,3% apresentou os melhores resultados nos parâmetros da velocidade de crescimento microbiano, quantidade e qualidade da celulose produzida.

Influence of different extracellular DNA levels in Staphylococccus epidermidis isolates on the ability of biofilm formation / 中华微生物学和免疫学杂志

ObjectiveTo determine the ability of biofilm formation of Staphylococcus epidermidis isolates and study the influence of different extracellular DNA(eDNA) levels in S.epidermidis isolates on the ability of biofilm formation.MethodsDetect the biofilm-formation ability of 227 S.epidermidis isolates with adhesion assays,amplify the icaA gene fragment with PCR.The S.epidermidis isolates were divided into biofilm formation(BF) group and non-biofilm formation (NBF) group according to adhesion assays and icaA amplification.Detect eDNA levels of S.epidermidis in planktonic culture and microtitre plate static culture.The eDNA in S.epidermidis biofilms stained by AO-PI was observed by CLSM.Results26 isolates were positive in adhesion assays and 32 isolates existed icaA gene among 227 S.epidermidis isolates.Select 20 isolates with positive adhesion assays and positive icaA amplification for BF group.Select 19 isolates with negative adhesion assays and negative icaA amplification for NBF group.The eDNA levels were (32.2±10.1)μg/ml,(33.6±11.9) μg/ml,(34.3±10.0) μg/ml in BF group when cultured in planktonic condition for 2,4,6 h,while the eDNA levels in NBF group were (28.7±8.9) μg/ml,(31.5±11.7) μg/ml,(31.8±12.7) μg/ml respectively.There were no significant differences between the two groups for these three phases(P＞0.05),though the eDNA levels of BF group were higher than that of NBF group.The eDNA levels were (740.0±264.4) ng/A600 in BF group when cultured in static microtitre plate,higher than that of NBF group,(80.1 ±31.1) ng/A600,and the difference between these two groups was significant.The eDNA in BF isolate Y36 biofilms could be visualized by staining with AO and PI when observed by CLSM,while neither biofilm structure nor eDNA appeard when NBF isolate Y26 was cultured for 24 h.ConclusionS.epidermidis isolates have the ability of biofilm formation.eDNA is one of the important matrix components in the S.epidermidis biofilm-forming process.The eDNA of static culture in microtitre plate was more efficient than planktonic culture in the case of estimating the ability of biofilm formation of S.epidermidis.

A simple way to improve fibroblast seeding efficiency and uniformity in constructing 3-D dermal equivalent / 第二军医大学学报

Objective:To explore a simple way to improve seeding efficiency and uniformity in constructing 3-D dermal equivalent,in order to effectively construct tissue engineered skin.Methods: Human dermal fibroblasts were added onto collagen sponge scaffolds and cultured in the following 3 ways:(1)oscillating seeding and oscillating culture(OO),(2)oscillating seeding and static culture(OS),and(3)static seeding and static culture (SS).Samples were obtained and subjected to light microscopy,scanning electron microscopy(SEM) and quantitative cell number assay at planed times.Results: Oscillating seeding achieved more uniform spatial cell distribution within scaffolds as compared to static seeding.Moreover,fibroblast seeding efficiency was significantly higher in oscillating conditions(\%) than in static conditions(\%,P