Subject(s)
Humans , Female , Adult , Carbamazepine/adverse effects , Stevens-Johnson Syndrome/etiology , Subcutaneous Absorption/drug effects , Anticonvulsants/adverse effects , Arm , Biopsy , Carbamazepine/administration & dosage , Stevens-Johnson Syndrome/surgery , Subcutaneous Tissue/surgery , Subcutaneous Tissue/pathology , Anticonvulsants/administration & dosageABSTRACT
Background: Currently, microbial fermentation method has become the research hotspot for acetoin production. In our previous work, an acetoin-producing strain, Bacillus subtilis SF4-3, was isolated from Japanese traditional fermented food natto. However, its conversion of glucose to acetoin was relatively low. In order to achieve a high-efficient accumulation of acetoin in B. subtilis SF4-3, main medium components and fermentation conditions were evaluated in this work. Results: The by-products analysis showed that there existed reversible transformation between acetoin and 2,3-butanediol that was strictly responsible for acetoin production in B. subtilis SF4-3. The carbon sources, nitrogen sources and agitation speed were determined to play crucial role in the acetoin production. The optimal media (glucose-H2O 150 g/L, yeast extract 10 g/L, corn steep dry 5 g/L, urea 2 g/L, K2HPO4 0.5 g/L, MgSO4 0.5 g/L) were obtained. Furthermore, the low agitation speed of 300 r/min was found to be beneficial to the reversible transformation of 2,3-butanediol for acetoin production in B. subtilis SF4-3. Eventually, 48.9 g/L of acetoin and 5.5 g/L of 2,3-butanediol were obtained in a 5-L fermenter, and the specific production of acetoin was 39.12% (g/g), which accounted for 79.90% of the theoretical conversion. Conclusions: The results indicated acetoin production of B. subtilis SF4-3 was closely related to the medium components and dissolved oxygen concentrations. It also provided a method for acetoin production via the reversible transformation of acetoin and 2,3-butanediol.
Subject(s)
Bacillus subtilis , Acetoin/metabolism , Butylene Glycols , Culture Techniques , Fermentation , Glucose , NitrogenABSTRACT
Streptococcus mutans is the primary pathogen responsible for initiating dental caries and decay
The presence of sucrose, stimulates S. mutans to produce insoluble glucans to form oral biofilm also known as dental plaque to initiate caries lesion
The GtfB and LuxS genes of S. mutans are responsible for formation and maturation of biofilm. Lactobacillus species as probiotic can reduces the count of S. mutans. In this study effect of different Lactobacillus species against the formation of S. mutans biofilm was observed
Growing biofilm in the presence of sucrose was detected using 96 well microtiter plate crystal violet assay and biofilm formation by S. mutans in the presence of Lactobacillus was detected. Gene expression of biofilm forming genes [GtfB and LuxS] was quantified through Real-time PCR
All strains of Lactobacillus potently reduced the formation of S. mutans biofilm whereas Lactobacillus acidophilus reduced the genetic expression by 60-80%
Therefore, probiotic Lactobacillus species can be used as an alternative instead of antibiotics to decrease the chance of dental caries by reducing the count of S. mutans and their gene expression to maintain good oral health.
ABSTRACT
The spatial and temporal variations of soil respiration were studied from May 2004 to June 2005 in a C3/C4 mixed grassland of Japan. The linear regression relationship between soil respiration and root biomass was used to determine the contribution of root respiration to soil respiration. The highest soil respiration rate of 11.54 micro mol m-2 s-1 was found in August 2004 and the lowest soil respiration rate of 4.99 micro mol m-2 s-1 was found in April 2005. Within-site variation was smaller than seasonal change in soil respiration. Root biomass varied from 0.71 kg m-2 in August 2004 to 1.02 in May 2005. Within-site variation in root biomass was larger than seasonal variation. Root respiration rate was highest in August 2004 (5.7 micro mol m-2 s-1) and lowest in October 2004 (1.7 micro mol m-2 s-1 ). Microbial respiration rate was highest in August 2004 (5.8 micro mol m-2 s-1 ) and lowest in April 2005 (2.59 micro mol m-2 s-1 ). We estimated that the contribution of root respiration to soil respiration ranged from 31% in October to 51% in August of 2004, and from 45% to 49% from April to June 2005.