ABSTRACT
An immunoperoxidase monolayer assay (IPMA) was adapted for the detection of antibodies to six arboviruses: three viruses within the flavivirus group (dengue 2, West Nile (WN) and yellow fever) and three in the phlebovirus group (Rift Valley fever (RVF), sandfly fever Naples and sandfly fever Sicilian). Antibody titers of homologous hyper-immune mouse ascitic fluid (HMAF) measured by IPMA were two to eight-fold less than those determined by ELISA. In tests with heterologous HMAF, cross-reactions frequently observed in ELISA, particularly in the flavivirus group, were absent in all IPMA titrations. With human serum samples tested for antibodies to RVF (n = 52) and WN (n = 90), the sensitivity of IPMA as compared with ELISA was 96 and 91%, respectively, specificity of IPMA was 100%. In addition, the IPMA format has several advantages that make it a useful alternative to ELISA for diagnosing arboviral infections under field conditions.
Subject(s)
Antibodies, Viral/blood , Arboviruses/immunology , Arbovirus Infections/blood , Arbovirus Infections/immunology , Arboviruses/chemistry , Cross-Sectional Studies , Enzyme-Linked Immunosorbent Assay , Flavivirus/chemistry , Flavivirus/immunology , Humans , Immunoenzyme Techniques , Immunoglobulin G/blood , Phlebovirus/chemistry , Phlebovirus/immunology , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
The effect of pH value, methanol, and salt concentration on the production of citric acid from cheese whey by two strains of Aspergillus niger, i.e. CAIM 111 and CAIM 167, was investigated. Lactose concentration, utilized lactose, citric acid concentration, conversion coefficient of lactose to citric acid, and mycelial dry weight were measured during the fermentation process. The maximum citric acid concentration (1.06 and 0.82 g/l), and conversion coefficient (5.58 and 7.45%) were obtained at pH 3.5 after 9 days of fermentation for A. niger CAIM 111 and A. niger CAIM 167, respectively. The presence of 4% (v/v) methanol in the fermentation medium increased the amount of citric acid produced by A. niger CAIM 111 and A. niger CAIM 167 by 23% and 18%, respectively. Both strains showed a high ability to utilize lactose for the production of citric acid when grown in the presence of 10% (w/v) salt. The conversion coefficient of lactose to citric acid was 28.24% for A. niger CAIM 111 and 25.60% for A. niger CAIM 167 when the fermentation medium had a 10% (w/v) level of salt. The cumulative effect of fermentation medium pH (3.5), methanol concentration (4%, v/v) and salt concentration (10%, w/v) during the fermentation process of whey did not enhance the production of citric acid by A. niger CAIM 111, while it did increase the production of citric acid by A. niger CAIM 167 by about 4-fold.
Subject(s)
Aspergillus niger/metabolism , Cheese , Citrates/metabolism , Fermentation , Aspergillus niger/drug effects , Citric Acid , Hydrogen-Ion Concentration , Methanol/pharmacology , Sodium Chloride/pharmacology , Species Specificity , Time FactorsABSTRACT
Seasonal variation of the population of aerobic sporeformers in raw milk was higher in summer than in other seasons. Least variation was in fall, but variation in winter and spring was similar. Aerobic mesophilic sporeformers in raw milk consisted mainly of Bacillus subtilis (42.5%) and Bacillus megaterium (34.8%), followed by Bacillus circulans (4.9%), Bacillus cereus (4.6%), Bacillus pumilus (2.9%), Bacillus polymyxa (2.8%), Bacillus licheniformis (1.9%), Bacillus badius (1.5%), Bacillus brevis (1.3%), Bacillus pulvifaciens (1.2%), Bacillus coagulans (1.1%), and Bacillus firmus (.5%). Comparing these findings with those previously obtained for the same area reveal noticeable variations. The psychrotrophic Bacillus strains were cereus (42.6%), pumilus (31.9%), badius (12.8%), licheniformis (10.6%), and firmus (2.1%).