ABSTRACT
Combination of pretreatment with propidium monoazide by competitive polymerase chain reaction (cPCR) was evaluated to enumerate the viability of Salmonella spp. The results showed that PMA treatment was effective in preventing the cPCR detection of target sequences from non- viable cells. In less than 5 hrs, this method generated a signal from viable but nonculturable (VBNC) Salmonella spp. The standard culture method gave approximately 1-2 log(10)cfu ml(-1) less as compared to the PMA-cPCR results. These results provided evidence to support the VBNC state, whereas, the viable cells failed to be cultured by SCM. The proposed method did not detect DNA from dead Salmonella spp. but recognizes the infectious potential of the VBNC state and is thereby, able to assess the effect of control strategies and provide trustworthy data for risk assessment.
Subject(s)
Azides/chemistry , Polymerase Chain Reaction/methods , Propidium/analogs & derivatives , Salmonella/isolation & purification , Bacteriological Techniques , DNA, Bacterial/genetics , Propidium/chemistry , Reproducibility of Results , Salmonella/chemistry , Salmonella/geneticsABSTRACT
Indoor air pollution by airborne fungi has risen to become a common issue all over the world and it is hazardous to indoor occupants' health as it is associated with a series of respiratory-related and skin-related diseases. Selected bioactive compounds from the food industry have been suggested to be effective against individual fungus isolated from indoor environment. However, the techniques used to evaluate these compounds were lengthy and unsuitable against total airborne fungi. Therefore, this paper describes an assay to assess the effectiveness of a bioactive compound to inhibit growth of total airborne fungi.â¢A combination and modification of previous methods and the NIOSH Manual Analytical Standard Method (NMAM 0800) is proposed.â¢This method concurrently samples the total airborne fungi and evaluates the ability of bioactive compounds (potassium sorbate in this paper), as a biocide, to treat these indoor airborne fungi.â¢The current method shortens the time of evaluation from 30 days to only 5 days and employs the counting of colony forming units (CFUs) to ease the measurement of the growth of fungi.
