Enterobacterial microflora in infancy - a case study with enhanced enrichment

Mixed Strain Fermentation and Metabonomics for Solving Issues of Bioproduction

In the research of mixed microbial cultures, the numbers and identifications of individual strains are often only partially unknown. Their metabolic capabilities are also not wholly predictable especially if the joint potential is to be understood. In these kinds of situations, deeper insight into the variable microbial communities cannot be obtained by genetic analysis only. Even more critical than the taxonomic aspect is usually the functional metabolic outcome of the mixed flora in question. The results from such studies as NMR (nucleic magnetic resonance) give a precise view from versatile angles into the biochemical activities during the multiparametric metabolic responses of the microflora as a whole.Originally, metabonomics was mainly used for the pathophysiological research of various microbes or for recording the genetic or biochemical modifications of mixed microflora. This approach offers a tool for monitoring changes in microscopic or otherwise confined ecosystems or at multiple locations from which representative specimens are difficult to obtain. It also offers repeatability in various processes. In microbiological studies, the research group can attain overall views on variable populations and their alterations in time and space.

Development of microbiological field methodology for water and food-chain hygiene analysis of Campylobacter spp. and Yersinia spp. in Burkina Faso, West Africa

Field-adaptable research methods for identifying Campylobacter sp., Yersinia sp. and other pathogenic and indicator bacteria were designed in Finland and tested in Burkina Faso. Several bacterial groups were also validated from artificially contaminated samples. Campylobacter strains were cultivated using an innovative gas generation system: The 'Portable Microbe Enrichment Unit' (PMEU) which provides microaerobic gas flow into the enrichment broth. This enhanced cultivation system produced rapid growth of several isolates of campylobacteria from water and chicken samples. The latter were obtained from local marketplace samples. No yersinias were found in the field studies, whereas they were readily recovered from the spiked samples, as well as Salmonella sp. and Escherichia coli strains. The PMEU method turned out to be reliable for monitoring of water and food hygiene in remote locations.

Enhanced recovery, enrichment and detection of Mycobacterium marinum with the Portable Microbe Enrichment Unit (PMEU)

The use of PMEU significantly accelerated the growth of otherwise slowly growing Mycobacterium sp. Compared to the static reference cultures, M. marinum was detected after 24-48h of cultivation in the PMEU Spectrion(®) equipped with infrared (IR) sensors. Parallel static cultures did not exhibit or indicate mycobacterial growth within these time limits, and essentially no growth was found in them. The PMEU approach could provide a powerful tool for the rapid diagnosis and determination of environmental and clinical isolates of slow-growing species of mycobacteria. This approach also provides a method for improving diagnostics for M. tuberculosis and other pathogenic mycobacteria, including their antibiotic resistant forms, which represents a significant health problem worldwide and in Africa in particular.

Enhanced mycobacterial diagnostics in liquid medium by microaerobic bubble flow in Portable Microbe Enrichment Unit

Portable Microbe Enrichment Unit (PMEU) method with microaerobic bubbling speeded up the growth of otherwise slowly starting and propagating Mycobacterium sp. Mycobacterium fortuitum growth was detected after 10-11h and Mycobacterium marinum produced clear growth in 4 days. A mycobacterial environmental isolate was verified in 2 days in the PMEU Spectrion(®) equipped with infrared sensors. In parallel static (without gas bubbling) cultures hardly any growth occurred. In conclusion, PMEU technology provided thus a rapid detection of environmental and clinical mycobacterial isolates. It would also help in the field diagnosis of antibiotic resistant Mycobacterium tuberculosis.

Fast coliform detection in portable microbe enrichment unit (PMEU) with Colilert(®) medium and bubbling

Laboratory strains of coliforms Escherichia coli and Klebsiella mobilis were used to artificially contaminate water samples in two different cultivation and detection systems, without and with bubble flow. Samples were collected with an automated system (ASCS). The positive coliform signal caused the color change into yellow (at 550-570nm). This signal could also be transmitted on-line to cell phones. E. coli containing samples emitted UV fluorescence at 480-560nm when activated by UV light. If cultivation was started with inocula varying from 10,000 to 1cfu/ml, the positive detection was obtained between 2 and 18h, respectively, in Colilert medium using Coline PMEU device without gas bubbling. Accordingly, a single K. mobilis cell produced detectable growth in 18h. Various clinical E. coli strains were compared to each other with equal inoculum sizes, and they showed slight variations in the initiation and speed of growth. The gas bubble flow in PMEU Spectrion promoted the mixing and interaction of bacteria and indicator media and speeded the onset of growth. Carbon dioxide also accelerated bacterial growth. In the presence of vancomycin, the onset of E. coli culture growth was speeded up by the volatile outlet flow from previous cultures. In the last cultivation syringe in a series of five, the lag phase disappeared and the growth of the inoculum continued without major interruption.

IN CONCLUSION

the stimulation of the cultures by the gas flow turned out to be a useful means for improving the detection of indicator bacteria. It could also be used in combination with antibiotic selection in the broth medium.