Even with high reliability rates, these two phenotypic tests did not coincide with the molecular reference tests for the majority of the tested isolates: when the identification results by Biolog were compared to 16S rDNA gene sequencing and species-specific PCR reactions, 15 The different methods of evaluation provided different patterns of genera and species identification for the LAB isolates Table 1. Table 1 and 2. When the two phenotypic methods were compared to the sequencing results, the high frequency of non-coincident results is evident Tables 2. However, the remaining 13 isolates Differences between sequencing and phenotypic tests have already been observed previously, not just for LAB but also for many other bacteria Aymerich et al.
A Molecular Approach
Despite being the most reliable test, sequencing has some disadvantages. Aymerich et al. Considering the difficulties in differentiating between some LAB species with 16S rDNA sequencing and phenotypic tests 6, 12 , the application of specific molecular techniques such as species-specific PCR is necessary. For example, the identification of Enterococcus spp.
Speciesspecific PCR is also useful for identifying microorganisms at subspecies level, which cannot be easily achieved with other common techniques Beimfohr et al. Another disadvantage is the time required to obtain the sequencing results, which is considerably higher than the time needed to obtain phenotypic test results. The phenotypic tests are useful for identifying a small number of isolates, especially clinical samples, as their software databases mainly contain clinically important bacteria.
- Navigation menu?
- Bacterial Physiology: A Molecular Approach(Sie).
- Social Power and the Turkish State;
- Metacognition: Process, Function and Use.
- Bacterial Physiology: A Molecular Approach / Edition 1!
However, when using these methods their limitations must be considered, such as their poor reproducibility, a result of the plasticity of bacterial growth, the logistic difficulties for large-scale applications, and their sometimes poor discriminatory power Mohania et al. Another issue is that bacterial isolates do not express all their genes at the same time, as gene expression is related to environmental conditions.
A brief history of bacterial growth physiology
Considering this, the identification of such isolates only by biochemical tests can be jeopardized. In conclusion, the choice of identification method must be carefully analysed. Some factors must be considered, such as the origin of the samples food or clinical isolates , the number of isolates to be identified, and staff qualifications. For clinical samples, a phenotypic test could be used as a trial test, but the molecular methods are more accurate and should be used as confirmatory tests for hardto-identify isolates.
Considering that most of the LAB isolation and identification studies aim to detect potential biopreservative isolates from food, the molecular approach is probably the most sensitive. Appl Environ Microbiol Syst Appl Microbiol Compr Rev Food Sci Int Dairy J J Clin Microbiol Food Microbiol J Dig Dis Nishitani Y, Sasaki E, Fujisawa T, Osawa R Genotypic analyses of lactobacilli with a range of tannase activities isolated from human feces and fermented foods.
Foodborne Pathog Dis Annu Rev Microbiol Int J Food Microbiol While this has also raised a number of scientific mysteries about bacteria, it certainly improved our understanding of these organisms as complex and adaptive entities rather than just simple tiny buckets of enzymes. The value of this recent knowledge in bacterial physiology is not only restricted to fundamental biology, but it also extends to biotechnology and drug-discovery disciplines where understanding cell behaviour and structure is essential for better exploitation of useful bacteria and effective eradication of harmful ones.
- Services on Demand.
- Wicked Whispers.
- Pro Express.js Master Express.js The Node.js Framework For Your Web Development.
This makes a new text accommodating recent developments in bacterial physiology highly relevant to a wide range of readership including those interested in basic and applied knowledge. This monograph has collected many recent findings in the field and includes such topics as subcellular organization and function; regulation and expression of the genome, and cellular interaction with the environment via protein synthesis and secretion; intracellular signaling; and cellular adaptation.
- EEG Methods for the Psychological Sciences.
- Collected Stories (The Last Day of Windsor Forest & Calidore);
- The gastrointestinal system at a glance;