Restriction Fragment Length Polymorphism Analysis of 16S rRNA Genes in Lactic Acid Bacteria Isolated from Red Wine.

ABSTRACT The endophytic actinobacterial population in the roots of wheat grown in three different soils obtained from the southeast part of South Australia was investigated by terminal restriction fragment length polymorphism (T-RFLP) analysis of the amplified 16S rRNA genes. A new, validated approach was applied to the T-RFLP analysis in order to estimate, to the genus level, the actinobacterial population that was identified. Actinobacterium-biased primers were used together with three restriction enzymes to obtain terminal restriction fragments (TRFs). The TRFs were matched to bacterial genera by the T-RFLP Analysis Program, and the data were analyzed to validate and semiquantify the genera present within the plant roots. The highest diversity and level of endophytic colonization were found in the roots of wheat grown in a dark loam from Swedes Flat, and the lowest were found in water-repellent sand from Western Flat. This molecular approach detected a greater diversity of actinobacteria than did previous culture-dependent methods, with the predominant genera being Mycobacterium (21.02%) in Swedes Flat, Streptomyces (14.35%) in Red Loam, and Kitasatospora (15.02%) in Western Flat. This study indicates that the soil that supported a higher number of indigenous organisms resulted in wheat roots with higher actinobacterial diversity and levels of colonization within the plant tissue. Sequencing of 16S rRNA clones, obtained using the same actinobacterium-biased PCR primers that were used in the T-RFLP analysis, confirmed the presence of the actinobacterial diversity and identified a number of Mycobacterium and Streptomyces species.

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Formation of Pseudo-Terminal Restriction Fragments, a PCR-Related Bias Affecting Terminal Restriction Fragment Length Polymorphism Analysis of Microbial Community Structure

Applied and Environmental Microbiology ◽

10.1128/aem.69.5.2555-2562.2003 ◽

2003 ◽

Vol 69 (5) ◽

pp. 2555-2562 ◽

Cited By ~ 213

Author(s):

Markus Egert ◽

Michael W. Friedrich

Keyword(s):

Restriction Fragment Length Polymorphism ◽

16S Rrna ◽

Length Polymorphism ◽

Fragment Length Polymorphism ◽

Rflp Analysis ◽

Restriction Enzymes ◽

16S Rrna Genes ◽

Rrna Genes ◽

Restriction Fragments ◽

Restriction Fragment Length

ABSTRACT Terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR-amplified genes is a widely used fingerprinting technique in molecular microbial ecology. In this study, we show that besides expected terminal restriction fragments (T-RFs), additional secondary T-RFs occur in T-RFLP analysis of amplicons from cloned 16S rRNA genes at high frequency. A total of 50% of 109 bacterial and 78% of 68 archaeal clones from the guts of cetoniid beetle larvae, using MspI and AluI as restriction enzymes, respectively, were affected by the presence of these additional T-RFs. These peaks were called “pseudo-T-RFs” since they can be detected as terminal fluorescently labeled fragments in T-RFLP analysis but do not represent the primary terminal restriction site as indicated by sequence data analysis. Pseudo-T-RFs were also identified in T-RFLP profiles of pure culture and environmental DNA extracts. Digestion of amplicons with the single-strand-specific mung bean nuclease prior to T-RFLP analysis completely eliminated pseudo-T-RFs. This clearly indicates that single-stranded amplicons are the reason for the formation of pseudo-T-RFs, most probably because single-stranded restriction sites cannot be cleaved by restriction enzymes. The strong dependence of pseudo-T-RF formation on the number of cycles used in PCR indicates that (partly) single-stranded amplicons can be formed during amplification of 16S rRNA genes. In a model, we explain how transiently formed secondary structures of single-stranded amplicons may render single-stranded amplicons accessible to restriction enzymes. The occurrence of pseudo-T-RFs has consequences for the interpretation of T-RFLP profiles from environmental samples, since pseudo-T-RFs may lead to an overestimation of microbial diversity. Therefore, it is advisable to establish 16S rRNA gene sequence clone libraries in parallel with T-RFLP analysis from the same sample and to check clones for their in vitro digestion T-RF pattern to facilitate the detection of pseudo-T-RFs.

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Community Structure of Denitrifiers, Bacteria, and Archaea along Redox Gradients in Pacific Northwest Marine Sediments by Terminal Restriction Fragment Length Polymorphism Analysis of Amplified Nitrite Reductase (nirS) and 16S rRNA Genes

Applied and Environmental Microbiology ◽

10.1128/aem.67.4.1893-1901.2001 ◽

2001 ◽

Vol 67 (4) ◽

pp. 1893-1901 ◽

Cited By ~ 195

Author(s):

Gesche Braker ◽

Héctor L. Ayala-del-Rı́o ◽

Allan H. Devol ◽

Andreas Fesefeldt ◽

James M. Tiedje

Keyword(s):

Community Structure ◽

Restriction Fragment Length Polymorphism ◽

16S Rrna ◽

Fragment Length Polymorphism ◽

Puget Sound ◽

Rflp Analysis ◽

16S Rrna Genes ◽

Rrna Genes ◽

Restriction Fragment Length ◽

Redox Gradients

ABSTRACT Steep vertical gradients of oxidants (O2 and NO3 −) in Puget Sound and Washington continental margin sediments indicate that aerobic respiration and denitrification occur within the top few millimeters to centimeters. To systematically explore the underlying communities of denitrifiers,Bacteria, and Archaea along redox gradients at distant geographic locations, nitrite reductase (nirS) genes and bacterial and archaeal 16S rRNA genes (rDNAs) were PCR amplified and analyzed by terminal restriction fragment length polymorphism (T-RFLP) analysis. The suitablility of T-RFLP analysis for investigating communities of nirS-containing denitrifiers was established by the correspondence of dominant terminal restriction fragments (T-RFs) of nirS to computer-simulated T-RFs ofnirS clones. These clones belonged to clusters II, III, and IV from the same cores and were analyzed in a previous study (G. Braker, J. Zhou, L. Wu, A. H. Devol, and J. M. Tiedje, Appl. Environ. Microbiol. 66:2096–2104, 2000). T-RFLP analysis ofnirS and bacterial rDNA revealed a high level of functional and phylogenetic diversity, whereas the level of diversity ofArchaea was lower. A comparison of T-RFLPs based on the presence or absence of T-RFs and correspondence analysis based on the frequencies and heights of T-RFs allowed us to group sediment samples according to the sampling location and thus clearly distinguish Puget Sound and the Washington margin populations. However, changes in community structure within sediment core sections during the transition from aerobic to anaerobic conditions were minor. Thus, within the top layers of marine sediments, redox gradients seem to result from the differential metabolic activities of populations of similar communities, probably through mixing by marine invertebrates rather than from the development of distinct communities.

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