et al. (2001), using ARDRA as a fingerprinting method, also discovered that
microbial community composition in waters contaminated with TCE had shifted
towards a fairly diverse community dominated by Dehalococcoides ethenogeneslike microorganisms. Babalola et al. (2009) used ARDRA to study the phylogenetic
relationships of actinobacterial populations associated with Antarctic valley mineral
soils. Further sequencing of the amplicons restricted singly with endonucleases RsaI,
BsuRI, or AluI determined that the phylotypes were most closely related to
uncultured Pseudonocardia and Nocardioides spp. In contrast, complementary
traditionally established research had isolated more species of Streptomyces that
were detected at a low frequency in metagenomic analysis. ARDRA is useful in
detecting structural adjustments in microbial groups but cannot display microbial
variety or detect unique phylogenetic groups within a network fingerprinting profile
(Liu et al. 1997). Optimization with restriction enzymes is required, which frequently is difficult if sequences are unknown. Thus, further optimization can be
required to produce fingerprinting styles characteristic of the microbial community
(Vaneechoutte et al. 1995; Spiegelman et al. 2005). In addition, banding styles in
diverse groups appear to be too complicated to use ARDRA (Kirk et al. 2004). In
recent research, ARDRA has been blended with different molecular techniques
including T-RFLP and DGGE to signify microbial groups from contaminated
sources (Watts et al. 2001; Haack et al. 2004). An important assignment in the
usage of ARDRA lies within the interpretation of the fingerprints obtained from
complicated microbial communities.
5.9 Fluorescent In Situ Hybridization (FISH)
A critical step towards determining the variety of microbes in environmental samples
is to harness the statistics received from the direct sequencing of rRNA genes
extracted from such samples. The full-cycle rRNA method essentially makes use
of the series statistics of cloned, rRNA-encoding genes from environmental habitats
to broaden phylogenetic oligonucleotide probes that permit specific hybridization to
the goal region of the ribosomal RNA in constant permeabilized cells. Referred to as
fluorescent in situ hybridization (FISH) (Van Elsas et al. 2007), this is a speedy and
sensitive approach that allows the direct visualization and identity of environmental
microorganisms without culturing (Bakermans and Madsen 2002). Microbial cells
are penetrated with fixatives, hybridized with precise probes (generally 15- to 25-bp
oligonucleotide fluorescently labelled probes) on a tumbler slide, then visualized
with epifluorescence or confocal laser microscopy (Malik et al. 2008). Hybridization
with rRNA-targeted probes enhances the characterization of uncultured microorganisms and also enables the description of complicated microbial communities
(Edgcomb et al. 1999). FISH is a taxonomic approach used more often than not to
determine whether participants of a particular phylogenetic affiliation are present; it
offers direct visualization of uncultured microorganisms and also facilitates the
quantification of precise microbial organizations (Sanz and Kochling 2007). FISH
454
S. K. Shekhar et al.
microbial community composition in waters contaminated with TCE had shifted
towards a fairly diverse community dominated by Dehalococcoides ethenogeneslike microorganisms. Babalola et al. (2009) used ARDRA to study the phylogenetic
relationships of actinobacterial populations associated with Antarctic valley mineral
soils. Further sequencing of the amplicons restricted singly with endonucleases RsaI,
BsuRI, or AluI determined that the phylotypes were most closely related to
uncultured Pseudonocardia and Nocardioides spp. In contrast, complementary
traditionally established research had isolated more species of Streptomyces that
were detected at a low frequency in metagenomic analysis. ARDRA is useful in
detecting structural adjustments in microbial groups but cannot display microbial
variety or detect unique phylogenetic groups within a network fingerprinting profile
(Liu et al. 1997). Optimization with restriction enzymes is required, which frequently is difficult if sequences are unknown. Thus, further optimization can be
required to produce fingerprinting styles characteristic of the microbial community
(Vaneechoutte et al. 1995; Spiegelman et al. 2005). In addition, banding styles in
diverse groups appear to be too complicated to use ARDRA (Kirk et al. 2004). In
recent research, ARDRA has been blended with different molecular techniques
including T-RFLP and DGGE to signify microbial groups from contaminated
sources (Watts et al. 2001; Haack et al. 2004). An important assignment in the
usage of ARDRA lies within the interpretation of the fingerprints obtained from
complicated microbial communities.
5.9 Fluorescent In Situ Hybridization (FISH)
A critical step towards determining the variety of microbes in environmental samples
is to harness the statistics received from the direct sequencing of rRNA genes
extracted from such samples. The full-cycle rRNA method essentially makes use
of the series statistics of cloned, rRNA-encoding genes from environmental habitats
to broaden phylogenetic oligonucleotide probes that permit specific hybridization to
the goal region of the ribosomal RNA in constant permeabilized cells. Referred to as
fluorescent in situ hybridization (FISH) (Van Elsas et al. 2007), this is a speedy and
sensitive approach that allows the direct visualization and identity of environmental
microorganisms without culturing (Bakermans and Madsen 2002). Microbial cells
are penetrated with fixatives, hybridized with precise probes (generally 15- to 25-bp
oligonucleotide fluorescently labelled probes) on a tumbler slide, then visualized
with epifluorescence or confocal laser microscopy (Malik et al. 2008). Hybridization
with rRNA-targeted probes enhances the characterization of uncultured microorganisms and also enables the description of complicated microbial communities
(Edgcomb et al. 1999). FISH is a taxonomic approach used more often than not to
determine whether participants of a particular phylogenetic affiliation are present; it
offers direct visualization of uncultured microorganisms and also facilitates the
quantification of precise microbial organizations (Sanz and Kochling 2007). FISH
454
S. K. Shekhar et al.