Biology Reference
In-Depth Information
The
BM
and
GC
had a G + C content of 59.5 and 61.7 M%, respectively (Table 1),
whereas ALT-92T presented 63.2 M%. On the basis of the
ad hoc
committee recom-
mendations [16, 17] of a threshold value of 70% DNA-DNA similarity for the defi ni-
tion of bacterial species, the two strains formed an homogeneous cluster with a high
degree of internal similarity (DNA-DNA similarity > 90.5%) and should be consid-
ered as members of the same
H. tebenquichense
species.
The random amplifi ed polymorphic DNA (RAPD) or arbitrarily primed poly-
merase chain reaction (AP-PCR) DNA fi ngerprinting technique provides one of the
most sensitive and effi cient of current methods for distinguishing different strains of
a species [18]. In order to corroborate such differences between the two isolates, AP-
PCR fi ngerprint analysis was performed (Figure 1). The band pattern showed vis-
ible differences between
BM
and
GC
fi ngerprint (absence or presence of 2, 4, 6 and
7 bands), in concordance with biochemical tests and 16S rDNA sequence data. In
sum, differences in fructose metabolism, utilization of starch and optimum growth
conditions (Table 1), together with those revealed by the AP-PCR, suggested that
BM
and
GC
isolates were different not only from those described for
H. tebenquichense
ALT-92 T [15], but also between each other and could be classifi ed as new
H.
tebenquichense
strains.
Figure 1.
The AP-PCR finger print DNA analysis. Lane 1: Ladder 100 pb -PB-L, Lane 2: negative
control, Lane 3:
H. tebenquichense
, Lane 4:
BM
, Lane 5:
GC
, Lane 6:
E. coli.
Lipid Extraction and Characterization
The TPL, defined as the acetone insoluble portion of the total lipids, extracted from fro-
zen cells obtained from a batch of 8 l, ranged between 90 and 120 mg for each isolate.
A high content of phosphate groups is reported in the literature for the
Halorubrum
genus. Hence, for TPL quantifi cation two colorimetric methods were applied: one,
for detecting total phosphate (Bötcher) and the other for detecting organic phosphate
