spond to C-H stretching in -CH2 and –CH3 groups (usually
present in hexoses, like glucose or galactose, or deoxyhexoses
like rhamnose or fucose), suggests that we are dealing
with polymers, which are mainly composed of uronic acids.
Spectra from Melosira nummuloides and Navicula directa
exopolysaccharides are not shown because the spectral features
are very similar to those of Amphora holsatica.
In the first attempt to determine the exopolysaccharide
composition (neutral sugars and uronic acids), a short period
of acid hydrolysis (1 h) was applied. From the results obtained
with this hydrolysis, it was possible to demonstrate the
presence of neutral sugars and small amounts of uronic acids
(Table 3). Such findings were not in agreement with the
features from infrared spectroscopy, which revealed the existence
of large amounts of uronic acids. So, hydrolysis was
performed for a longer time (5 h), in order to detect the uronic
acids.
For the polymers isolated from the culture medium of
Amphora holsatica when a short-term hydrolysis was applied,
it was possible to identify the presence of rhamnose
(0.6 mg g–1), fucose (4.7 mg g–1), arabinose (2.6 mg g–1),
xylose (3.8 mg g–1) and glucose (3.8 mg g–1) and vestigial
amounts of uronic acids (Table 3). However, on analysing the
5 h acid hydrolysis results, an increase in rhamnose and
glucose content (4.3 and 4.7 mg g–1, respectively) and a
decrease in fucose, arabinose and xylose can be noted.
By the application of 1 h acid hydrolysis to the polymers
isolated from the culture medium of Melosira nummuloides,
spond to C-H stretching in -CH2 and –CH3 groups (usuallypresent in hexoses, like glucose or galactose, or deoxyhexoseslike rhamnose or fucose), suggests that we are dealingwith polymers, which are mainly composed of uronic acids.Spectra from Melosira nummuloides and Navicula directaexopolysaccharides are not shown because the spectral featuresare very similar to those of Amphora holsatica.In the first attempt to determine the exopolysaccharidecomposition (neutral sugars and uronic acids), a short periodof acid hydrolysis (1 h) was applied. From the results obtainedwith this hydrolysis, it was possible to demonstrate thepresence of neutral sugars and small amounts of uronic acids(Table 3). Such findings were not in agreement with thefeatures from infrared spectroscopy, which revealed the existenceof large amounts of uronic acids. So, hydrolysis wasperformed for a longer time (5 h), in order to detect the uronicacids.For the polymers isolated from the culture medium ofAmphora holsatica when a short-term hydrolysis was applied,it was possible to identify the presence of rhamnose(0.6 mg g–1), fucose (4.7 mg g–1), arabinose (2.6 mg g–1),xylose (3.8 mg g–1) and glucose (3.8 mg g–1) and vestigialamounts of uronic acids (Table 3). However, on analysing the5 h acid hydrolysis results, an increase in rhamnose andglucose content (4.3 and 4.7 mg g–1, respectively) and adecrease in fucose, arabinose and xylose can be noted.By the application of 1 h acid hydrolysis to the polymersisolated from the culture medium of Melosira nummuloides,
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