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    Review of 'Production and characterization of cyclodextrin glycosyltransferase from Bacillus.sp isolated from Cuban Soil.'

    Production and characterization of cyclodextrin glycosyltransferase from Bacillus.sp isolated from Cuban Soil.Crossref
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        Rated 4 of 5.
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    Production and characterization of cyclodextrin glycosyltransferase from Bacillus.sp isolated from Cuban Soil.

    A cyclodextrin glycosyltransferase (CGTase) from an alkaliphilic Bacillus.sp strain, isolated from Cuba soil, was purified with Sephadex G-50 with a yield of 66.5 %. The CGTase was stable over a very wide pH range, 6.0 –10, at 25°C and was most active at pH 7.5. The enzyme exhibited an optimum temperature of 60°C and was stable to 50°C for at least 8 h. The T50 value – defined as the temperature at which 50% of the initial activity was retained– was 63 °C in this enzyme . The influence of substrate or product concentration on the initial rate of CD production was studied and the kinetic parameters were determined. The analysis of kinetic parameters Km and Vmax was obtained by the action of CGTase on the starch of corn with respect to β-CD and the values were 4.1 g/L and 5,2 μM β-CD/min ml respectively.. The purified CGTase from Bacillus.sp could be used for an efficient cyclodextrin production which significant yield of γ-cyclodextrins.

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      Cyclodextrin glycosyltransferase, Bacillus.sp, Cuba soil, γ-cyclodextrins

      Review text

      My review expresses opinion of a physical chemist familiar with kinetics, thermodynamics and also with soil organic matter. Thus it is more review of a “generally interested reader” and not of an expert in biochemistry or biotechnology.

      The introduction briefly but clearly describes the state-of-the-art and clearly formulates the aim of published work. It really introduces readers and is not complicated by superfluous details. The work can be characterized as an application of established methods and approaches to isolate and test an important enzyme in pure form which would suppress the formation of byproducts in a reaction catalyzed by this enzyme. Thus, methodology is described in basics with references to further details. The experiments could be reproduced taking into account both the published and referenced works. Presentation and discussion of results correspond to the standard character of the aims and used methods. Interpretation of data is thus clear and straightforward; conclusions seem to be adequately supported by the data.

      Some more critical comments follow:

      • No information on reproducibility, replicates is given. Some figures show something like error bars while the other do not. The statistical significance and confidence of presented data cannot be assessed. For example, the significance of the two maxima discussed in Fig. 2.

      • I was rather confused by data shown in Fig. 1 and their commentary in the first paragraph of Results and Discussion section. Whereas the fractions 10-20 clearly have the highest absorbance, their activity is lower than activity of fractions 25-55; it is claimed that the former possessed the highest activity of all fractions.

      • In the same section the information on 66.5% activity is confusing – what is the base of 100%, in table 1 the same percentage is given for the yield.

      • Section CGTase production and purification introduces the notion of protein without explanation and clear reference to the enzyme. For example, is the enzyme the only protein, is there a protein mixture, if yes, what is the ratio of the desired product?

      • The last sentence on p.2 tells something about CD in the culture media – is this just an assumption or was the medium analyzed for the presence of CD?

      • There are no data showing the estimation of Michaelis-Menten parameters. Reader thus should just believe the given values and appropriateness of this model to measured kinetic data. More info (references) on the used software is missing.

      • I would welcome some details on soils used to isolate the bacterial strains. Was the isolation of the desired strain verified or just supposed?


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