Enzyme promiscuity can be classified into substrate promiscuity, condition promiscuity and catalytic promiscuity. Enzyme promiscuity results in far larger ranges of organic compounds which can be obtained by biocatalysis. While early examples mostly involved use of lipases, more recent literature shows that catalytic promiscuity occurs more widely and many other classes of enzymes can be used to obtain diverse kinds of molecules. This is of immense relevance in the context of white biotechnology as enzyme catalysed reactions use greener conditions.
The effect of incubation temperature on acid and flavor production by 8 lactic starter cultures was studied. Higher titratable acidity was produced at 22 than at 30 C by Streptococcus cremoris, while a reverse trend was observed with Streptococcus diacetilactis. With Streptococcus thermophilus, Lactobacillus casei, and Lactobacillus helveticus, increasing the incubation temperature from 37 to 42 C retarded acid production by 8.54, 31.8, and 37.4%, respectively. Volatile acidity increased at higher incubation temperatures in some cultures, while in others, a significant decrease was observed. Higher diacetyl production was noted when S. diacetilactis was incubated at 22 C, as compared to 30 C, while the reverse occurred with S. thermophilus. Acetoin production by S. diacetilactis was enhanced 7-fold by increasing the incubation temperature from 22 to 30 C. No significant difference was noted in proteolytic activity of all cultures, regardless of incubation temperature.
Glucose fatty acid esters were synthesized using cross-linked enzyme aggregates (CLEAs), protein
coated microcrystals (PCMCs) and cross-linked protein coated microcrystals (CLPCMCs) of Candida
antarctica lipase B (CALB) as biocatalyst designs in single and mixed solvent systems. Up to 90%
conversion and more than 99% regioselectivity were obtained using vinyl acetate as the acyl donor in
a solvent system composed of 2-methyl-2-butanol (2M2B) and 30% (v/v) DMSO, with CALB CLEAs
within 45 min. Similar results were obtained with CALB CLPCMCs as the biocatalyst under the same
reaction conditions. This approach was then extended to the synthesis of glucose esters with higher
acyl chain length. The synthetic strategy used in this work can potentially be extended for the fast and
regioselective esterification/transesterification of other sugars as well.
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