Surface Modification of Cellulose Acetate with Cutinase and ...

Chapter 1
filamentous fungal and bacterial sources are the most used in industrial sectors (Pandey
et al., 2000).
Molecular weights of microbial α-amylases range from 50 to 60 KDa, with few
exceptions, like a 10 KDa α-amylase from Bacillus caldolyticus and a 210 KDa α-
amylase from Chloroflexus aurantiacus (Grootegoed et al., 1973; Ratanakhanokchai et
al., 1992). α-Amylases from most bacteria and fungi are quite stable over a wide range
of pH from 4 to 11. Alicyclobacillus acidocaldarius α-amylase present an acidic pH
optima of 3 in contrast to α-amylases from several alkalophilic and extreme alkalophilic
Bacillus sp. with pH optima of 9 to 10.5 and 11 to 12, respectively (Schwermann et al.,
1994; Krishnan and Chandra, 1983; Lee et al., 1994; Kim et al., 1995).
Optimum temperature for the activity of α-amylases is also related to the growth of the
producer microorganism (Vihinen and Mantsala, 1989). Temperatures from 25 to 30 ºC
were reported for Fusarium oxysporum α-amylase (Chary and Reddy, 1985) and higher
temperatures of 100 and 130 ºC for Pyrococcus furiosus and Pyrococcus woesei,
respectively (Laderman et al., 1993; Koch et al., 1991).
Addition of Ca 2+ can, in some cases, enhance α-amylases thermostability (Vihinen and
Mantsala, 1989; Vallee et al., 1959). They are extremely inhibited by heavy metal ions,
sulphydryl group reagents, EDTA and EGTA (Mar et al., 2003; Tripathi et al., 2007).
In general microbial α-amylases display highest specificity towards starch followed by
amylase, amylopectin, cyclodextrin, glycogen and maltotriose (Vihinen and Mantsala,
1989).
4.1 Textile Desizing
Amylases are the most successful enzymes used in textile industry for desizing. For
fabrics made from cotton or blends, the warp threads are coated with an adhesive
substance know as “size” to lubricate and protect the yarn from abrasion preventing the
threads to break during weaving. Although many different compounds have been used
to size fabrics, starch and its derivatives have been the most common sizing agents
because of their excellent film forming capacity, availability, and relatively low cost
(Feitkenhauer et al., 2003).
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