expected at higher pH using alkaline active xylanases. Hemicellulases are also
important in waste management. In addition to agricultural and municipal solid
waste residues, different agro-industries, biorefineries, paper and pulp production
plants, etc. generate huge amounts of hemicellulose-containing waste. Therefore,
xylanases and mannanases can be used in managing such waste [162, 214]. This
avoids burning, release to aquatic bodies, or damping of hemicellulose-containing
waste, which makes it an environmentally sound method of disposal. Hemicellulases
have also been used to induce the synthesis of phytoalexins and acylated sterol
glycosides by tobacco cell suspension [215]. Moreover, xylanases have been successfully demonstrated in rhizosecretion of a target protein in simple hydroponic
medium [216] and also in making protoplasts [19]. In oil drilling, guar gum is used to
flood production wells to fracture the bedrock and enhance oil recovery. Reduction
of the viscosity by hydrolyzing the guar gum eases the oil flow. Due to the high
temperature and alkaline conditions of the wells, thermostable alkaline active
mannanases have been developed to reduce the polymer viscosity and improve oil
flow [217].
7 Conclusion
Several xylanases and mannanases have been studied and considered in a growing
number of applications. Applications such as detergent formulation, pulp
biobleaching, and textile fiber recovery and polymer (guar gum)-assisted oil recovery require enzymes which are active and stable in the alkaline range. This has led to
the search for alkaline active hemicellulases primarily from alkaliphiles. Indeed, a
variety of alkaline active hemicellulases have been purified and characterized from
alkaliphiles culture. Although the studies revealed the presence of very interesting
enzymes that are suitable for high pH applications, it seems that there has been very
little progress regarding the commercial utilization of alkaline active hemicellulases.
One of the reasons that possibly hinder the industrial application of these
extremozymes could be their limited availability in market. Commercial scale
development and production of alkaline active hemicellulases may facilitate wider
application of these enzymes in various sectors. Enzymes of alkaliphiles should not
be restricted only for high pH applications; there are many hemicellulases which are
significantly active in neutral to low pH conditions. The use of such enzymes in
non-alkaline applications should be encouraged, and this may contribute to their
commercialization.
A variety of hemicellulases are known to be involved in complete degradation of
hemicelluloses, and alkaliphiles are known to produce repertoire of these enzymes.
However, only xylanases and mannanases are attracting due attention. So far, very
little is known about the properties of other hemicellulases from alkaliphiles. Thus, it
would be very interesting to study these hemicellulases.
The economical, health, and environmental concerns associated with the use of
petroleum and its derivatives brought the campaign for utilization of biomass for
Alkaline Active Hemicellulases
279
important in waste management. In addition to agricultural and municipal solid
waste residues, different agro-industries, biorefineries, paper and pulp production
plants, etc. generate huge amounts of hemicellulose-containing waste. Therefore,
xylanases and mannanases can be used in managing such waste [162, 214]. This
avoids burning, release to aquatic bodies, or damping of hemicellulose-containing
waste, which makes it an environmentally sound method of disposal. Hemicellulases
have also been used to induce the synthesis of phytoalexins and acylated sterol
glycosides by tobacco cell suspension [215]. Moreover, xylanases have been successfully demonstrated in rhizosecretion of a target protein in simple hydroponic
medium [216] and also in making protoplasts [19]. In oil drilling, guar gum is used to
flood production wells to fracture the bedrock and enhance oil recovery. Reduction
of the viscosity by hydrolyzing the guar gum eases the oil flow. Due to the high
temperature and alkaline conditions of the wells, thermostable alkaline active
mannanases have been developed to reduce the polymer viscosity and improve oil
flow [217].
7 Conclusion
Several xylanases and mannanases have been studied and considered in a growing
number of applications. Applications such as detergent formulation, pulp
biobleaching, and textile fiber recovery and polymer (guar gum)-assisted oil recovery require enzymes which are active and stable in the alkaline range. This has led to
the search for alkaline active hemicellulases primarily from alkaliphiles. Indeed, a
variety of alkaline active hemicellulases have been purified and characterized from
alkaliphiles culture. Although the studies revealed the presence of very interesting
enzymes that are suitable for high pH applications, it seems that there has been very
little progress regarding the commercial utilization of alkaline active hemicellulases.
One of the reasons that possibly hinder the industrial application of these
extremozymes could be their limited availability in market. Commercial scale
development and production of alkaline active hemicellulases may facilitate wider
application of these enzymes in various sectors. Enzymes of alkaliphiles should not
be restricted only for high pH applications; there are many hemicellulases which are
significantly active in neutral to low pH conditions. The use of such enzymes in
non-alkaline applications should be encouraged, and this may contribute to their
commercialization.
A variety of hemicellulases are known to be involved in complete degradation of
hemicelluloses, and alkaliphiles are known to produce repertoire of these enzymes.
However, only xylanases and mannanases are attracting due attention. So far, very
little is known about the properties of other hemicellulases from alkaliphiles. Thus, it
would be very interesting to study these hemicellulases.
The economical, health, and environmental concerns associated with the use of
petroleum and its derivatives brought the campaign for utilization of biomass for
Alkaline Active Hemicellulases
279