83
other xenobiotics (Hofrichter et al. 2010; Lundell et al. 2010; Chandra et al. 2011;
Huber and Carre 2012; Marco-Urrea and Reddy 2012; Bansal and Kanwar 2013)
and have been recognised and recently reviewed.
Lignin peroxidase was isolated from a range of fungi. Versatile peroxidases are
very effective in the degradative transformation of compounds and they show
extraordinarily broad specificity. The peroxidase enzyme produces less soluble free
radicals and the precipitates can be removed by centrifugation and thus suggested
for decolorisation purposes. Peroxidases are seen in all groups of organisms with
various well-studied functions. In higher mammals they are involved in hormonal
regulation and defence activities. In plants they have roles in lignification, auxin
metabolism, etc. Microbial peroxidises are classified in to three types, viz., lignin
peroxidise, manganese peroxidise and versatile peroxidases.
3.3.4 Hydrolases
Hydrolases can reduce toxicity of compounds by degrading them. They bring about
condensation and alcoholysis. Their advantages include lack of stereospecificity,
easy availability and tolerance to addition of solvents. Polyaromatic hydrocarbons
are reported to be disrupted by these enzymes from a consortium (Balaji et al. 2014).
Chitinases are hydrolases and are considered as ideal candidates for acting as
biocontrol agents. Ihrmark et al. (2010) isolated and characterised chitinases from
Trichoderma harzianum, T. virens, T. atroviride and T. asperellum. Chitinases are
also produed by many bacterial species. Bacteria produces chitinases for utilising
chitin as a growth substrate. The recent increase in the occurrence of pathogenic
fungus has resulted in the accelerated search for novel antifungal agents like chitinases (Davies and Henrissat 1995; Bourne and Henrissat 2001). There are several
reports indicating the biocontrol activity of chitinase enzymes, which includes the
report on chitinase by Bacillus subtilis NPU 001 (Chang et al. 2010) They reported
that the purified chitinase inhibited hyphal extension of the fungus Fusarium oxysporum and showed potential activity against plant insects. Chitinase enzyme produced by a rhizosphere strain of Stenotrophomonas maltophilia strain MUJ showed
considerable thermal stability during 2 h incubation at 45 °C and inhibited the
growth of many fungal phytopathogens (Jankiewicz et al. 2012).
A purified chitinase chiIO8 from Bacillus cereus exhibited activity against
Botrytis cinerea in an in vivo assay and the result was reported by Hammami et al.
(2013). Bacillus subtilis JD- 09 was reported to restrict the growth of hyphae of
Fusarium oxysporum. The isolated enzyme was also active against the fungus and
exhibited high rates of chitin degradation (Velusamy and Das 2014). A 42-kDa
extracellular chitinase which is active at 40 °C and pH 4.6 was reported from a
entomopathogenic fungus Verticillium lecanii by Yu et al. (2015). The isolated
enzyme was examined for antagonistic activity against different phytopathogens
and could effectively resist their growth. The activity was observed to be strongly
influenced by the presence of Mg
2+
ions. Chitinases in the Trichoderma genus have
3 Enzymes for Bioremediation and Biocontrol
other xenobiotics (Hofrichter et al. 2010; Lundell et al. 2010; Chandra et al. 2011;
Huber and Carre 2012; Marco-Urrea and Reddy 2012; Bansal and Kanwar 2013)
and have been recognised and recently reviewed.
Lignin peroxidase was isolated from a range of fungi. Versatile peroxidases are
very effective in the degradative transformation of compounds and they show
extraordinarily broad specificity. The peroxidase enzyme produces less soluble free
radicals and the precipitates can be removed by centrifugation and thus suggested
for decolorisation purposes. Peroxidases are seen in all groups of organisms with
various well-studied functions. In higher mammals they are involved in hormonal
regulation and defence activities. In plants they have roles in lignification, auxin
metabolism, etc. Microbial peroxidises are classified in to three types, viz., lignin
peroxidise, manganese peroxidise and versatile peroxidases.
3.3.4 Hydrolases
Hydrolases can reduce toxicity of compounds by degrading them. They bring about
condensation and alcoholysis. Their advantages include lack of stereospecificity,
easy availability and tolerance to addition of solvents. Polyaromatic hydrocarbons
are reported to be disrupted by these enzymes from a consortium (Balaji et al. 2014).
Chitinases are hydrolases and are considered as ideal candidates for acting as
biocontrol agents. Ihrmark et al. (2010) isolated and characterised chitinases from
Trichoderma harzianum, T. virens, T. atroviride and T. asperellum. Chitinases are
also produed by many bacterial species. Bacteria produces chitinases for utilising
chitin as a growth substrate. The recent increase in the occurrence of pathogenic
fungus has resulted in the accelerated search for novel antifungal agents like chitinases (Davies and Henrissat 1995; Bourne and Henrissat 2001). There are several
reports indicating the biocontrol activity of chitinase enzymes, which includes the
report on chitinase by Bacillus subtilis NPU 001 (Chang et al. 2010) They reported
that the purified chitinase inhibited hyphal extension of the fungus Fusarium oxysporum and showed potential activity against plant insects. Chitinase enzyme produced by a rhizosphere strain of Stenotrophomonas maltophilia strain MUJ showed
considerable thermal stability during 2 h incubation at 45 °C and inhibited the
growth of many fungal phytopathogens (Jankiewicz et al. 2012).
A purified chitinase chiIO8 from Bacillus cereus exhibited activity against
Botrytis cinerea in an in vivo assay and the result was reported by Hammami et al.
(2013). Bacillus subtilis JD- 09 was reported to restrict the growth of hyphae of
Fusarium oxysporum. The isolated enzyme was also active against the fungus and
exhibited high rates of chitin degradation (Velusamy and Das 2014). A 42-kDa
extracellular chitinase which is active at 40 °C and pH 4.6 was reported from a
entomopathogenic fungus Verticillium lecanii by Yu et al. (2015). The isolated
enzyme was examined for antagonistic activity against different phytopathogens
and could effectively resist their growth. The activity was observed to be strongly
influenced by the presence of Mg
2+
ions. Chitinases in the Trichoderma genus have
3 Enzymes for Bioremediation and Biocontrol