This study was focused on the enzymes produced by bacteria, symbiotically living in termite gut. To find the role of bacteria playing in hemicelluloses digestion in this biologically assorted mini-biorefinery [20]. During the research facultative anaerobic and aerobic xylanolytic bacterial isolates were studied from termite gut. It was premeditated that the gut of termite has anaerobic surroundings [21], whereas anaerobic and aerobic bacteria were also isolated [22] from termite gut. After congo red screening two bacterial isolates were selected because they illustrate a significant xylanase activity with xylan.
From molecular characterization of the selected isolates it was found that both of them belong to Bacillus geneus. Commonly, enormous of celluloytic and xylanolytic microaerophilic and facultative anaerobic bacteria inhabit in termite gut. But species of Bacillus genera predominate with concentration up to 107/ml gut content [22]. Bacillus species are ubiquitous in environment and include symbiotically associated and free-living species. Majority among them are efficiently active and involved in a series of wood degrading enzymes like laccase, cellulase, amylase, xylanase, hemicellulase, ligninase [23]. A study reported that Bacillus and Acinetobacter have dominant biomass degrading ability from other isolates belonged to Microcerotermes diversus [24]. Bacillus species were described to be the leading lignocelluloses devastating bacterial isolates collected from soil and animal waste samples, as well as from paper mills sludges [25].
Maximum xylanase activity was observed at 50 oC for the bacterial isolates. During a research it was studied that most favorable temperature for xylanase activity was 50 oC from a Bacillus sp. obtained from soil [26]. During experimentation it was oberseved that isolate TGB9 and TGB10 showed highest xylanase activity at pH 6.0. purified two xylanases from Bacillus sp. namely xylanases N and xylanase A. Xylanase N showed highest activity at pH 6.0 and 7.0, whereas xylanase A showed best results at pH 6.0–10.0. But a study reported that gram positive bacteria from termite gut showed maximum xylanase activity, pH 5.0 at 55 oC [27].
The xylanases produced by TGB9 and TGB10 released highest sugar content when corn stover was used as substrate as compared to cotton stalk and rice straw. Although, the carbohydrate content is high in rice straw (mannose, xylose, glucose, etc) as compared to the corn stover [28]. But it was also determined that minerals content are high in rice straw [29] which slowed degradation of rice straw in soil. A study showed that xylanase activity was improved by using reducing agents. But chelating agents, such as detergents and Cu2+ decreased xylanase activity. High mineral content of hinder the activity of these enzymes, but do not hinder the chemicals (H2SO4 and NaOH) pretreatment [30]. Therefore, chemical pretreatment released nearly the same concentration of sugar content during pretreatment of rice straw. Least sugar content is released from cotton stalk compared to other agricultural substrates. It was studied that lignin content are high in cotton stalk therefore it is hard to hydrolyze [31]. It was also observed that when concentration of acid was increased the sugar yield was decreased. It was verified that at acidic conditions, as sugar released some of it is changed to inhibitors such as hydroxymethyl furfural and furfural [32]. So as the concentration of acid increase concentration of inhibitors elevate. Therefore absolutely decrease concentration of sugar content.