Abstract
This study is the first comprehensive investigation of enzyme-producing bacteria isolated from four sludge samples (primary, secondary, press and machine) collected in a Kraft paper mill. Overall, 41 strains encompassing 11 different genera were identified by 16S rRNA gene analysis and biochemical testing. Both biodiversity and enzymatic activities were correlated with sludge composition. Press sludge hosted the largest variety of bacterial strains and enzymatic activities, which included hydrolytic enzymes and ligninolytic enzymes. In contrast, strains isolated from secondary sludge were devoid of several enzymatic activities. Most strains were found to metabolize Kraft liquor at its alkaline pH and to decolorize industrial lignin-mimicking dyes. Resistance to lignin or the ability to metabolize this substrate is a prerequisite to survival in any paper mill sludge type. We demonstrate here that the bacterial strains found in a typical Kraft paper mill represent a source of potential novel enzymes for both industrial applications and bioremediation.Electronic supplementary materialThe online version of this article (doi:10.1186/s40064-016-3147-8) contains supplementary material, which is available to authorized users.
Highlights
Industrial enzymes are at the heart of green chemistry as illustrated by a global market value that reached 5 G$ in 2013 which is expected to climb to 7 G$ by 2018, a compound annual growth rate of 8.2 % over 5 years (Global Markets for Enzymes in Industrial Applications; Nigam and Pandey 2009)
We have examined the readily cultivable bacterial community contained in Kraft paper mill sludge and assessed the potential of theses isolates for industrial enzymatic applications
Microbial diversity and enzyme secretion was partially dependent on the sludge composition, where certain genera were found to be specific to the type of sludge sampled
Summary
Industrial enzymes are at the heart of green chemistry as illustrated by a global market value that reached 5 G$ in 2013 which is expected to climb to 7 G$ by 2018, a compound annual growth rate of 8.2 % over 5 years (Global Markets for Enzymes in Industrial Applications; Nigam and Pandey 2009). Most industrial enzymes originate from microorganisms like Bacillus, Aspergillus and Trichoderma (Apparao and Krishnaswamy 2015; Arora and Sandhu 1985; Bengtsson et al 2006; Demain and Adrio 2008; Kubicek et al 2001; Liu et al 2013; Pandey et al 1999) These biocatalysts have found applications in various fields that depend on hydrolytic, ligninolytic and biosynthetic processes, to name a few (Barr and Steven 1994; Braunegg et al 2004; Chandra et al 2011; Martínez et al 2005; Nigam 2013). In recent years ligninolytic enzymes have been shown to be effective in industrial applications, including bio-remediation, pollution control and treatment of industrial effluents containing recalcitrant and hazardous chemicals such as textile dyes and or lignin mimicking dyes, phenols and other xenobiotic
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