Background. Polyhydroxyalkanoates (PHAs) are storage materials that accumulate by various bacteria as energy and carbon reserve materials. They are biodegradable, environmentally friendly, and also biocompatible bioplastics. Unlike petrochemical-based plastics that take several decades to fully degrade, PHAs can be completely degraded within a year by variety of microorganisms into CO2 and water. In the present study, we aim to utilize pulp, paper, and cardboard industry sludge and waste water for the isolation and screening of polyhydroxyalkanoates (PHAs) accumulating bacteria and production of cost-effective PHB using cardboard industry waste water. Results. A total of 42 isolates showed black-blue coloration when stained with Sudan black B, a preliminary screening agent for lipophilic compounds, and a total of 15 isolates showed positive result with Nile blue A staining, a more specific dye for PHA granules. The isolates NAP11 and NAC1 showed maximum PHA production 79.27% and 77.63% with polymer concentration of 5.236 g/L and 4.042 g/L with cardboard industry waste water. Both of the selected isolates, NAP11 and NAC1, were classified up to genus level by studying their morphological and biochemical characteristics and were found to be Enterococcus sp., Brevundimonas sp. and, respectively. Conclusion. The isolates Enterococcus sp. NAP11 and Brevundimonas sp. NAC1 can be considered as good candidates for industrial production of PHB from cardboard industry waste water. We are reporting for the first time the use of cardboard industry waste water as a cultivation medium for the PHB production.

Background: In the present study, we aim to utilize the ecological diversity of soil for the isolation and screening for poly β-hydroxybutyrate (PHB)-accumulating bacteria and production of cost-effective bioplastic using cardboard industry effluent. Results: A total of 120 isolates were isolated from different soil samples and a total of 62 isolates showed positive results with Nile blue A staining, a specific dye for PHB granules and 27 isolates produced PHB using cardboard industry effluent. The selected isolate NA10 was identified as Bacillus sp. NA10 by studying its morphological, biochemical, and molecular characteristics. The growth pattern for the microorganism was studied by logistic model and exactly fitted in the model. A maximum cell dry weight (CDW) of 7.8 g l −1 with a PHB concentration of 5.202 g l −1 was obtained when batch cultivation was conducted at 37°C for 72 h, and the PHB content was up to 66.6% and productivity was 0.072 g l −1 h −1 in 2.0 L fermentor. Chemical characterization of the extracted PHB was done by H 1 NMR, Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), Gas chromatography-mass spectrometry (GC-MS) analysis to determine the structure, melting point, and molecular mass of the purified PHB. The polymer sheet of extracted polymer was prepared by blending the polymer with starch for packaging applications. Conclusions: The isolate NA10 can be a good candidate for industrial production of PHB from cardboard industry waste water cost-effectively and ecofriendly.

Carboxymethyl cellulase (CMCase) provides a key opportunity for achieving tremendous benefits of utilizing rice straw as cellulosic biomass. Out of total 80 microbial isolates from different ecological niches one bacterial strain, identified as Bacillus sp. 313SI, was selected for CMCase production under stationary as well as shaking conditions of growth. During two-stage pretreatment, rice straw was first treated with 0.5 M KOH to remove lignin followed by treatment with 0.1 N H2SO4 for removal of hemicellulose. The maximum carboxymethyl cellulase activity of 3.08 U/mL was obtained using 1% (w/v) pretreated rice straw with 1% (v/v) inoculum, pH 8.0 at 35°C after 60 h of growth under stationary conditions, while the same was obtained as 4.15 U/mL using 0.75% (w/v) pretreated substrate with 0.4% (v/v) inoculum, pH 8.0 at 30°C, under shaking conditions of growth for 48 h. For maximum titre of CMCase carboxymethyl cellulose was optimized as the best carbon source under both cultural conditions while ammonium sulphate and ammonium nitrate were optimized as the best nitrogen sources under stationary and shaking conditions, respectively. The present study provides the useful data about the optimized conditions for CMCase production by Bacillus sp. 313SI from pretreated rice straw.

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