This study reports the biodiversity of thermophilic cellulolytic bacterial strains that present in the north Malaysian mangrove ecosystem. Soil samples were collected at the four most northern state of Malaysia (Perak, Pulau Pinang, Kedah and Perlis). The samples obtained were first enriched in nutrient broth at 45°C and 55°C prior culturing in the carboxymethylcellulose (CMC) agar medium. Repeated streaking was performed on the CMC agar to obtain a pure culture of each isolate prior subjecting it to hydrolysis capacity testing. The isolates that showing the cellulolytic zone (halozone) were sent for 16S rRNA sequencing. Total seven isolates (two from Perak, three from Kedah, another two were from Perlis and Penang each) showed halozone. The isolate (KFX-40) from Kedah exhibited highest halozone of 3.42 ± 0.58, meanwhile, the one obtained from Perak (AFZ-0) showed the lowest hydrolysis capacity (2.61 ± 0.10). Based on 16S rRNA sequencing results, 5 isolates (AFY-40, AFZ-0, KFX-40, RFY-20, and PFX-40) were determined to be Anoxybacillus sp . The other two isolates were identified as Bacillus subtilis (KFY-40) and Paenibacillus dendritiformis (KFX-0). Based on growth curve, doubling time of Anoxybacillus sp . UniMAP-KB06 was calculated to be 32.3 min. Optimal cellulose hydrolysis temperature and pH of this strain were determined to be 55°C and 6.0 respectively. Addition of Mg 2+ and Ca 2+ were found to enhance the cellulase activity while Fe 3+ acted as an enzyme inhibitor.

No abstract

BACKGROUND: A good colloidal stability of magnetite nanoparticles (MNPs) dispersion is of utmost importance for its environmentally related applications. In the present work, a water-soluble anionic polyelectrolyte, poly(sodium 4-styrene sulfonate) (PSS), was used to stabilize dispersions of MNPs in a pH-dependent aqueous medium. RESULTS: An excellent methylene blue (MB) dye removal efficiency at equilibrium of up to 94% has been observed by the colloidally stabilized nano-magnetites. Dynamic light scattering and electrophoretic analysis showed that the PSS-coated MNPs exhibited better colloidal stability, with an almost constant hydrodynamic diameter of ∼150 nm and insignificant clustering behavior throughout the measuring time scale of 5 h. Transmission electron microscopy evidenced the success coating of PSS onto MNPs. In terms of its chemical resistance, the PSS-coated MNPs were able to tolerate a wide pH range from 2 to 10. This work depicts a simple physiochemical coating method to stabilize dispersions of nano-magnetites, which promoted a better MB adsorption capacity of PSScoated MNPs at 14.9 mg g-1 than the naked MNPs at 10.38 mg g-1. The adsorption process follows Langmuir isotherm and pseudo-second-order reaction kinetics with both correlations R 2 > 0.99. PSS-coated MNPs demonstrated outstanding regeneration capacity for four batch adsorption cycles with an almost consistent MB removal efficiency higher than 85%. CONCLUSION: This in-house developed nano-sorbent has potential in economical applications with a less budgeted adsorbent replacement (at least 4 cycles of regeneration) for low-cost separation of pollutants, such as MB from polluted water.

No abstract