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Cellulosic biomass is considered one of the most promising sources for the production of alternative renewable bioenergy and other valuable products. Identification and optimization of strains with high enzymatic activity that can overcome constraints imposed by the cellulosic structure is an essential step in the development of new biotechnologies. The aim of this study was to isolate and identify thermophilic (50 °C) and mesophilic (37 °C) cellulolytic bacteria from soil and leaves samples at Kerman, Iran. Degrader bacteria were isolated using serial dilution and pour plate method. Media contained carboxymethylcellulose (CMC), and filter paper was used as sources of carbon. Totally 22 mesophilic and 17 thermophilic bacterial strains which produced clear zones were further identified by morphological and biochemical tests. Screening of purified bacteria was performed to identify cellulase-producing bacteria by Congo red test. These bacteria were compared to each other based on cellulase activity, the percentage of growth, and extracellular protein amounts. The strains with the highest enzymatic activity were determined by the DNS method. The isolated US5 and US7 grew rapidly, and produced cellulase. The US5 created the largest clear zones (7 mm). Besides, these strains were selected for analysis of 16S rRNA sequence. The results showed that selected bacteria strains belong to Brevibacillus borstelensis. The B. borstelensis strains isolated in this study showed a suitable cellulase enzyme activity., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Increasing environmental pollutants such as heavy metals have become one of the most severe health dangers because of rapid industrialization. Exposure to lead and nickel heavy toxic metals can lead to hazardous diseases affecting most of the organs in humans. Bioremediation is a process that uses the ability of microorganisms or plants to detoxify environmental contaminants at lower costs than physicochemical techniques. This study isolated halophilic bacteria from Khara salt lake in Iran and screened their ability to resist lead and nickel. After screening stages, three selected strains including Bacillus sp. A21, Oceanobacillus sp. A22 and Salinicoccus A43 were identified by16S rDNA sequencing and the related sequences were submitted to GeneBank with accession IDs MN588312, MN588313, and MN 588,314, respectively. These strains resist 7.2 mM, 4.1 mM, and 6.7 mM lead and 3.6 mM, 3.7 mM, and 4.1 mM nickel, respectively. Investigation of growth pattern and evaluation of bioremediation ability by atomic absorption spectroscopy revealed that Bacillus sp. A21 could decrease lead and nickel in culture medium up to 97.5% and 76%, respectively. Oceanobacillus sp. A22 showed higher lead bioremediation rate (98.8%) and lower nickel-bioremediation rate (73.5%). Salinicoccus sp. A43 showed the least bioremediation ability (92% lead and 71.7% nickel). The ability of selected strains to synthesize lead and nickel nanoparticles was evaluated using UV/Vis spectrophotometry and Energy-Dispersive X-ray Spectroscopy (EDX). Particle dimensions were measured using Scanning Electron Microscopy (SEM). Bacillus sp. A21 and Oceanobacillus sp. A22 strains were able to synthesize lead nanoparticles; however, Salinicoccus sp. A43 could synthesize both lead and nickel nanoparticles., (© 2021. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)