[Isolation, identification and enzyme characterization of a thermophilic cellulolytic anaerobic bacterium].

The research paper presents the identification and enzymatic characterization of a thermophilic cellulolytic anaerobe, a bacterium capable of breaking down cellulose at high temperatures, which was isolated from horse manure. The study concludes that the identified bacterium, Strain HCp, has high potential for cellulolytic ethanol production.

Isolation and Identification of the Bacterium

• The studied bacterium, referred to as strain HCp, was isolated from horse manure using the Hungate anaerobic technique.
• The bacterium’s phylogeny was determined through 16S rDNA sequencing, a common method used in microbial identification for determining evolutionary relationships.
• Physiologically, strain HCp was found to be a strictly anaerobic Gram-negative bacterium, able to form spores, exhibit movement, and display resistance to the antibiotic neomycin.
• The strain was found to be most similar to Acetivibrio cellulolyticus and A. cellulosolvens, with a 97.5% sequence similarity.

Enzyme Characterization

• Various substrate utilization tests were conducted to determine the bacterium’s ability to degrade and utilize different types of plant and food residues, including filter paper cellulose, cellulose powder, microcrystalline cellulose, cotton wool, rice straw and gelatin.
• It was found that HCp was able to metabolise a large variety of saccharides, such as cellobiose, glucose, xylose, xylan, raffinose, maltose, sorbose, fructose and galactose.
• These enzymatic abilities point towards the potential utilisation of this strain in recycling and biofuel production through the breakdown of plant and food waste.

Growth Conditions and Cellulose Degradation

• The growth pH for HCp ranged from 6.5 to 8.5, the ideal temperature spanned from 35 to 70 degrees Celsius and the optimal NaCl concentration ranged from 0% to 1.0% with the optima being pH 6.85, 60 degrees Celsius, and 0.2% NaCl.
• Under these optimal growth conditions, strain HCp was able to degrade up to 90.4% of filter paper cellulose after 10 days.
• The enzymes produced by this bacterium, including FPA, CMCase, beta-glucosidase, and xylanase, all demonstrated high thermal stability with optimal temperatures of 70 degrees Celsius for all except xylanase, which had an optimal temperature of 60 degrees Celsius.

Conclusion

• Based on the findings, the paper concludes that strain HCp has considerable potential for the production of cellulolytic ethanol, which could serve as a new source of renewable biofuel.
• The ability of this bacterium to utilize a wide range of substrates and produce highly thermostable enzymes makes it a potentially valuable resource in the industrial scale biofuel production process.