Abstract: Free living nitrogen fixing bacteria are those that lives freely on rhizosphere of a young growing plant or those living in a close association with root of plants (Rhizobacteria) but not symbiotically. In most tropical soil, Nitrogen and other essential nutrients element are the most limiting nutrients which deficiencies could lead to slow growth and reduced crop production. Free living nitrogen fixing bacteria has the potential of secreting nitrogenase enzymes and produces organic acids such as glycolic, acetic, malic, succunic acids which fix atmospheric nitrogen directly into the soil for plants growth and development. To this end, the study on isolation, identification and screening of Azotobacter chroococcum from soil of Keffi, Nasarawa State, Nigeria was carried out from May to September 2018. Soil samples were collected from eight different locations and Azotobacter strains were isolated and identified using standard microbiological methods. The 16SrRNA gene sequence analysis of the strain showed maximum similarity of 96% with Azotobacter chroococcum of the reference type strain deposited in RDP Gen Bank database. Azotobacter strains isolated from four different locations showed coloured zone ranging between 16-10mm. Similarly, Percentage amount of nitrogen released by each Azotobacter strain in the culture broth ranging between 1.19% - 5.11% in an increasing order.Abstract: Free living nitrogen fixing bacteria are those that lives freely on rhizosphere of a young growing plant or those living in a close association with root of plants (Rhizobacteria) but not symbiotically. In most tropical soil, Nitrogen and other essential nutrients element are the most limiting nutrients which deficiencies could lead to slow growth ...Show More
Abstract: This study evaluates cellulose degrading bacteria isolates from paper mill dumpsites and their cellulolytic activity. Forty-one cellulose-degrading bacteria (CDB) were isolated from soil samples from seven different paper and pulp mill dump sites using enrichment method. The isolates were identified based on Morphology and Biochemical characterization while the identities of the potent cellulolytic bacteria isolates were confirmed by 16SrRNA sequencing. The optimum pH, temperature and incubation period for cellulose production by the CBD were determined. Isolates EFB3, ADB4, EFB1 and EFB4 exhibited the maximum zone of clearance around the colony with diameter of 50mm, 43mm, 44mm and 54mm and with the hydrolytic value of 10, 10.6, 8.8 and 7.6 respectively. The three selected bacteria with highest cellulose-degrading ability had 96% similarity with Enterobacter soli, Eubacterium ventriosum and Klebsiella michiganensis. Production of cellulase by the bacteria were influenced by environmental factors. Klebsiella michiganensis had optimum activity (38.5U/ml/min) after 72 hours while Enterobacter soli and Eubacterium ventriosum had optimum cellulase activity of 35.5U/ml/min and 32.2U/ml/min respectively after 48 hours. Enterobacter soli, Klebsiella michiganensis and Eubacterium ventriosum had optimum cellulase activity of 38U/ml/min, 35.6U/ml/min and 35.2U/ml/min respectively at pH7 while they recorded lower cellulase activity at acidic and alkaline pH ranges. Eubacterium ventriosum and Klebsiella michiganensis exhibited optimum activity of 25.12 U/ml/min and 20.55 U/ml/min respectively at 40°C. Enterobacter soli had the least cellulase activity with its optimum (15.02U/ml/min) at 35°C. The findings of this study revealed the abundance of bacteria equipped with the essential enzymatic capability to decompose cellulosic materials in the study area. These bacteria can also be used for mass production of cellulase.Abstract: This study evaluates cellulose degrading bacteria isolates from paper mill dumpsites and their cellulolytic activity. Forty-one cellulose-degrading bacteria (CDB) were isolated from soil samples from seven different paper and pulp mill dump sites using enrichment method. The isolates were identified based on Morphology and Biochemical characterizat...Show More
