Trichoderma viride obtained from maize cob was investigated for chitinase production. Effects of temperature, pH and some metal ions on the chitinase produced were determined. The enzyme was then purified by ammonium sulphate precipitation, DEAE-cellulose ion-exchange chromatography and sephadex G-100 gel filtration. There was progressive increase in the chitinolytic activity of T. viride from zero hour to the 50th hour. The optimum temperature and pH for chitinolytic activity of T. viride was 50 o C and 5 respectively. There was reduction in the relative activity of chitinase produced by T. viride when EDTA and MnCl 2 were used as metal ions.Trichoderma viride was most sensitive to EDTA followed by MnCl 2 . The activity was maximum when CaCl 2 was used. The chitinase produced by T. viride was stable at temperatures of 40 and 50 o C.The chitinase produced was also stable at pH 6 and 7. Keywordschitinolytic activitymetal ionsstable -T. viride,

Okra (Abelmoschus esculentum) is an annual vegetable that is cultivated in the tropics and subtropics. Infestation by Sclerotium rolfsii can cause serious economic losses to farmers. Therefore, the curative effect of Trichoderma viride and mancozeb on S. rolfsii on okra plants was monitored in the green house in both non-sterile and sterile soils. Okra cultivated in non-sterile soils were healthier and stronger than those in sterile soils although plants were taller in sterile soil. Generally, the fresh weight of okra leaf, root and stem were higher in non-sterile soil than in sterile soil. The fruit yields of okra in non-sterile soil were higher than those of the sterile soil, irrespective of the treatments. Based on the results of this investigation, it is not recommended to use sterile soil if one is interested in yield of the plant.

Rhizobium species are involved in symbiotic relationship which can be exploited in agriculture to enhance crop and pasture growth without the addition of nitrogen fertilizers. However, a number of environmental factors are known to affect the symbiotic efficiency of Rhizobium. This current study evaluated tolerance of Rhizobium species isolated from root nodules of cowpea obtained from Akure, Nigeria to variation in temperature, pH levels, salt concentrations, heavy metals as well as antibiotics. Three Rhizobium species were isolated from root nodules of Vignaunguiculata and Phaseolus vulgaris after 34 days of planting yeast extract mannitol agar (YEMA). Their tolerance to environmental factors such as temperature, pH, sodium chloride, heavy metals as well as antibiotics was determined. All the isolates grew very well at 28oC, moderately at 37oC but their growth was hampered at 50o C. Maximal growth was observed at neutral pH. However, Sinorhizobium sp showed high tolerance to pH 7.0. Also, the isolates showed high tolerance to low concentration of sodium chloride (0.1%) and heavy metals with reduction in their optical density at higher concentrations. Rhizobium sp showed high level of tolerance at 4% compared to Mesorhizobium sp. and Sinorhizobium sp. Rhizobium spp. showed resistance to all the antibiotics investigated while Mesorhizobium sp. was sensitive to only to pefloxacin and sparfloxacin, while Sinorhizobium sp. was only sensitive to pefloxacin. The isolates in this study can be assessed for their suitability as inoculants forcowpea in soils below temperature 50oC and at neutral pH. J. bio-sci. 26: 15-24, 2018

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This study reveals the chitinase producing ability of some fungi isolates cultured from the rhizosphere of different fruit trees such as mango, cassava, guava, and banana inside FUTA farm. A total of 16 isolates identified as Aspergillus nidulans, A. niger, A.flavus, A. fumigatus, A. ripens, Trichoderma viride, Mucor mucedo, Penicillium frequentans, Rhizopus stolonifer, Paecilomyces fumosoroseus, Gibbelula suffulfa and Geotrichum albidum were obtained and screened for chitinolytic activity. The effect of cultural conditions such as pH, temperature, metal ion, nitrogen source and carbon source was determined on Aspergillus nidulans, being the best chitinase producer. Further, the chitinase produced by Aspergillus nidulans was concentrated by ammonium sulphate precipitation and purified consecutively by gel filtration and ion-exchange chromatography. The optimum pH and temperature for chitinase activity and stability were examined as well as the effect of metal ions on the enzyme activity. The enzyme was most active at pH 7.0 and it was relatively stable at pH 4.0 - 9.0 retaining over 60% of initial activity after 120 min of incubation. The enzyme was most active at 50°C, possessing high thermal stability at high temperature of 70°C. The purified chitinase was significantly inactivated at 80°C and almost completely at 90°C when it was pre-incubated at these temperatures for 60 min. The enzyme was strongly inhibited by FeSO4, ZnCl2 and MnCl2 and was less sensitive to CaCl2 and KCl. This purified Aspergillus nidulans chitinase can be used as a catalyst for the degradation of chitin-containing compounds.