Abstract. The negative impact of chemical pesticides on the environment and the increased resistance of tomato leafminer (Tuta absoluta) field populations to chemical pesticides have promoted research on alternative control measures. Biological control with Bacillus thuringiensis (Bt) may be an alternative, especially against larval instars of T. absoluta. A total of five B. thuringiensis strains were isolated from soil sampled from two different Cow range lands in Zaria, Nigeria; and they were screened for the presence of the cry1 genes using polymerase chain reaction. Of the five isolates, two (40%) showed the presence of the cry1 genes. Results of the bioassay conducted against 2nd instar larvae of T. absoluta at 28±2°C indicated that each of the concentrations (25, 50, 75 and 100 ppm) of the spore crystal mixtures derived from the isolates harbouring cry1 genes caused significant mortality to larvae of T. absoluta after 72 hours in comparison to the control (0 ppm). Probit analysis was used to determine the LC50 and LT50 values. When the treatments were assessed at 48 and 72 hours, LC50 values against larvae were 74.1 and 25.3 ppm for isolate F3, while the LT50 values of that same isolate F3 at 100 ppm and 75 ppm were 36.3 and 42.7 hours, respectively. B. thuringiensis strain F2 achieved 68.7% reduction in T. absoluta damage on tomato plants, while B. thuringiensis isolate F3 achieved 71.3% reduction. Therefore, the spore crystal mixture derived from indigenous Bt strains is the candidate to be used for foliar application against T. absoluta and it is recommended into integrated pest control strategies for the management of T. absoluta.

This work concentrated on the isolation of lead tolerant strains of bacteria, identification of the isolated strain with the highest lead tolerance capacity using microgen identification kit. Also, the efficacy of the generated pellet (dead cell) in the bioremoval of lead from aqueous solutions was determined. A total of nine bacteria were isolated from soil collected from gold mining site in Kontagora metropolis, Niger State. Of the nine isolates, only Bacillus subtilis (KO1) possess high tolerance capacity for high levels of lead ions. The pellet generated from the Bacillus subtilis (KO1) strain was then used to adsorb lead ions from synthetic ion solutions. The isolate's removal efficiency was enhanced by optimizing several physical conditions (pH, temperature, initial lead concentration and contact time). The best optimized adsorption removal efficiency (>90%) was found at pH 3, temperature 40oC with 100 mg/L of initial concentration of lead after 3 hours of treatment. The use of the pellet generated from eco-friendly Bacillus subtilis (KO1) has great potential and additional benefits in terms of lead removal. Keywords: Bacillus subtilis; lead; adsorption; pellet; optimization

Bacillus thuringiensis (Bt) is the organism that is used most frequently in biological pest management, which is distinguished by the capacity to possess crystalline inclusions throughout the sporulation phase. There is an increasing need to use biological control in controlling plant pathogens due to the inherent advantages. However, the detection of Bt has become more time consuming and cumbersome due to the numerous available crystal genes. The goal of the study was to isolate strains of Bacillus thuringiensis from the soil, characterise the isolates using the transcriptional regulator, XRE gene and the crystal proteins cry2gene and compare the efficiency of these two biomarkers in identifying Bt species. Five different Bacillus thuringiensis strains were isolated from soil samples in Zaria, Nigeria. Polymerase chain reaction was used to detect the existence of the cry2 and XRE genes. Four (80%) of the five isolates harboured the XRE genes, while none (0%) harboured the cry2 genes. This observation is a likely indication that the XRE gene is a reliable biomarker in the identification of Bt isolates from environmental samples. In order to ensure speed and reproducibility in the detection of Bt from environmental samples, molecular techniques targeting the XREgene are recommended. Keywords: Bacillus thuringiensis; transcriptional regulator, XRE; crystal protein, cry2