Exopolysaccharide production by Bacillus subtilis NCIM 2063, Pseudomonas aeruginosa NCIM 2862 and Streptococcus mutans MTCC 1943 using batch culture in different media

Three bacterial strains, Bacillus subtilis NCIM 2063, Pseudomonas aeruginosa NCIM 2862 and Streptococcus mutans MTCC 1943 were examined for their exopolysaccharide (EPS) producing ability at the laboratory level. Basal salts solution (BSS), minimal salts medium (MSM), nitrogen free medium (NFM), chemically defined medium (CDM), milk medium (MLM) and sewage from different areas were used as nutrient source individually to assess EPS production by the above mentioned bacterial strains. Nitrogen free medium favoured more EPS production (Mean: 217.13, minimum: 206.000 and Maximum: 226.000). The highest EPS production was recorded in P. aeruginosa (226 ìg ml-1) grown in nitrogen free medium followed by S. mutans and B. subtilis (220 and 206 ìg ml-1 respectively) in nitrogen free medium after 7 days of incubation at 37°C. Analysis of carbon source in sewage samples indicated the presence of reducing monosaccharides. The purified EPS was soluble only in water and was free from protein contaminants

Compatibility between Calpurnia aurea leaf extract, attraction aggregation, and attachment pheromone and entomopathogenic fungus Metarhizium anisopliae on viability, growth, and virulence of the pathogen

Metarhizium anisopliae sensu stricto (ss) (Metsch.) Sorok. isolate ICIPE 07 is being developed as biopesticide for the control of ticks. In addition, leaf extracts of Calpurnia aurea Benth, and the attraction aggregation and attachment pheromone (AAAP) are being used as ticks’ attractant. The three agents are being considered for use in combination in an autodissemination approach, whereby ticks that are attracted to semiochemicals are infected with the inoculum. Experiments were therefore conducted to evaluate in vitro the compatibility between C. aurea, AAAP, and the M. anisopliae on vegetative growth, conidial production, and spore viability. Calpurnia aurea leaf extract was compatible with the fungus at all the concentrations tested, whereas AAAP inhibited all the fungal growth parameters. The virulence of M. anisopliae formulated in emulsifiable extracts of C. aurea was also tested against different developmental stages of Rhipicephalus appendiculatus in laboratory bioassays. No significant differences in virulence were observed between M. anisopliae applied alone and M. anisopliae formulated in different concentrations of C. aurea leaf extracts. These results suggest that C. aurea leaf extracts is compatible with M. anisopliae and could be mixed together for “spot-spray” treatments as low-cost and environmental-friendly technology to control ticks in grazing field, while AAAP should be used separately.Bioscience Eastern and Central Africa Network (BecANet) and the Canadian International Development Agency (CIDA).http://link.springer.com/journal/10340hb2013mn201