Soil exo-enzyme activities across Europe-The influence of climate, land-use and soil properties

The assessment and monitoring requirements of soil quality have been debated for many years at European and Global scales. To monitor the activity and diversity of microbial communities a number of methods have been applied including the activity of extracellular soil enzymes. Here is the activity of eight hydrolytic extracellular enzymes on 79 sites across Europe measured, the sites are from five different climatic zones with three different land-uses, and they vary in physicochemical characteristics. The results show that the activity of the enzymes primarily depends on soil organic matter and to a lesser extent on pH, while the activities were not related to climate or land-use. Sites were selected to represent a broad spectrum of key soil properties across three different land-uses and five different climatic biogeographical zones across Europe, so the overall conclusion is based on the analysis of soils representing soil characteristics across Europe.</p

Detection and characterization of the novel bacteriocin entomocin 9, and safety evaluation of its producer, Bacillus thuringiensis ssp. entomocidus HD9

Aims: To identify and characterize new bacteriocins from a collection of 41 strains belonging to 27 subspecies of Bacillus thuringiensis, and to evaluate the safety of the producers. Methods and Results: Bacillus thuringiensis ssp. entomocidus HD9 produced in the culture supernatant an antimicrobial activity against Gram-positive bacteria including Listeria monocytogenes, one of four pathogenic Pseudomonas aeruginosa and several fungi. Production of the antibacterial activity, named entomocin 9, started during mid-logarithmic growth reaching its maximum at the early stationary phase. Entomocin 9 retained more than 72% of activity after incubation for 20 min at 121 C. Activity was lost after proteinase K treatment, it was stable in a pH range between 3 and 9, and resistant to lyophilization. After partial purification with ammonium sulphate precipitation followed by gel-filtration and anion-exchange chromatography, an active protein of ca 12.4 kDa was isolated. The mode of action of entomocin 9 was bactericidal and caused cell lysis of growing cells. Despite the presence of a range of virulence related genes, including haemolysin BL, nonhaemolytic enterotoxin, cytotoxin K and several hydrolytic activities, B. thuringiensis HD9 was not toxic against Vero cells. Conclusions: Entomocin 9 is a novel heat-stable, bacteriocin produced by B. thuringiensis HD9. The absence of toxicity against Vero cells suggests the suitability of strain HD9 for a safe application in antimicrobial treatments. Significance and Impact of the Study: New finding on entomocin 9 would make B. thuringiensis attractive in biotechnological applications as an antimicrobial agent in agriculture and food industry