Rhizosphere soil enzymes as indicators of perturbations caused by enzyme substrate addition and inoculation of a genetically modified strain of Pseudomonas fluorescens on wheat seed

Abstract

Original article can be found at: http://www.sciencedirect.com/science/journal/00380717 Copyright Elsevier Ltd. DOI : 10.1016/S0038-0717(97)00061-8Comparative assays for determining chitobiosidase, N-acetyl glucosaminidase, acid phosphatase, alkaline phosphatase, phosphodiesterase, aryl 2 sulfatase and urease activities from small samples of soil were developed. The enzyme assays and ATP biomass assessments were used to monitor perturbations caused by the presence of Pseudomonas fluorescens in the rhizosphere of wheat. Microbial biomass as well as the measured enzyme activities decreased with depth, except for acid phosphatase activity which was similar at all depths. A combined substrate mix addition of urea, colloidal chitin and glycerophosphate significantly increased N-acetyl glucosaminidase, chitobiosidase, aryl sulfatase and urease activities but did not cause a significant difference in acid and alkaline phosphatase and phosphodiesterase activities. Inoculation of seeds with P. fluorescens resulted in significant increases in rhizosphere chitobiosidase and urease activities at 5-20 cm depth and a significant decrease in alkaline phosphatase activity. Inoculation with the bacterium in the presence of substrate mix gave opposing effects to those treatments without substrate mix addition: chitobiosidase, aryl sulfatase and urease activities were significantly lower and alkaline phosphatase was significantly higher at the 5-20cm depth interval with inoculation of bacteria. Biomass values for the combined bacteria and substrate mix treatment were significantly higher than the substrate mix alone treatment

Effect of immobilized phosphate solubilizing bacteria on wheat growth and phosphate uptake

“…For the assay, 2 mL of 0.5 M sodium acetate buffer adjusted to pH 6.5 and 11 (Naseby and Lynch, 1997) and 0.5 mL of substrate were added to 0.5 mL of PVK medium incubated at 37 °C for 90 min. The reaction was stopped by cooling at 2 °C for 15 min.…”

Interactions between arbuscular mycorrhizal fungi and phosphate-solubilizing fungus (Mortierella sp.) and their effects on Kostelelzkya virginica growth and enzyme activities of rhizosphere and bulk soils at different salinities

“…Soil enzyme activities are sufficiently sensitive to perturbations caused by microbial inoculation (Naseby and Lynch 1997), and these measurements can give insights on mineralization of important nutrient elements, such as carbon, nitrogen, and phosphorus (Ceccanti et al 1994). The measurement of enzyme activities and the integration of the measured activities in a single index can provide information on microbial activity in soil (Nannipieri et al 2002(Nannipieri et al , 2003.…”

“…Microorganisms are activated in the rhizosphere soil (Cordier et al 2000). Therefore, it is important to determine enzyme activities of both rhizosphere and bulk soils, which can affect the concentrations of available P and other nutrients in soil (Naseby and Lynch 1997;Ceccanti et al 1994). However, there is no information regarding the use of such parameters for monitoring the ecological impact of AMF and PSF inoculation in saline soil.…”

Soil enzyme activities in the rhizosphere of field-grown sugar beet inoculated with the biocontrol agent Pseudomonas fluorescens F113

“…In contrast, inoculation with a Flavobacterium species resulted in increased activity of -galactosidase, -galactosidase, -glucosidase and -glucosidase in the rhizosphere of wheat (Mawdsley and Burns 1994). Naseby and Lynch (1997b) found perturbations in several soil enzyme activities following the introduction of P.…”

“…The same enzyme activities were perturbed by P. fluorescens inocula in short term small microcosm studies Lynch 1997c and1998) and long term large microcosm studies (Naseby and Lynch 1997b). The protective effect of the strain is mediated by the production of 2,4-diacetylphloroglucinol (DAPG; Fenton et al 1992;Shanahan et al 1992), an antimicrobial compound that inhibits various soil microorganisms (reviewed by Keel 4 et al 1992;Shanahan et al 1992).…”