Moreover, the lower cell densities of S. Weltevreden detected on leaves than in/on roots were consistent with previous reports showing 30–40-fold lower levels of S. enterica on leaves in relation to roots (Cooley et al., 2003). It would be interesting to see whether

S. Weltevreden actively proliferates on the plants or whether it simply survives there without further growth. The metabolic activity of S. Weltevreden under varying conditions could be assayed using molecular tools (Artursson et al., 2005). The potential of pathogenic bacteria to exist and survive on plant surfaces is affected by adjacent physicochemical conditions and fluctuations in these environments (Brandl et al., 2004), indicating that the quantity and composition of root and leaf exudates, along with other parameters, play a major role in influencing the persistence or decline of S. Weltevreden. In conclusion, PD 332991 our results showed a great persistence of S. Weltevreden in soil, roots and Akt inhibitor on leaves, which further emphasizes the importance of strict monitoring of untreated animal manure before considering application to agricultural land. Moreover, the pathogen appeared to be mobilized from manure to spinach roots, as the number of contaminated pot cultures steadily increased throughout the evaluation period.

Consequently, introduction of enteropathogenic bacteria via manure into the food chain should be avoided and more precise safety guidelines prepared for defining actions to minimize contamination of plant produce. This work was supported by Core-organic/FORMAS. We thank the farmers who provided the samples as well as the PathoOrganic project consortium for valuable discussions. We also thank Annette Nygaard Jensen at DTU-FOOD in Denmark Ribonuclease T1 for providing us with the S. Weltevreden 2007-60-3289-1 strain. “
“Alcaligenes sp. strain PPH degrades phenanthrene via 1-hydroxy-2-naphthoic acid (1-H2NA), 1,2-dihydroxynaphthalene (1,2-DHN), salicylic acid and catechol. Enzyme activity versus growth profile

and heat stability studies suggested the presence of two distinct hydroxylases, namely 1-hydroxy-2-naphthoic acid hydroxylase and salicylate hydroxylase. 1-Hydroxy-2-naphthoic acid hydroxylase was partially purified (yield 48%, fold 81) and found to be a homodimer with a subunit molecular weight of ∼34 kDa. The enzyme was yellow in color, showed UV-visible absorption maxima at 274, 375 and 445 nm, and fluorescence emission maxima at 527 nm suggested it to be a flavoprotein. The apoenzyme prepared by the acid–ammonium sulfate (2 M) dialysis method was colorless, inactive and lost the characteristic flavin absorption spectra but regained ∼90% activity when reconstituted with FAD. Extraction of the prosthetic group and its analysis by HPLC suggests that the holoenzyme contained FAD. The enzyme was specific for 1-H2NA and failed to show activity with any other hydroxynaphthoic acid analogs or salicylic acid.