Aims:  To isolate and characterize a potent molybdenum‐reducing bacterium. Methods and Results:  A minimal salt medium supplemented with 10 mmol l−1 molybdate, glucose (1·0%, w/v) as a carbon source and ammonium sulfate (0·3%, w/v) as a nitrogen source was used in the screening process. A molybdenum‐reducing bacterium was isolated and tentatively identified as Pseudomonas sp. strain DRY2 based on carbon utilization profiles using Biolog GN plates and partial 16S rDNA molecular phylogeny. Strain DRY2 produced 2·4, 3·2 and 6·2 times more molybdenum blue compared to Serratia marcescens strain DRY6, Enterobacter cloacae strain 48 and Eschericia coli K12, respectively. Molybdate reduction was optimum at 5 mmol l−1 phosphate. The optimum molybdate concentration that supported molybdate reduction at 5 mmol l−1 phosphate was between 15 and 25 mmol l−1. Molybdate reduction was optimum at 40°C and at pH 6·0. Phosphate concentrations higher than 5 mmol l−1 strongly inhibited molybdate reduction. Inhibitors of electron transport system such as antimycin A, rotenone, sodium azide and cyanide did not inhibit the molybdenum‐reducing enzyme activity. Chromium, copper, mercury and lead inhibited the molybdenum‐reducing activity. Conclusions:  A novel molybdenum‐reducing bacterium with high molybdenum reduction capacity has been isolated. Significance and Impact of the Study:  Molybdenum is an emerging global pollutant that is very toxic to ruminants. The characteristics of this bacterium suggest that it would be useful in the bioremediation of molybdenum pollutant.

Clavibacter michiganensis subsp. michiganensis (Cmm) is a quarantine organism in Europe and in many other countries. It is one of the most severe bacterial pathogens affecting tomato. Screening tomato plants for their resistance level to Cmm requires a large amount of space under quarantine conditions and is therefore costly. This project developed a new inoculation protocol on in vitro tomato plants to facilitate a more economic and higher throughput disease screening. A new method using the PathoScreen system was tested to localize green fluorescent protein-tagged Cmm in planta and to quantify the pathogen based on the percentage of corrected GFP (cGFP%). The system was sensitive in detecting the GFP-tagged Cmm in the shoots, but in the roots a high autofluorescence masked detection and thus sensitivity of the assay. The in vitro protocol was tested on several wild relatives of tomato, which were previously screened in a greenhouse assay. The correlation between wilt symptoms in vitro and wilt symptoms in the greenhouse was overall moderate (r = 0.6462). The protocol worked well in differentiating the two parents that were used in the mapping studies. This study shows that the in vitro protocol can be efficiently used for resistance breeding in many tomato genotypes.

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