Publications by authors named "Wojciech J Janisiewicz"

A growing number of bacteria and fungi have been found to promote plant growth through mutualistic interactions involving elements such as volatile organic compounds (VOCs). Here, we report the identification of an environmentally isolated strain of (herein named TC09), that substantially enhances plant growth after exposure beyond what has previously been reported. When cultured on Murashige and Skoog (MS) medium under conditions, tobacco seedlings () exposed to TC09 cultures for 20 days increased stem height and whole plant biomass up to 25- and 15-fold, respectively, over controls without exposure.

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Penicillium spp. cause blue mold of stored pome fruit. These fungi reduce fruit quality and produce mycotoxins that are regulated for processed fruit products.

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Strawberries are available throughout the year either from production in the field or from high and low tunnel culture. Diversity of production conditions results in new challenges in controlling diseases before and after harvest. Fungicides have traditionally been used to control these diseases; however, their limitations necessitate a search for new approaches.

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Bacterial and yeast antagonists isolated from fruit surfaces have been effective in controlling various post-harvest diseases, and several microbial antagonists have been developed into commercial products. Our knowledge of the fruit microbial community, with the exception of grapes, apples and some citrus fruit, is rudimentary and the potential of the resident yeasts for biocontrol remains largely unknown. We determined the occurrence of yeasts on plum surfaces during fruit development from the pre-hardening stage until harvest for 2 years.

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Enophytic fungi were isolated from plum (Prunus domestica) leaves, identified with ITS1 and ITS4 primers, and their antagonistic activity was tested against Monilinia fructicola, which causes brown rot, blossom blight, and twig blight of stone fruits, and Colletotrichum gloeosporioides, which causes anthracnose on a variety of fruit crops. The production of antifungal compounds was determined in agar-diffusion and volatile inverted-plate tests. A total of 163 fungi were recovered from 30 plum trees, representing 22 cultivars.

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A polygalacturonase (PG) isozyme was isolated from Penicillium solitum-decayed Anjou pear fruit and purified to homogeneity with a multistep process. Both gel filtration and cation exchange chromatography revealed a single PG activity peak, and analysis of the purified protein showed a single band with a molecular mass of 43 kDa, which is of fungal origin. The purified enzyme was active from pH 3.

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Microflora of fruit surfaces have been the best source of antagonists against fungi causing postharvest decay of fruit. However, there is little information on microflora colonizing surfaces of fruits other than grape, apple, and citrus. We characterized bacterial microflora on nectarine fruit surfaces from the early stage of development until harvest.

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A polygalacturonase (PG) was extracted and purified from decayed tissue of 'Anjou' pear fruit inoculated with Penicillium expansum. Ammonium sulfate precipitation, gel filtration, and cation exchange chromatography were used to purify the enzyme. Both chromatographic methods revealed a single peak corresponding to PG activity.

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The fresh-cut produce industry has been the fastest-growing portion of the food retail market during the past 10 years, providing consumers with convenient and nutritious food. However, fresh-cut fruits and vegetables raise food safety concerns, because exposed tissue may be colonized more easily by pathogenic bacteria than intact produce. This is due to the higher availability of nutrients on cut surfaces and the greater potential for contamination because of the increased amount of handling.

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Transformation efficiencies as high as 10(7) transformants microg(-1) DNA have been previously reported for pseudomonads using electroporation protocols established for E. coli with plasmid DNAs prepared from methylation proficient E. coli hosts.

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Losses from postharvest fruit diseases range from 1 to 20 percent in the United States, depending on the commodity. The application of fungicides to fruits after harvest to reduce decay has been increasingly curtailed by the development of pathogen resistance to many key fungicides, the lack of replacement fungicides, negative public perception regarding the safety of pesticides and consequent restrictions on fungicide use. Biological control of postharvest diseases (BCPD) has emerged as an effective alternative.

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The food-borne human pathogen Listeria monocytogenes survived and its populations increased on cv. Delicious apple slices at 10 or 20°C in air or controlled atmosphere of 0.5% O and 15% CO, but did not grow at 5°C.

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