Biocontrol activity

Vassilev, N., Vassileva, M., and Nikolaeva, I. (2006). Simultaneous P-solubilizing and biocontrol activity of microorganisms Potentials and future trends. Appl. Microbiol. Biotech-nol. 71, 137-144. 

The production of HCN by Pseudomonas species has also been implicated in biological control. Hydrogen cyanide is a general biocide that chelates divalent cations and interferes with respiration by interaction with cytochrome c oxidase. Fluorescent pseudomonads are insensitive to cyanide especially as growth ceases and many strains with biocontrol activity can produce it in the presence of a suitable precursor such as glycine and Fe3+. A number of recent reviews have covered the topic of biological control by Pseudomonas in significant details [13-17]. 

An oxidoreductase is highly expressed in a virulence - loss - mutant of the cabbage yellows fungus having biocontrol activity (A. Okabe, Tokyo Univ. of Agric. Tech., Japan)... 

The fungus Laetiseria arvalis (Basidiomycota, Aphyllophorales, Corti-ciaceae) was isolated from soil and shown to have biocontrol activity against the soil pathogens Rhizoctonia solani and Pythium ultimum [38]. The antimicrobial... 

For decades, fungi have been a valuable and preferred source of enzymes and secondary metabolites because of their ease of isolation, readily manipulative cultivation conditions, greater biomass production, and downstream processing. Fungal chitinases, in particular, strains of Trichoderma have been studied extensively to identify, isolate, clone and express a number of genes responsible for a variety of chitinases production especially in the development of transgenic plant varieties. Other than the biocontrol activities... 

Haran, S., Scitlckler, H., Chet, I. Molecular mechanisms of lytic enzymes involved in the biocontrol activity of Trichoderma harzianum. Microbiology 1996,142, 2321-2331. 

The causes of the beneficial effects resulting from the dietary supplementation of probiotics are diverse. In the passage that follows, each of the biocontrol activities that have been associated with probiotics are briefly mentioned. For examples from both research and practice and more detailed information, some excellent reviews have been written (Gatesoupe, 1999, 2010 Kesarcodi-Watson et al., 2008 Qi et al., 2009 Verschuere, 2000 Vine et al., 2006). 

There has been considerable interest in the use of plants for bioremediation and this merits a rather extensive discussion. Plants can play an important role in bioremediation for several reasons (1) they can transport contaminants from the soil, (2) they can metabolize the contaminants after uptake, or (3) they can produce exudes that support microbial activity for degradation of the contaminants. In addition, bacteria can produce metabolites that counter the effect of toxins produced by fungi, and serve as biocontrol agents that diminish the need for the application of agrochemicals. Plant exudates play an important role in supporting the growth and activity of bacteria that carry out the degradation of contaminants in the rhizosphere and rhizoplane (the external surface of roots... 

Siddiqui lA, D Haas, S Heb (2005) Extracellular protease of Pseudomonas fluorescens CHAO, a biocontrol factor with activity against the root-knot nematode Meloidogyne incognita. Appl Environ Microbiol 71 5646-5649. 

The yeasts also have been evaluated for antifungal activity. Spadaro and others (2008) reported that Hanseniaspora uvarum, Rhodotorula spp., and Metschnikowia pulcherrima reduced the development of P. expansum on apples. In this work the biocontrol effectiveness was assessed on four apple cultivars, Golden Delicious, Stark Delicious, Granny Smith, and Royal Gala. The efficacy was higher on the cv. Golden Delicious. 

An antibiotic inhibition zone often appears around Trichoderma spp. interacting with other fungi. The genus contains many species which produce secondary metabolites. Claydon et al. (23) have identified an antibiotic from T. harzianum as a volatile, 6-n-pentyl-2H-pyran-2-one this was recently shown to be an active antibiotic from T. koningii (24). The volatile appeared to be the factor responsible for the coconut smell of some biocontrol-effective strains of T. harzianum (25). However, in a Petri-plate assay, it can be difficult to be certain that antibiosis is involved. As well as competitive growth, lytic enzymes could also contribute to the action and Trichoderma has been shown to produce / -l,3-glucanase and chitinase (26-29). 

Ligon JM, Hill DS, Flammer PE, Torkewitz NR, Hofmann D, Kempf H-J, van Pee K-H (2000) Natural Products with Antifungal Activity from Pseudomonas Biocontrol Bacteria. Pest Manag Sci 56 688... 

Chemin, L., Chet I. Microbial enzymes in biocontrol of plant pathogens and pests. In, Enzymes in the Environment Activity, Ecology, and Applications. Burns, R.G, Dick, R.P., eds. Marcel Dekker New York, 2002 pp. 171-225. 

Kamensky, M., Ovadis, M., Chet, I., and Chemin, L. Soil-borne strain IC14 of Serratiaplymuthica with multiple mechanisms of antifungal activity provides biocontrol of Botrytis cinerea and Sclerotinia sclerotiorum diseases. Soil BiolBiochem 2003 35 323-331. 

Ligon, J.M., Hill, D.S., Hammer, P.E., Torkewitz, N.R., Hofmann, D., Kempf, H.J., van Pee, K.H. Natural products with antifungal activity from Pseudomonas biocontrol bacteria. Pest Manage Sci 2000 56 688-695. 

Green, H. Heiberg, N., Lejbolle, K., Jensen, D.F. The use of a GUS transformant of Trichoderma harzianum, strain T3a, to study metabolic activity in the spermosphere and rhizosphere related to biocontrol of Pythium damping-off and root rot. Eur J Plant Pathol 2001 107 349-359. 

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