Four treatments applied on potato seed tubers i.e. talc only, chitosan only, Streptomyces melanosporofaciens strain EF-76 in talc and S. melanosporofaciens strain EF-76 in chitosan were compared for their efficiency to reduce common scab incidence. As previously reported the joint application of the geldanamycin-producing S. melanosporofaciens strain EF-76 and chitosan was effective to control common scab of potato. Nevertheless, field application of S. melanosporofaciens EF-76 did not allow the selection of geldanamycin-resistant actinomycetes (GRA) in the bulk soil during the potato growing season. The number of GRA on harvested potato tubers was, however, significantly higher in treatments that contained chitosan than in other treatments suggesting that chitosan might promote the establishment of the antagonistic actinomycete on progeny tubers. Biolog EcoPlates were used to determine the metabolic profiles of the bacterial soil communities. A permutation MANOVA analysis detected significant differences within the metabolic profiles of the bacterial communities at the potato flowering period but not at the beginning of the season or a week before harvest. A combination of S. melanosporofaciens EF-76 and chitosan thus represents a promising tool against common scab, with low short-term impact on soil bacterial communities.

Spores of Streptomyces melanosporofaciens EF-76, an actinomycete that inhibits the growth of several plant pathogens, were incorporated in beads of chitosan and polyphosphate using the entrapment technique called complex coacervation. The degradation of spore-loaded beads was monitored by measuring the residual amount of chitosan in soil and by enumerating the S. melanosporofaciens population over time. After the introduction of spore-loaded chitosan beads into soil, the amount of chitosan in sterile soil remained at 1.550 mg/g throughout the first week and diminished to 0.101 mg/g after 7 weeks. Bead degradation proceeded faster in non-sterile soil but a progressive release of both chitosan oligomers and the antagonistic microbial agent was nevertheless observed. Application of these spore-loaded chitosan beads to seed potato tubers protected progeny tubers against common scab.

Spores of the biocontrol agent, Streptomyces melanosporofaciens EF-76, were entrapped by complex coacervation in beads composed of a macromolecular complex (MC) of chitosan and polyphosphate. A proportion of spores entrapped in beads survived the entrapment procedure as shown by treating spores from chitosan beads with a dye allowing the differentiation of live and dead cells. The spore-loaded chitosan beads could be digested by a chitosanase, suggesting that, once introduced in soil, the beads would be degraded to release the biocontrol agent. Spore-loaded beads were examined by optical and scanning electron microscopy because the release of the biological agent depends on the spore distribution in the chitosan beads. The microscopic examination revealed that the beads had a porous surface and contained a network of inner microfibrils. Spores were entrapped in both the chitosan microfibrils and the bead lacuna.

Around the world, hazardous wastes and contaminated soils have become a major environmental concern. Over the last five years, the traditional treatment of contaminated soils by incineration has been challenged by thermal separation techniques, which frequently involved a rotary kiln or a conveyor kiln. In these thermal pyrolytic processes, the contaminants may be removed by vaporization at high temperature a n d or by a continuous stream of hot inert gas. An extensive review of North American demonstration and commercial cleanup methods for hazardous waste sites can be found in the literamre (U.S. EPA, Centre SaintLaurent, 1993). A few examples of thermal pyrolytic processes for the treatment of contaminated soils are given below.Rotary kilns were initially used for incineration, but have since been used in less destructive thermal techniques. Some of the North American processes operating with a rotary kiln since 1992 are described here. The anaerobic thermal processor (U.S. EPA, 1992; Air and Waste Management Association, 1993) treats soils at 600" C in a 25 tonshrunit. In the X ' W process (US. EPA, 1992), the contaminants are volatilized by a continuous N, stream at 500" C in a 7 tonshr unit. The low temperature thermal aeration process ( U S . EPA, 1992 Reintjes, 1985) and the Siemens process (Bege and Meininger, 1989) both use two kilns. In the Ecotechniek BV, the combustion of the gases produced in the first reactor is used to heat the second reactor. In addition, a part of the hot soil exiting the second reactor is reintroduced into the frrst reactor to heat the soils entering the system. In the second kiln used in the Siemens process, organic compounds are oxidized by a stream of hot gas consisting of N,, CO, and 0,. In the NBM process (De Leur, 1988), the amount of oxygen in the kiln's atmosphere is controlled. The reactor walls are heated to a temperature that will cause spontaneous combustion of the pyrolytic products to consume the oxygen that is present. One of the main advantages of the rotary kiln is its ability to treat a large variety of wastes, both solid and liquid. Conveyor kilns using screws and paddles are used to treat sludges and relatively solid material. A limitation of some of these reactors is the need to attain rather high temperatures for efficient treatment. The use of a carrier gas is also inconvenient, as it necessitates a subsequent treatment or separation of the particles and contaminants contained in the carrier gas.Thus, it would be advantageous to design a reactor that combines the strong points of both systems-i.e, treats a large variety of wastes, permits a rather precise control of temperature and pressure, does not require a high operating temperature or a carrier gas, and is more energy-efficient.In this article, we would like to describe a reactor with a new configuration, specially developed for the treatment of soils contaminated with organic material. However, the kiln's inside configuration cannot be revealed at this point, as a patent describing the reactor ha...