BioSigma Bioleaching Seeds (BBS): A New Technology for Managing Bioleaching Microorganisms

In Bioleaching, although it is already prove that chalcopyrite can be dissolved by microorganisms, a major task is to do it efficiently in economical terms at industrial scale. BioSigma Bioleaching Seeds (BBS) represents a biotechnological breakthrough for the production of bioleaching solutions on demand with high concentrations of biomining microorganisms. This innovation is mainly a product based on the encapsulation of BioSigma bioleaching microorganisms in a natural matrix of alginate. This technology gives the following operational advantages: 1. High concentration of inoculum. 2. Long period of inoculum storage (more than 1 year). 3. Reduction of volume and costs of transport of bioleaching solutions. 4. Homogeneous mineral inoculation; uniform inoculation of the ore using solid capsules. 5. Protection against toxic elements to retain the viability and activity of the bioleaching solutions. 6. Addition of additives for incorporation of nutrients or other molecules that enhance the activity. 7. Encapsulation of different bioleaching microorganisms producing specific "bioleaching seeds" for each biohydrometallurgical process. All the above advantages make this new technology a very attractive alternative to enhance bioleaching processes at on site operations and overcome stressful conditions for biomining microorganisms.

Effects of inoculum potential on screening for resistance to Plasmodiophora brassicae in greenhouse trials

Several factors, including growth medium, inoculum density, and inoculum storage affected the reaction of resistant and susceptible Brassicas to <i>Plasmodiophora brassicae</i> in the greenhouse. A high level of disease was achieved using Peat-litte mix R and a commercial greenhouse mix. There was litte difference in disease incidence when spore suspensions were pipeted into planting holes or when seedlings were dipped into spore suspensions. Seedlings transplanted from sand or Petri dishes gave higher levels of disease than direct seeding. Two-year frozen storage of clubs reduced the inoculum potential to a level unable to define resistance. Inoculum levels of 10^3-7 spores per ml from fresh clubs, or 10^5-7 spores per ml from clubs frozen for 2 or 4 years, produced 90% club incidence of susceptible cauliflower and Chinese cabbage, A concentration of only 10^6-8 spores per ml from fresh clubs was required for maximum disease expression in a cauliflower line partially resistant to clubroot.