Tunicamycin-resistant mutants of Bacillus amyloliquefaciens are deficient in amylase, protease and penicillinase synthesis and have altered sensitivity to antibiotics and autolysis

Mutants of Bacillus amyloliquefaciens resistant to at least 10 micrograms/ml of tunicamycin were isolated and shown to be pleiotropic. The mutants were more resistant to streptomycin, chloramphenicol, kanamycin and neomycin than was the parent strain but less resistant to penicillin G and tetracycline. They were more autolytic, presumably due to an altered cell wall. The mutants produced reduced levels of amylase, penicillinase and both metal and serine protease besides having an enhanced sporulation frequency and being more motile.     

Control of the growth of Alicyclobacillus acidoterrestris in industrialized orange juice using rosemary essential oil and nisin

The use of rosemary essential oil (RO) and its combination with nisin (RO+N) in preventing the multiplication of Alicyclobacillus acidoterrestris in orange juice was evaluated. The minimum inhibitory and bactericidal concentrations (MIC and MBC) for RO were both 125 μg ml⁻¹ while RO+N displayed a synergistic effect. The use of RO and RO+N at concentrations of 1, 4 and 8× MIC in orange juice for 96 h was evaluated in terms of their sporicidal effectiveness. With regard to the action against A. acidoterrestris spores, RO at 8× MIC was sporostatic, whereas RO+N at 1× MIC was sporicidal. Morphological changes in the structure of the micro-organism after treatment were also observed by microscopy. Furthermore, flow cytometric analysis showed that most cells were damaged or killed after treatment. In general, the antioxidant activity after addition of RO+N decreased with time. The results demonstrate that using the combination of RO and nisin can prevent the A. acidoterrestris growth in orange juice.     

The change of behaviour of two strains of Leishmania after cultivation in a defined medium

Attempts have been made to characterize two strains of Leishmania that became infective to golden hamsters only after they had been maintained for several years in a chemically defined culture medium. Observations were made on the growth rates of promastigotes in vitro, course of infection in hamsters, morphology of amastigotes, and electrophoretic mobility patterns of eight isoenzymes. Information was obtained about the buoyant densities of n-DNA and k-DNA, and one strain was tested against monoclonal antibodies. The identity of both strains remains obscure.     

Control of Chagas disease in Brazil

Chagas disease (South American trypanosomiasis) is a chronic but often fatal disease endemic throughout much of Latin America. Serological surveys suggest around 24 million people seropositive for the causative agent, Trypanosoma cruzi (Fig. 1), with over 65 million living in the endemic areas and at risk to infection. In Brazil, over 25 million people are considered at risk, and control of the disease constitutes one of Brazil's public health priorities. Treatment or vaccination against T. cruzi is impossible at the public health level because suitable drugs or vaccines are not available. But it is well recognized that transmission can be interrupted by eliminating the domestic vectors - blood-sucking reduviid bugs of the subfamily Triatominae. In Brazil, eradication of Triatoma infestans - the major domestic vector of T. cruzi - is now seen as a feasible target by the Ministry of Health. However, although other domestic vectors can also be controlled, they will retain their sylvatic ecotopes from which they can reinvade houses. In this article, Joao Carlos Pinto Dias explains the current Brazilian policy, high-lighting the successful elimination of T. infestans from much of the southern part of the country.     

A note on the use of cross-linked starch in microbiology with special reference to detecting amylase production

Anilogel-E, a cross-linked starch, can be used with distinct advantages where native starch or soluble starch are conventionally used, e.g. in scoring for amylolytic organisms, as an ingredient of fermentation media, and in enhancing protoplast regeneration. It is particularly useful for the direct visualization of amylase producing micro-organisms on solid media, making prior replication of colonies unnecessary.     

Sphaerotilus Growing in a Continuous-Flow Apparatus: Calcium Nutrition of1

Sphaerotilus natans required calcium for the production of sheaths and probably requires calcium for growth as well, though at a lower concentration. Neither strontium nor barium substituted for calcium. S. natans grew attached to the culture vessels of the continuous-flow apparatus even when no sheaths were produced. Tentative evidence showed that the requirement for calcium is shared by the manganese-oxidizing species S. discophorus.     

Growth-promoting Activity of Spent Sulfite Liquor for Sphaerotilus natans Growing in a Continuous-Flow Apparatus

The calcium in ammonia-base spent sulfite liquor, unlike that in calcium-base spent liquor, is not available for growth of Sphaerotilus natans. It has not been possible to obtain a mixed slime with Sphaerotilus as the dominant organism in a continuous-flow apparatus fed spent sulfite liquor.