摘要:

AbstractThe plant hormones, auxins and cytokinins, are involved in several stages of plant growth and development such as cell elongation, cell division, tissue differentiation, and apical dominance. The biosynthesis and the underlying mechanism of auxins and cytokinins action are subjects of intense investigation. Not only plants but also microorganisms can synthesize auxins and cytokinins. The role of phytohormone biosynthesis by microorganisms is not fully elucidated: in several cases of pathogenic fungi and bacteria these compounds are involved in pathogenesis on plants; auxin and cytokinin production may also be involved in root growth stimulation by beneficial bacteria and associative symbiosis.The genetic mechanism of auxin biosynthesis and regulation byPseudomonas, Agrobacterium, Rhizobium, Bradyrhizobium, andAzospirillum, are well studied; in these bacteria several physiological effects have been correlated to the bacterial phytohormones biosynthesis. The pathogenic bacteriaPseudomonasandAgrobacteriumproduce indole-3-acetic acid via the indole-3-acetamide pathway, for which the genes are plasmid borne. However, they do possess also the indole-3-pyruvic acid pathway, which is chromosomally encoded. In addition, they have genes that can conjugate free auxins or hydrolyze conjugated forms of auxins and cytokinins. InAgrobacteriumthere are also several genes, located near the auxin and cytokinin biosynthetic genes, that are involved in the regulation of auxins and cytokinins sensibility of the transformed plant tissue. Symbiotic bacteriaRhizobiumandBradyrhizobiumsynthesize indole-3-acetic acid via indole-3-pyruvic acid; also, the genetic determinants for the indole-3-acetamide pathway have been detected, but their activity has not been demonstrated. In the plant growth-promoting bacteriumAzospirillum, as inAgrobacteriumandPseudomonas, both the indole-3-pyruvic acid and the indole-3-acetamide pathways are present, although inAzospirillumthe indole-3-pyruvic acid pathway is of major significance. In addition, biochemical evidence for a tryptophan-independent indole-3-acetic acid pathway inAzospirillumhas been presented.

ISSN:1040-841X    

DOI:10.3109/10408419509113531

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractRifamycins are primarily produced by Gram-positive bacteriumAmycolatopsis mediterranei, which belongs to the order Actinomycetales. These antibiotics, apart from their application against pathogens of tuberculosis and leprosy, have also been found to be effective against several other pathogens includingMycobacterium aviumandPneumococcus. Because of the importance of rifamycin, the producer strainA. mediterraneihas been genetically manipulated since 1957 in order to develop a strain that can either produce larger amounts of rifamycin or derivatives of rifamycin. In this article, the importance of the producer strain, traditional methods (mutations and recombination) of strain improvement, their limitations, and the development of a cloning vector and transformation methods that have made recombinant DNA techniques accessible for genetic manipulations ofA. mediterraneiare discussed.

ISSN:1040-841X    

DOI:10.3109/10408419509113532

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractMicrobiology of meats has been a subject of great concern in food science and public health in recent years. Although many articles have been devoted to the microbiology of beef, pork, and poultry meats, much less has been written about microbiology of lamb meat and even less on restructured lamb meat. This article presents data on microbiology and shelf-life of fresh lamb meat; restructured meat products, restructured lamb meat products, bacteriology of restructured meat products, and important foodborne pathogens such asSalmonella, Escherichia coli0157:H7, andListeria monocytogenesin meats and lamb meats. Also, the potential use of sodium and potassium lactates to control foodborne pathogens in meats and restructured lamb meat is reviewed.

ISSN:1040-841X    

DOI:10.3109/10408419509113533

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor

摘要:

AbstractSalmonellais one of the most important foodborne pathogens around the world. The knowledge that very low numbers ofSalmonellacells can be infectious emphasizes the need for stringent food safety measures. Traditional methods for isolating and identifyingSalmonellain foods rely on preenrichment, selective enrichment in selective and differential media, biochemical tests, and serological confirmation. Recent advances in diagnostic technology have considerably altered testing methods for foodborneSalmonella. Many commercial assay systems and kits that use newer technologies are available to facilitate the identification ofSalmonellain foods. These systems include miniaturized biochemical tests, new media formulations, automated instrumentation, DNA/RNA probes, antibody-dependent assays, and polymerase chain reaction. The technologies used for these systems are described, and the various kit formats are compared. Among the limitations of detection methods in terms of food safety are timeliness, limits of detection, and differentiation of virulent and nonvirulent isolates. Current efforts of prevention measures and strategies at different links of the food chain such as consumer education and hazard analysis and critical control point (HACCP) programs are reviewed. Global approaches to food safety are needed.

ISSN:1040-841X    

DOI:10.3109/10408419509113534

出版商:Taylor&Francis    

年代:1995

数据来源: Taylor