High G + C Gram-Positive Bacteria: The Acintobacteria Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Chapter 22 High G + C Gram-Positive Bacteria: The Acintobacteria

Copyright © The McGraw-Hill companies, Inc Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. High G + C Bacteria volume 4 of Bergey’s Manual of Systematic Bacteriology, 2nd Edition Actinomycetes gram-positive, aerobic bacteria that produce filamentous cells called hyphae and differentiate into asexual spores adapt to climates similar to fungi

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General Properties of the Actinomycetes Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. General Properties of the Actinomycetes source of most currently used antibiotics also produce metabolites that are anticancer, antihelminthic, and immunosuppressive complex life cycle most are not motile motility is restricted to flagellated spores

Life Cycle of Actinomycetes Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Life Cycle of Actinomycetes involves development of filamentous cells (hyphae) and spores hyphae can form branching network can grow on surface of substrate or into it to produce a substrate mycelium some hyphae differentiate to form an aerial mycelium which extends above substratum at this stage forms secondary metabolites, some of which are medically useful

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Life Cycle of Actinomycetes… Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Life Cycle of Actinomycetes… aerial mycelium form exospores which are called sporangiospores if they are located in a sporangium produced in response to nutrient deprivation withstand desiccation but not heat resistant spores dispersed by wind for new bacteria

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Ecological Significance of Actinomycetes Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Ecological Significance of Actinomycetes widely distributed in soil play important role in mineralization of organic matter most are free living, but a few are pathogens

Characteristics Used in Actinomycete Taxonomy Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Characteristics Used in Actinomycete Taxonomy four major cell wall types based on peptidoglycan structure and sugar content other than N-acetylglucosamine and N-acetylmuramic acid

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Copyright © The McGraw-Hill companies, Inc Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Table 22.1

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Phylum Actinobacteria Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Phylum Actinobacteria 16S rRNA evidence shows 1 class (Actinobacteria), five subclasses, six orders, 14 suborders, 44 families consists of actinomycetes and their high G + C gram-positive relatives

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Suborder Actinomycineae Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Suborder Actinomycineae one family with five genera irregularly shaped, gram-positive rods swelling, club shapes, or other deviations from normal rod morphology aerobic or facultative metabolism

Copyright © The McGraw-Hill companies, Inc Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Actinomyces straight or slightly curved rods and slender filaments with true branching may have swollen, clubbed, or clavate ends facultative or obligate aerobes (require CO2) peptidoglycan contains lysine and not diaminopimelic acid or glycine normal inhabits of oral mucosa cause of lumpy jaw in cattle ocular infection, actinomycoses, and peridontal disease in humans

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Suborder Micrococcineae Genus Micrococcus Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Suborder Micrococcineae Genus Micrococcus aerobic, catalase-positive rods that occur in pairs, tetrads, or irregular clusters usually nonmotile often pigmented yellow, orange, or red widespread in soil, water, and on human skin does not undergo morphological differentiation

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Genus Arthrobacter aerobic, catalase-positive rods, respiratory Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Arthrobacter aerobic, catalase-positive rods, respiratory lysine in peptidoglycan rod-coccus growth cycle exponential phase irregular, branched rods reproduce by snapping division early stationary phase begin to change to coccoid form when transferred to fresh medium, coccoid cells produce outgrowths of actively growing rods

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Genus Dermatophilus Dermatophilus (type IIIB) Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Dermatophilus Dermatophilus (type IIIB) form packets of motile spores with tufts of flagella facultative anaerobes parasites of mammals cause streptothrichosis – skin infection

Suborder Corynebacterineae Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Suborder Corynebacterineae has seven families with many known genera such as Corynebacterium Mycobacterium Nocardia

Genus Corynebacterium Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Corynebacterium aerobic and facultative, catalase positive straight to curved rods with tapered ends and club shaped after snapping division bacteria often remain partially attached resulting in palisade arrangements of cells

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Genus Corynebacterium Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Corynebacterium form metachromatic granules cell walls have meso-diaminopimelic acid some are harmless soil and water saprophytes many are animal and human pathogens e.g., C. diphtheriae - diphtheria

Genus Mycobacterium in family Mycobacteriaceae Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Mycobacterium in family Mycobacteriaceae straight or slightly curved rods that sometimes branch or form filaments aerobic and catalase positive filaments readily fragment into rods and coccoid bodies very slow growing on culture media

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Mycobacterial Cell Walls Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Mycobacterial Cell Walls contain waxes with 60 to 90 carbon mycolic acids cell wall surface consists of the glycolipid trehalose dimycolate once called cord factor cell wall very hydrophobic impenetrable by antibiotics acid-fast basic fuchsin dye cannot be removed from cell by acid alcohol treatment

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Important Species of Mycobacterium Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Important Species of Mycobacterium M. bovis tuberculosis in cattle, humans M. tuberculosis tuberculosis in humans M. avium complex (MAC) various diseases M. leprae leprosy

Copyright © The McGraw-Hill companies, Inc Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Nocardia along with genus Rhodococcus make up the family Nocardiaceae develop a substrate mycelium that readily breaks into rods and coccoid elements some also form an aerial mycelium and conidia

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Impact of Nocardia most are free-living saprophytes Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Impact of Nocardia most are free-living saprophytes can degrade many molecules e.g., petroleum hydrocarbons, detergents, benzene involved in biodegradation of rubber joints in water and sewage pipes some are opportunistic pathogens causing nocardiosis usually infect lungs; can infect central nervous system

Genus Rhodococcus widely distributed in soils and aquatic habitats Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Rhodococcus widely distributed in soils and aquatic habitats degrade an enormous variety of molecules such as petroleum hydrocarbons, detergents, benzene, polychlorinated biphenyls (PCBs), various pesticides may reduce sulfur from fuels and reduce air pollution from sulfur oxide emissions

Suborder Micromonosporineae Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Suborder Micromonosporineae only one family, Micromonosporaceae extensive substrate mycelia lack or have rudimentary aerial mycelia sporangiospores motile or nonmotile found in soil and aquatic habitats (especially freshwater) soil dwellers play important roles in plant and animal decomposition some produce antibiotics

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Genus Propionibacterium Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Propionibacterium found on skin and in digestive tract of animals also in dairy products such as cheese used in production of Swiss cheese e.g., P. acne – involved in development of body odor and acne vulgaris

Suborder Streptomycineae Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Suborder Streptomycineae one family, three genera aerial hyphae that divide in single plane to form chains of 3–50 nonmotile spores all have type I cell wall G+C DNA content is 69–78% filaments grow by tip extension

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Genus Streptomyces are 1 to 20% of culturable soil microbiota Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Streptomyces are 1 to 20% of culturable soil microbiota produce geosmin volatile substance that is source of moist earth odor important in mineralization process aerobically degrade many resistant substances (e.g., pectin, lignin, and chitin) produce vast array of antibiotics, other bioactive compounds, and antibiotic resistance genes most are nonpathogenic saprophytes

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Streptomyces coelicolor Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Streptomyces coelicolor one of the largest bacterial genomes, 8.67 Mbp largest number of genes (7,825) 65 RNA polymerase sigma subunits 80 two-component regulatory systems genes for 18 additional secondary metabolites

Pathogenic Streptomycetes Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Pathogenic Streptomycetes Streptomyces scabies scab disease in potatoes and beets Streptomyces somaliensis actinomycetoma infection of subcutaneous tissues in humans leads to swelling, abscesses, and bone destruction

Suborder Streptosporangineae Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Suborder Streptosporangineae three families, 16 genera aerial mycelia bear pairs or short chains of spores whole cell homogenates contain sugar madurose Actinomadura associated with the disease acinomycetoma

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Suborder Frankineae genera Frankia and Geodermatophilus Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Suborder Frankineae genera Frankia and Geodermatophilus both form multilocular sporangia characterized by clusters of spores both have type III cell walls Geodermatophilus type IIIC, motile spores, aerobic Frankia – type IIID, nonmotile spores, microaerophile, fixes nitrogen, symbiotic with nonleguminous plants

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Genus Sporichthya Sporichthya lack substrate mycelium Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Genus Sporichthya Sporichthya lack substrate mycelium use holdfasts to anchor to substratum grow upward to form aerial mycelia release motile, flagellated conidia in presence of water

Order Bifidobacteriales Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. Order Bifidobacteriales one family and ten genera e.g., genera Falcivibrio and Gardnerella found in human genitourinary tract Gardnerella thought to be major cause of vaginitis e.g., Bifidobacterium nonsporing rods found in mouth and intestinal tract of warm-blooded animals, in sewage, and in insects

e.g., Bifidobacterium bifidus Copyright © The McGraw-Hill companies, Inc. Permission required for reproduction or display. e.g., Bifidobacterium bifidus pioneer colonizer of human intestinal tract does not appear to be major cause of disease probiotic agent

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