Microbial Nutrition and Growth Microbial Nutrition Elements Major Bioelements bulk elements 98 C H N O P S Minor Bioelements Ca Na K Cl Fe Micronutrients trace elements Mn Zn Cu others metals Microbial Nutrition Molecules Organic Biomolecules Four Types proteins carbohydrates lipids nucleic acids Many are macromolecules Synthesized from smaller inorganic or small organic molecules Growth factors vitamins Organic molecules that cannot be synthesized and must be taken into the cell from the environment not all have growth factors Microbial Nutrition How do microbes acquire nutrients Transport across cell membrane Small inorganic and organic molecules salts ions simple sugars amino acids carbon dioxide oxygen water Most bacteria and fungi many protozoa Problem some molecules in the environment are macromolecules too large to get through cell wall and membrane Acquiring nutrients from large molecules Microbes secrete digestive enzymes out of the cell ex bacteria fungi protozoa How do microbes acquire nutrients cont Phagocytosis and Ingestion Some protozoa Metabolic Categories Nutritional types Based on how microorganisms obtain Carbon important molecule Energy Metabolic Categories Picture Autotrophs carbon comes from inorganic molecule CO2 Photoautotroph ex plants algea Photosynthetic bacteria ex cianobacteria most common in freshwatera Chemoautotroph ex inorganic compounds Heterotrophs carbon comes from organic compounds Chemoheterotrophs Photoheterotrophs Types of Chemoheterotrophs Predators feeds on live organisms Some protozoa few bacteria and fungi Bacteria protozoa fungi Parasites Pathogens causes damage to host organism Bacteria fungi protozoa viruses Bacterial Growth Microbiologists measure the growth of a population Types of Growth Saprobes Saprophylic Decomposers living off of dead decaying material Most fungi many bacteria some protozoa Commensals microbes that live on in another organism feeds off organic materials Open System ideal conditions and system for growth and reproduction unlimited nutrients and physical space NO build up of wastes Closed System limited nutrients and physical space build up of toxic waste products Method of reproduction Binary fission original cell divides into two new cells Growth in Open System Doubling Exponential Growth Doubling Time Generation Time time required for the population to double in size E coli and most bacteria are rapid reproducers tuberculosis bacteria is one of few that takes a long time to reproduce Growth in Closed System Standard Normal growth curve Latent Phase Exponential Growth Phase most common Secondary Phase Death Phase more cells dying than being produced Methods of Enumeration Counting Standard Viable Plate Count traditional uses petrie plate to grow bacteria count colonies Turbidity Cloudiness more bacteria high turbidity Direct Count counts total number of cells Spectrophotometer Microscopy Flow Cytometry mechanical way to count cells in a sample Standard Plate Count Picture Direct Count Microscopy Picture Factors Influencing Growth Nutrient limitation waste accumulation physical space Other physical and chemical forces Temperature Oxygen levels Hydrogen ions pH Osmotic forces salt concentration Growth Response Picture Temperature Effects on Growth Enzymes Effects rate of catalysis increasing temperature increases rate 2x per 10 C High temperatures will eventually degrade proteins stop working Membrane fluidity Decreasing temperature decreases fluidity High temperatures will melt disintegrate membrane Temperature Picture Psychorophiles cold loving 0C Mesophiles middle loving found on the human body ex pathogens 37C Thermophiles heat loving 65 70C Hyperthermophiles 95 100C Isolating Thermophiles Picture Oxygen Effect on Growth Oxygen needed for energy metabolism cellular respiration by some microbes Must be able to deal with toxic O2 derivatives ex super oxides peroxides others Have enzymes to remove toxic derivatives Superoxide dismutase Catalase and peroxidase Oxygen Effect on Growth Other microbes use alternate energy pathways that do no require oxygen fermentation and anaerobic respiration Oxygen not required or may even be toxic to microbe lack of SOD and catalase enzymes Oxygen Picture Obligate Aerobe microbes require most oxygen only grows at top Facultative Anaerobe microbes can grow with less oxygen SOD and catalase SOD and catalase Aerotolerant Anaerobe microbes can grow with less oxygen SOD lacks catalase Strict Anaerobe grows at bottom lacks SOD and catalase Atmospheric Levels higher level Anaerobe grows at lower levels Other Environmental Factors Influencing Growth Hydrogen ion concentration pH Alkaphiles best growth at HIGH pHs Acidophiles best growth in acidic conditions LOW pHs Salts best growth around 15 halophiles Pressure barophiles HIGH pressure loving Radiation damages nucleic acids of cells ex ultraviolet lights radioactive minerals rocks radiophile Growth in Aquatic Environments Planktonic free floating Biofilms attaches to surface microbial community of cells and extracellular matrix attached to a surface Implies close associations and interactions among microbes in the biofilm Biofilms Medical implications Dental disease ex gum disease Bacterial endocarditis inner lining and valves of heart Osteomyelitis bone infection Medical implants and indwelling devices ex hip and knee replacement surgery Go to Physical and Chemical Control of Microorganisms End