Aquatic Bacteria Fungi v Objective w To know

Aquatic Bacteria & Fungi v Objective w To know the main cellular features, physiology and function of bacteria & fungi in water and wastewater environments w To know the species interactions in anaerobic digestion w to understand how substrate conditions and nutritional requirements determine the competitive success of these microbes in pollutant degradation processes. v References w Gray N. F. Biology of Wastewater Treatment w Lester J. N. & Birkett J. W. Microbiology and Chemistry for Environmental Scientists & Engineers w Madigan M. T. , Martinko J. M. , Parker J. Brock - Biology of Microorganisms w Stanier R. Y. General Microbiology w Kiely G Environmental Engineering v Lecture Outline w Bacteria - Cell Structure Physiology & Function w Fungi- Cell Structure Physiology & Function

Bacteria v What are they? w Prokaryotic organisms w Bacteria (eubacteria), Archaea (archaebacteria) v Importance in Environmental Engineering w Biodegradation w Nutrient Cycling w Pathogens in Contaminated Waters

Bacterial Cell Structure v Size w smallest living organisms, 1 m. v Shape w typically cocci or rods (bacilli), spiral, stalked, filamentous. w multicellular swarms (gliding myxobacteria, myxococcus) v DNA w circular, supercoiled, no nuclear membrane. w Extranuclear DNA or Plasmids. v Reproduction w Asexual = Binary fission, Conjugation via Pili.

Cell Structure v Cell Wall w Two types, Gram Positive, Gram Negative w Both have Peptidoglycan w Gram Negatives also have Lipopolysaccharide (LPS) v Archaea w similar to G+ve, have pseudopeptidoglycan

Cell Structure v Flagellum w w May be present - Motile Polar or peritricious Driven by Proton motive Force (PMF) Chemotaxis - tumble frequency increases. v Cytoplasm w complex subcellular organelles usually absent. w vesicular and lamellar structures (mesosomes) form by invagination of cytoplasmic membrane (e. g. N-fixing, Nitrifying, and Phototrophic bacteria). w cytoplasmic membrane essential (maintains PMF). w Ribosomes - Protein synthesis w Enzymes - metabolism w Granules (Inclusions) w Gas Vesicles (buoyancy, e. g. cyanobacteria)

Characteristics v Oxygen Requirements w w Aerobic Microaerophilic Facultative (aerobe) Anaerobic (strict) v Growth Requirements - Organic substrates w Heterotrophic (Chemoorganotrophs) – Pseudomonas, Bacillus, Zoogloea, etc. w Key role in Nutrient Cycling w Biodegradation of Organic Detritus w Soluble low molecular weight substrates e. g. acetate, methanol, sugars. w Polymers degraded by extracellular hydrolytic Enzymes.

Metabolism v Growth Requirements - Inorganic substrates w Autotrophic (Chemolithotrophic, Phototrophic) – Nitrosomonas, Nitrobacter, Methanococcus, Chlorobium, etc. w w Reduced forms of sulphur H 2 S, S 0, S 2 O 32 -, SO 3 Reduced forms of nitrogen NH 3 Hydrogen H 2 Iron Fe 2+ v Growth Requirements - Light w w Photosynthetic (phototrophic) light and CO 2 oxygenic blue-green (cyanobacteria) anoxygenic green-sulphur (Chlorobium sp. )

Bacteria in Aquatic Environments v Natural Waters w Energy source (depends on metabolism and dissolved species) v Cellular Nutrient Requirements w w C, H, O, N, P, S. vitamins, growth factors, trace elements. Dissolved Gases (O 2, CO 2, H 2 S) Nitrogen is usually limiting in oligotrophic waters. v Origin of Nutrients w w Algal secretions, death. Zooplankton feeding, death. Soil run-off discharge of treated (& untreated) effluents.

Bacteria in Aquatic Environments v Planktonic w suspended free cells w vertical movement – O 2 – stratified nutrients (in anoxic zone) v Particulate w associated with POM v Biofilms w surfaces of stones and plants (epiphytic) w can be slow growing, psychrophilic environments.

Methanogenesis v Methanogenic Bacteria (Archaea) w Chemolithotrophic (autotrophs) w H 2 and CO 2 w e. g. Methanobacterium, Methanococcus, Methanospirillum w 4 H 2 + H+ + HCO 3 CH 4 + 3 H 2 O w Energy -136 k. J (but as low concentrations = -30 k. J) w Low p. E (anaerobic) environments w Inhibited in Marine sediments w Other substrates include Acetate, Methanol, Formate etc.

METHANOGENESIS Complex polymers Protein, Cellulose Hydrolysis Monomers Sugars, amino acids Fermentation H 2 + CO 2 Acetogenesis Acetate Propionate Butyrate Alcohols Acetate Syntrophs Fermentation H 2 + CO 2 Methanogens Acetoclastic METHANE Acetate Methanogens H 2 -Utilising, Acetoclastic

Methanogenesis v Methanogenesis involves Co-operation w Inter-species Hydrogen transfer w Several Steps from a complex substrate (Cellulose) 1. Hydrolysis (depolymerisation) to cellobiose (G-G) 2. Fermentation of Glucose to Fatty acids, H 2 and CO 2 3. Fatty acids oxidised to H 2 and CO 2 (SYNTROPHS) 4. Methanogens produce CH 4 w Syntrophs require H 2 to be consumed w Typically H 2 < 10 -4 M

Fungal Cells v Size w Typically 5 m diameter filament, variable length v Structure w Filamentous – hyphae bundled as Mycelia (moulds) Usually branched w Rods (Yeasts ) w Chitin and cellulose cell walls v DNA w chromosomes, nuclear membrane. v Reproduction w Asexual = tip cell, sexual = spores called conidia.

Physiology of Fungi v No chlorophyll, produce extra-cellular enzymes. v Heterotrophic nutrition. Parasitic or Saprophytic v Very slow rate of growth cf. bacteria. Tolerate low DO, low p. H, High C: Nratios. Dairy & Trade wastes Environmental Requirements 1. Nutrients - Only organic C - or Organic C + N } and some need vitamins C 10 H 17 O 6 N i. e. low ratio N: C therefore tolerate N deficiency. 2. Moisture relatively low concentration H 2 O (75 -80%) (Usually 95 -98% in bacteria etc. ) Therefore can grow on moist and aquatic environments.

Physiology of Fungi 3. p. H Normally prefer low p. H (produce acid themselves) 4. Oxygen Normally prefer O 2 (i. e. aerobic) although some species can tolerate anaerobic conditions temporarily. Aerobic respiration: C 6 H 12 O 6 6 CO 2 + 6 H 2 O Anaerobic respiration fermentation: C 6 H 12 O 6 2 C 2 H 5 OH + 2 CO 2 (Yeasts) 5. Temperature Grow in range 2 - 25 o. C, optimum = 15 o. C i. e. psychrophilic - cold-loving

Importance of Fungi in Freshwater 1. Fungi play similar role to bacteria. Very important in breakdown of complex organics to simpler substances for algae (i. e. NH 3 mineralization) White rot fungi (Phenaerochete) degrade lignin and produce enzymes that degrade complex pollutant molecules Associated with polluted waters because of high nutrient requirements. 2. Indicators of pollution Fusarium, Leptomitis and Geotrichum associated with a mesosaprobic zone in Saprobian system.

Importance of Fungi in Freshwater 3. Actinomycetes and Fungi Give Taste and Odour problems in treated water. a) Grow on reservoir walls, and release complex organic compounds when dead. (TASTE AND ODOUR). Also grow on dead algae. Very common after algal blooms. Saprophytic b) Grow in cold water systems in buildings, especially where cold and hot water pipes are adjacent. 4. Sewage Fungus growths in rivers receiving certain industrial wastes (e. g. wood pulping and dairy wastes). 5. Marine Waters

Sewage Fungus WRC Survey of 90 Sewage Fungus Associations thick, slimy growths on river bed pulp mill, dairy or strong sewage Leptomitis lacteus Geotrichum Fusarium aqueductum Other fungi 4% 7% 3% 10% Sphaerotilus natans Zoogloea 89% 94% Stigeoclonium Diatoms Ulothrix 10% 18% Sewage Fungus - FUNGI BACTERIA* 4% therefore a misnomer ALGAE Mainly bacteria

Fungi in Activated Sludge Rare, unless high proportion of trade wastes (e. g. Canneries, Dairies, Distilleries) High C: N ratio Low p. H Low DO Overloading Under aeration Give rise to BULKING SLUDGE. *Geotrichum Pullularia pullulans Sporotrichum Also filamentous bacteria give rise to same problem e. g. Nocardia, Sphaerotilus natans, Thiothrix, Microthrix + many others

Fungi in Trickling Filters Leptomitis lacteus Fusarium aqueductum Geotrichum candidum Sepedonium spp. Subbaromyces speldens Ascoidea rubescens often present in feed channels. Colonise surface of filter Able to withstand impact of sewage. Common in sub-surface zone. Phoma, Saprolegnia, Leptomitis lacteus occasionally present. In winter, species with low optimum temperature e. g. Sepedonium dominate.

Fungi in Trickling Filters Industrial Wastes e. g. from Canneries, Dairies, Distilleries etc. encourage growth of fungi (High C: N ratio) Problems caused by Fungi: Heavy growth causes PONDING, especially in winter. Operational procedures: Film accumulation controlled by w Recirculation, w Alternating double filtration w low frequency dosing.

Colonisation of Trickling Filters Fungi, high energy of maintenance (40 -50 mg/l BOD) Bacteria have much lower saturation constants than fungi (Ks = 0 -20 mg/l BOD for sewage bacteria) Therefore bacteria continue to grow at low substrate concentrations i. e. Bacteria have a competitive advantage over fungi at low substrate concentrations. Vice versa at high substrate concs.