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Inorganic Nutrient Availability & Phytoplankton Growth: the start of Biogeochemical Cycles Re-read pp. 56-67, Habitat Determinants of Primary Production Re-read pp. 31-34 and pp.39-52, Ecology of the Water Column Read assignments on environmental microbiology originally listed for week of Feb. 11th inorganic 1 1. Inorganic Nutrient Uptake & Nutrient-dependent growth 2. Autotrophic Growth (formation of new organic C, N, P, S, Si etc. from external inorganic sources) / Plant Biomass /Animal Biomass /Bacterial Biomass What are the forms of inorganic Carbon that Phytos use for growth metabolism? CO 2, HCO 3 - for PS, CO 3 = for Coccolithophorid shells but not CO or CH 4 (used by some special types of bacteria) What are the forms of inorganic Nitrogen that Phytos use for growth metabolism? NH 3 (NH 4 +), NO 3, NO 2 by all kinds of phytos N 2 only by cyanobacteria (heterocycsts) What are the forms of inorganic Phosphorous that Phytos use for growth metabolism? PO 4 What are the forms of inorganic Sulfur that Phytos use for growth metabolism? SO4 but not S, H 2 S (used by some special types of bacteria) What are the forms of inorganic Silicon that Diatoms only use for growth metabolism? Si(OH) 4 These are the macronutrients that when in short supply, can limit phytoplankton growth

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Inorganic carbon (CO 2 and HCO 3 ) autotrophy ultimate source of metabolic organic carbonsunlight source of metabolic energy phototrophy DOM excretion DOM Can determine growth rates by following changes in Biomass (POC, Chl) or Cell Numbers over time = photoautrophy Respiration ATPNADP+, used to calculate the rate of POC accumulation & derive a doubling time (Dt) as an index of growth rate Net Primary Production, used to calculate the rate of POC accumulation & derive a doubling time (Dt) as an index of growth rate Uptake of Inorganic nutrients, trace metals, vitamins Combine via Intermediary metabolism to synthesize and turn over complex molecules for Cell structure & function. e.g. RNA, DNA, amino acids, enzymes, Lipids, cofactors, cell structural components,, etc.

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Most bacteria, many protists & all phytos except diatoms grow by first enlarging in size & then divide roughly in half by binary fission (e.g. mitosis). Daughter cells are the same size. The smallest sized cells in the population tend to be cells just recently divided and/or prior to any enlargement by growth. Size variation for a single specie means growth. bacteria dinoflagellate Paramecium Cell division by Binary Fission

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Due to rigid Silicon cell wall, diatoms divide within existing cell and synthesize new cell walls separating into 2 daughter cells. This is also binary fission, but the average cell size with each new generation; also explains the large range of sizes in diatom populations. Cell division by Binary Fission 1=>2=>4=>8=>16.... etc. Logarithmic Growth or Exponential Growth : N = N o 2 n NN o where N = Number at any time, N o = Number at time zero, 2n times 2 to the nth power where "n" = number of generations. n =1 NoNoNoNo n =2 n =3 Growth rate linked to the time between doublings of a generation = g t gtgt generationn4321

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Plot of increases in cell number vs time for cell dividing by binary fission = Growth Curve Logarithmic Growth N = No2 n N = No2 n Exponential Growth N = No2 n N = No2 n n = number of generations (doublings) required for a population at an initial cell density (No) to reach a specific higher cell density (N) n = (log Nt-logNo )/log2 log2 = 0.301 When cell concentrations of 10 2 reaches 10 5 cells/Liter in 4 hrs, how many generations has passed? n =1 n =2 10 5 10 2 0.301= (5-2)/0.301 = 9.67 generations (doublings) n = (log 10 5 -log 10 2 ) / 0.301= (5-2)/0.301 = 9.67 generations (doublings) What was the generation time (gt) or doubling time (Dt)? = Dt = 4 hours/ 9.67 generations (doublings)/ = 0.41 hrs ~ 25 minutes gt = Dt = 4 hours/ 9.67 generations (doublings)/ = 0.41 hrs ~ 25 minutes

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Laboratory studies with uni-algal populations are used to determine exponential growth rates In batch cultures, cell properties such as size, internal nutrient composition, and metabolic function vary considerably during the various growth phases. Batch Culture: algal cells are allowed to grow and reproduce in a closed container. They have a finite amount of nutrient, and when that is exhausted, their growth stops and eventually they die. For best & reproducible results, a defined growth medium is used instead of natural waters. Known quantities of plant nutrients are added. Also, growth temperature and light conditions are known and held constant. Microscopic cell counts are made daily.

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Phytoplankton Growth Curve lag phase- after inoculation, cells are becoming acclimated to the new environment (temp, nutrients, etc.) No growth in presence of growth nutrients. The longer the lag phase, the greater the metabolic adaptation needed before cell division can resume. Helps identify ‘growth history’ of a inoculum. stationary phase ell growth slows & then ceases as nutrients are exhausted &/or waste products build up in the media. Indicates Maximum Yield as cells enter period Nutrient limitation and no growth. The length of time in this phase indicates ability of algae to sustain on existing nutrient reserves following exponential growth. Important to looking at survival strategies for many in situ conditions where nutrients limit growth. stationary phase- cell growth slows & then ceases as nutrients are exhausted &/or waste products build up in the media. Indicates Maximum Yield as cells enter period Nutrient limitation and no growth. The length of time in this phase indicates ability of algae to sustain on existing nutrient reserves following exponential growth. Important to looking at survival strategies for many in situ conditions where nutrients limit growth. Decay or death phase- number of viable (living cells) in the stationary phase culture decreases (usually due to toxicity of waste products). Fewer cells will revive if nutrients added. log phase cells have adapted & are dividing at a constant rate (i.e. the maximum for the species under the given conditions of temp, pH, nutrients, oxygen, etc.). Provides information to determine exponential doubling times (Dt) and specific growth rates ( ). log phase - cells have adapted & are dividing at a constant rate (i.e. the maximum for the species under the given conditions of temp, pH, nutrients, oxygen, etc.). Provides information to determine exponential doubling times (Dt) and specific growth rates ( ). Further metabolic distinctions between early, mid & late exponential growth.

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Competition study Can you tell a story that might Explain these results? Conditioning the medium for optimal growth Cell density Examples of Growth Curves for Phytoplankton Determined from Batch Culture Experiments Phosphate depletion during growth PO 4 in media Cells/ml Something about conditioning he medium by 1st sp. suppresses growth of the 2nd sp.

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