Chapter 5Chapter 5

The Microbial WorldThe Microbial World

VirusesViruses

• Non-cellular infectious agents that Non-cellular infectious agents that have two basic characteristics:have two basic characteristics:– Not capable of reproduction without a Not capable of reproduction without a

host cellhost cell– Structure: Structure:

• Nucleic acid core- can be ____ or ____Nucleic acid core- can be ____ or ____• Capsid (Protein coat)- consists of numerous protein Capsid (Protein coat)- consists of numerous protein

subunits organized into rod-like or many sided shape. subunits organized into rod-like or many sided shape. Protein coat also contains specific proteins that bind Protein coat also contains specific proteins that bind with receptors on host cells. Many glycoprotein with receptors on host cells. Many glycoprotein spikes extend from coat-these spikes mutate so spikes extend from coat-these spikes mutate so frequently that our immune system cannot keep up.frequently that our immune system cannot keep up.

VirusesViruses• Notable Types of Viruses:Notable Types of Viruses:

• Retroviruses- store genetic information in Retroviruses- store genetic information in the form of nucleic acid known as RNAthe form of nucleic acid known as RNA

• Bacteriophages – viruses that infect Bacteriophages – viruses that infect bacteriabacteria

• Bacteriophages are either lytic or lysogenicBacteriophages are either lytic or lysogenic

• Viruses in eukaryotes can similarly be Viruses in eukaryotes can similarly be active or latentactive or latent

VirusesViruses

• Viruses in the Marine Community:Viruses in the Marine Community:– They are common in marine watersThey are common in marine waters– They can infect bacteria, plankton, fish, They can infect bacteria, plankton, fish,

sea turtles and marine mammalssea turtles and marine mammals– Lysis (bursting) of viral infected cells Lysis (bursting) of viral infected cells

spills contents and releases large spills contents and releases large amounts of organic matter that can be amounts of organic matter that can be utilized by other organisms (dissolved utilized by other organisms (dissolved organic matter or DOM)organic matter or DOM)

ProkaryotesProkaryotes

• Archea and BacteriaArchea and Bacteria

• Characteristics of Archean and Bacterial Characteristics of Archean and Bacterial Cells:Cells:– ____- no nucleus____- no nucleus– Single chromosome (normally circular)- some Single chromosome (normally circular)- some

also with plasmidsalso with plasmids– Most with cell wallMost with cell wall– Great metabolic diversityGreat metabolic diversity– microscopicmicroscopic

ProkaryotesProkaryotes

• Archea – Archea – – Ancient organisms – fossils found that date Ancient organisms – fossils found that date

back 3.8 billion yearsback 3.8 billion years– Some live in very extreme environmentsSome live in very extreme environments– Variety of metabolic typesVariety of metabolic types– Widely distributed in the marine communityWidely distributed in the marine community– They can tolerate wide ranges in They can tolerate wide ranges in

temperature, salinity and even desiccationtemperature, salinity and even desiccation– Can be found in many areas including near Can be found in many areas including near

hydrothermal vents and salt flats (two very hydrothermal vents and salt flats (two very extreme environments)extreme environments)

ProkaryotesProkaryotes• Special Features of Bacteria:Special Features of Bacteria:• A variety of shapes including ____, ____, A variety of shapes including ____, ____,

and ____and ____• Cell wall structure is semi-rigid, but Cell wall structure is semi-rigid, but

permeable; Made of polysaccharide permeable; Made of polysaccharide called peptidoglycancalled peptidoglycan

• Wide variety of metabolic typesWide variety of metabolic types• Very abundant worldwideVery abundant worldwide

ProkaryotesProkaryotes

• Special Features of Bacteria:Special Features of Bacteria:– One of the most important functions of One of the most important functions of

bacteria in the marine community is to break bacteria in the marine community is to break down dead organic matter – this forms detritus, down dead organic matter – this forms detritus, which are minute particles of organic matter which are minute particles of organic matter now available as nutrition for other organismsnow available as nutrition for other organisms

– Cyanobacteria are a group of photosynthetic Cyanobacteria are a group of photosynthetic bacteria that are extremely important in food bacteria that are extremely important in food chains producing glucose and fixing nitrogen chains producing glucose and fixing nitrogen

– Stromatolites, massive calcareous mounds Stromatolites, massive calcareous mounds formed by cyanobacteria, have been found formed by cyanobacteria, have been found that are over a billion years oldthat are over a billion years old

stromatolites

ProkaryotesProkaryotes

• Metabolic diversity:Metabolic diversity:

• Photosynthesis – derive energy from Photosynthesis – derive energy from lightlight

• Chemosynthetic – derive energy from Chemosynthetic – derive energy from chemical compoundschemical compounds

• Heterotrophs – derive energy from Heterotrophs – derive energy from organic matter by respirationorganic matter by respiration

DiatomsDiatoms• Diatoms:Diatoms:

– Photosynthetic Photosynthetic – Yellow-brown color in life is a result of photosynthetic Yellow-brown color in life is a result of photosynthetic

pigments- chlorophyll (A and C) and carotenoidspigments- chlorophyll (A and C) and carotenoids– Cell wall of silica called a frustule forms a complete Cell wall of silica called a frustule forms a complete

cover called thecacover called theca– When die, frustules accumulate forming diatomaceous When die, frustules accumulate forming diatomaceous

earth used as abrasive, for filtering and as pesticideearth used as abrasive, for filtering and as pesticide– Most important primary producer on Earth Most important primary producer on Earth – Mostly unicellular but some form coloniesMostly unicellular but some form colonies

DiatomsDiatoms

• DiatomsDiatoms– Around half of the 12,000 known species are marineAround half of the 12,000 known species are marine– Most are planktonicMost are planktonic– Store excess energy as an oil which also aids in Store excess energy as an oil which also aids in

buoyancybuoyancy– Tiny pores in frustule used for gas/nutrient exchange. Tiny pores in frustule used for gas/nutrient exchange. – Some produce a toxin, known as domoic acid, that can Some produce a toxin, known as domoic acid, that can

accumulate in the tissues or organisms that eat accumulate in the tissues or organisms that eat diatoms such as shellfish and small fishdiatoms such as shellfish and small fish

– Larger organisms that eat these shellfish or small fish Larger organisms that eat these shellfish or small fish can become ill or die from this accumulated toxin =can become ill or die from this accumulated toxin =

Biomagnification or bioaccumulationBiomagnification or bioaccumulation

DiatomsDiatoms

• DiatomsDiatoms– Mainly reproduce by cellular division (a form of Mainly reproduce by cellular division (a form of

asexual reproduction)asexual reproduction)– In this type of reproduction, the cell divides and In this type of reproduction, the cell divides and

each result cell gets one-half of the frustule.each result cell gets one-half of the frustule.– This cell now must secrete the other half of the This cell now must secrete the other half of the

frustule (smaller piece of epi- or hypotheca)frustule (smaller piece of epi- or hypotheca)– Due to this, diatoms get smaller each time they Due to this, diatoms get smaller each time they

reproducereproduce– To restore normal size, they must either sexual To restore normal size, they must either sexual

reproduce or cast off the frustule and secrete an reproduce or cast off the frustule and secrete an entire new frustuleentire new frustule

DinoflagellatesDinoflagellates

• DinoflagellatesDinoflagellates– Most species live in marine environmentMost species live in marine environment– Mostly photosynthetic, some can ingest particlesMostly photosynthetic, some can ingest particles– Each species has unique shape reinforced by Each species has unique shape reinforced by

plates of a polysaccharide called cellulose to plates of a polysaccharide called cellulose to form thecaform theca

– Two flagella in grooves on body that produce Two flagella in grooves on body that produce motionmotion

– Also reproduce by cellular divisionAlso reproduce by cellular division– Some are ____ (Have you ever noticed the Some are ____ (Have you ever noticed the

greenish glow as you wade in the Gulf?)greenish glow as you wade in the Gulf?)

Dinoflagellates

DinoflagellatesDinoflagellates

• DinoflagellatesDinoflagellates– Zooxanthellae are important Zooxanthellae are important

dinoflagellates that live in a symbiotic dinoflagellates that live in a symbiotic relationship with corals, sea anemones relationship with corals, sea anemones and other organisms (many of these and other organisms (many of these host organisms have little or no growth host organisms have little or no growth without their symbiotic partner)without their symbiotic partner)

Algal BloomsAlgal Blooms

• Diatoms and dinoflagellates can go Diatoms and dinoflagellates can go through periods of rapid growth through periods of rapid growth known as “blooms”known as “blooms”

• This is a result of high levels of This is a result of high levels of nutrients in the waternutrients in the water

• These blooms can be harmful to These blooms can be harmful to marine organisms and even people marine organisms and even people at timesat times

DinoflagellatesDinoflagellates

• DinoflagellatesDinoflagellates– A few species lack chloroplasts and live as A few species lack chloroplasts and live as

parasites in marine organismsparasites in marine organisms– Some species can reproduce in larger numbers Some species can reproduce in larger numbers

and produce a “Red Tide” and produce a “Red Tide” – PfiesteriaPfiesteria is a dinoflagellate that produces very is a dinoflagellate that produces very

serious toxins that can cause massive fish kills, serious toxins that can cause massive fish kills, harm shellfish and impair the nervous system harm shellfish and impair the nervous system in humans.in humans.

– PfiesteriaPfiesteria was discovered near the Outer Banks was discovered near the Outer Banks in North Carolinain North Carolina

Dinoflagellates often cause Dinoflagellates often cause red tidesred tides

ProtozoaProtozoa

• Foraminiferans (forams) Foraminiferans (forams) – Exclusively found in marine communityExclusively found in marine community– Found on sandy or rocky bottoms Found on sandy or rocky bottoms – Tests (shell) of calcium carbonateTests (shell) of calcium carbonate– Can be important contributors of calcareous Can be important contributors of calcareous

material on coral reefs or sandy beachesmaterial on coral reefs or sandy beaches– ____ (false feet) extend through pores in the ____ (false feet) extend through pores in the

shell where they are used to capture minute shell where they are used to capture minute food particles such as phytoplanktonfood particles such as phytoplankton

Foraminiferans thin pointed pseudopods in ___ tests.

ProtozoaProtozoa

• RadiolariansRadiolarians– Planktonic, mostly microscopic, although Planktonic, mostly microscopic, although

a few can reach large sizesa few can reach large sizes– test of silicatest of silica– Like forams, they use pseudopods that Like forams, they use pseudopods that

extend through pores in the shell where extend through pores in the shell where they are used to capture minute food they are used to capture minute food particles such as phytoplanktonparticles such as phytoplankton

Radiolarian

ProtozoaProtozoa

• CiliatesCiliates– ____ present for locomotion____ present for locomotion– Most live as solitary cellsMost live as solitary cells– Some build tests made of organic Some build tests made of organic

debrisdebris– May live on hard substrateMay live on hard substrate– Some are planktonicSome are planktonic

Ciliate

FungiFungi

• Eukaryotic and mostly multicellularEukaryotic and mostly multicellular

• Heterotrophic with unique cell walls Heterotrophic with unique cell walls made of polysaccharide called chitinmade of polysaccharide called chitin

• Most of the 1500 species of marine Most of the 1500 species of marine fungi are microscopicfungi are microscopic

FungiFungi

• Like bacteria, many fungi break Like bacteria, many fungi break down dead organic matter into down dead organic matter into detritusdetritus

• Some fungi live in symbiosis with Some fungi live in symbiosis with cyanobacteria, these are known as cyanobacteria, these are known as lichenslichens

• Marine lichens often live in wave-Marine lichens often live in wave-splashed areas of rocky shorelines splashed areas of rocky shorelines and other hard substrate and other hard substrate

Marine lichens

Most Important Most Important Characteristics of Marine Characteristics of Marine

MicrobesMicrobes