Week 14 (Monday, 1st June 2015)

Today is the last class of Microbiology II with Dr. Wan for this semester. We started the first class in BMF (Bilik Mesyuarat Fakulti) and we ended here as well. Such a memorable thing for us to remember hehe.

We finished the last two topics which are Biogeochemical Cycles and Aspect of Biotechnology in Microbial Ecology.

BIOGEOCHEMICAL CYCLES

·         Definition: mechanism by which recycling of nutrients occur

·         Characteristics: 1) transformed and cycled through redox reaction   2) all cycles are linked

·         Cycles: 1) carbon     2) nitrogen     3) sulfur     4) iron     5) mangase

1) Carbon cyle

Forms: 1) reduced – methane, organic matter   2) oxidized – CO, CO2

§        Fixer: 1) plants     2) photosynthetic bacteria (cynobacteria, green algae)

§         Aerobically à respiration à CO2 released

§        Anaerobically à respiration/fermentation à CO2, H2, CH4 produced

2) Nitrogen cycle

§       Processes: 1) nitrification   2) denitrification   3) nitrogen fixation

§        1) Nitrification – aerobic (ammonium ion à nitrite à nitrate)

§        2) Dinitrification – dissimilatory (use nitrate as electron acceptor to produce ATP)

-            anaerobic  (by Pseudomonas)

-            products: nitrogen gas, nitrous oxide, nitrite

§         3) N2 fixation – reductive process which produce ammonia

-          Aerobic/anaerobic prokaryotes

3) Sulfur cycle

Process: 1) sulfur oxidation   2) sulfur reduction   3) sulfate reduction

§        1) sulfur oxidation – produce sulphate by using sulfide as e- source

-               Thiobacillus

§        Sulfur reduction – sulfate à sulfide (Desulfovibrio, Desulfuromonas)

-          Sulfite àsulfide (Clostridium, Desulfovibrio)

§        Sulfate reduction – reduction of sulfate for use in amino acids and protein biosynthesis

4) Iron cycle

§       Oxidation – ferrous ion àferric ion (aerobic)

§        Reduction – ferric ion à ferrous ion (anaerobic)

5) Manganese cycle

§        Aerobic – manganese ion à manganic ion

§       Anaerobic – manganic ion à manganese ion

ASPECT OF BIOTECHNOLOGY IN MICROBIAL ECOLOGY

1) M/organism as pollutants – food/waterborne phatogens

                                                        -  eutrophication

2) M/organism as pollution – elemental mercury, organic compounds of mercury

                                                      - not recycle

                                                      - inhibit enzyme when combine with sulfyhydryl group of protein

3) M/organism as indicator of pollution – test for water pollution

                                                                              - E. coli, E. aerogenes

4) M/organism may reduce pollution – add into soil or plants to improve crop production

                                                                         - carry out biodegradation, bioremediation

·         Biodegradable – natural decomposition of molecule by microorganism

        Non-biodegradable = recalcitrant

·         Microbial application as pesticide – DDT

      Microbial application as insecticide – Bt

·         Bioremediation – use of living organism to  promote degradation of environmental pollutants

·         Cometabolism – addition of easily metabolized organic matter to increase biodegradation of recalcitrant compounds that are not use a C and energy sources by microorganism

·         Phytoremediation – use of plants to stimulate the degradation, transformation or removal of                                                  compound, either directly or in conjuction with microorganism

·                                                                  – phytoextraction, phytodegradation, rhizofilteration, phytostabilization,                                                    phytovolatilation