Topic: BIO-02 Complete Glossary of Key Terms

Activated Sludge: Microbial biomass (floc of aerobic bacteria and protozoa) formed in aeration tanks during secondary sewage treatment; a portion is recycled as inoculum, and the rest undergoes anaerobic digestion.

Aerobic: Requiring or using molecular oxygen ($O_{2}$). Secondary sewage treatment (aeration tanks) is aerobic.

Anaerobic: Occurring without molecular oxygen. Anaerobic digestion by methanogens occurs in the absence of $O_{2}$.

Antibiotic: A substance produced by a microorganism that kills or inhibits other microorganisms. Examples: penicillin, streptomycin, erythromycin, tetracycline.

Bioactive Molecule: A biologically active compound (not strictly an antibiotic or enzyme) that modulates physiological processes. Examples: lovastatin, cyclosporin A.

Biofertilizer: A preparation containing living microorganisms that promote plant growth by increasing nutrient availability through nitrogen fixation, phosphorus solubilization, or other mechanisms.

Biogas: A mixture of gases (primarily methane ~65%, C$O_{2}$ ~30%, $H_{2}S$ trace) produced by anaerobic microbial digestion of organic matter. Used as a renewable fuel.

Biological Control (Biocontrol): The use of living organisms or their products to suppress pest populations. Examples: Bt, NPV, Trichoderma, ladybird beetles.

BOD (Biochemical Oxygen Demand): The amount of dissolved oxygen consumed by microorganisms decomposing organic matter in water at 20°C over 5 days. Indicator of water pollution.

Cry Proteins: Crystalline insecticidal proteins (Cry1Ac, Cry2Ab) produced by Bacillus thuringiensis, toxic specifically to lepidopteran insect larvae.

Cyclosporin A: A cyclic undecapeptide immunosuppressant produced by Trichoderma polysporum; inhibits calcineurin, blocking T-cell activation.

Heterocyst: Specialized differentiated cell in filamentous cyanobacteria (Anabaena, Nostoc) lacking Photosystem II, providing an $O_{2}$-poor environment for nitrogenase-mediated nitrogen fixation.

Leghemoglobin: An oxygen-buffering protein in legume root nodules that regulates $O_{2}$ supply to Rhizobium bacteroids, enabling nitrogenase to function.

Lovastatin: A statin bioactive molecule produced by Monascus purpureus that competitively inhibits HMG-CoA reductase, reducing cholesterol biosynthesis.

Methanogen: An anaerobic archaeon (e.g., Methanobacterium) that produces methane ($CH_{4}$) via methanogenesis during anaerobic digestion of organic matter.

Mycorrhiza: A mutualistic fungus-root symbiosis (e.g., Glomus) that primarily enhances plant phosphorus absorption through extensive hyphal networks.

Nitrogenase: The enzyme complex in nitrogen-fixing prokaryotes that catalyzes the reduction of atmospheric $N_{2}$ to ammonia ($NH_{3}$); irreversibly inactivated by $O_{2}$.

NPV (Nucleopolyhedrovirus): A baculovirus with high species-specificity used as a biological control agent against insect pests; does not harm non-target organisms.

Primary Effluent: The liquid overflow from primary sedimentation during sewage treatment, which then enters secondary (biological) treatment.

Primary Sludge: Settled solid material (organic and inorganic particles) collected during primary sedimentation in sewage treatment.

Root Nodule: A swelling on legume roots containing symbiotic Rhizobium bacteria that fix atmospheric nitrogen for the plant.

Statin: A class of bioactive molecules (e.g., lovastatin, simvastatin) that inhibit HMG-CoA reductase, lowering cholesterol synthesis in liver cells.

Streptokinase: A thrombolytic enzyme produced by Streptococcus that activates plasminogen to plasmin, dissolving fibrin clots. NOT an antibiotic.

Thrombolytic: Causing dissolution of a blood clot (thrombus). Streptokinase is the microbial thrombolytic agent in BIO-02.