Whey generated during cheese and fermented dairy product manufacturing is the primary reservoir and most dangerous source of bacteriophages in dairy plants. During fermentation, phages replicate to astronomical numbers ($\gt 10^9\text{ PFU/mL}$) within infected starter lactic acid bacteria; aerosolization of whey during separation, storage, or spillage disseminates phages throughout the facility.

Statement (I) is true: trace levels of antibiotic residues (even 0.005 IU/mL of penicillin) inhibit lactic acid starter bacteria, retarding acidification. Statement (II) is false: residual chemical detergents and sanitizers (such as quaternary ammonium compounds, chlorine, iodophors) rinsed improperly from dairy vats and pipes exert strong bacteriostatic or bactericidal action on starter cultures, severely inhibiting starter activity.

Bacteriocin classification among Lactic Acid Bacteria:

• Lactococcus lactis produces Nisin and Lacticin.
• Lactobacillus casei produces Caseicin.
• Lactobacillus brevis produces Brevicin.
• Lactobacillus acidophilus produces classical bacteriocins and antimicrobial peptides including Lactocidin (first isolated by Vincent et al., 1959), Acidophilin, and Acidolin, which exhibit broad-spectrum antagonistic activity against pathogenic and food spoilage bacteria in the mammalian gastrointestinal tract.