Koji manufacture (starter for soy sauces and miso): The most important organism(s) involved in koji production is/are which of the following?

Introduction / Context:
Koji is a mold-cultured grain (often rice or wheat) that serves as the enzyme-rich starter for Japanese fermentations such as soy sauce, miso, and sake. The mold must secrete powerful amylases and proteases to saccharify starches and hydrolyze proteins, preparing substrates for subsequent fermentations.

Given Data / Assumptions:

• We identify the principal koji molds used traditionally and industrially.
• Organisms must be safe, high enzyme producers, and well-adapted to solid-state culture.

Concept / Approach:
Aspergillus oryzae and Aspergillus sojae are the two classic koji molds. They produce amylases, proteases, and peptidases essential for generating sugars, peptides, and amino acids that later yeasts and bacteria transform into flavor and aroma compounds. These Aspergillus strains are domesticated, with long histories of safe use.

Step-by-Step Solution:
List candidate organisms and their roles. Associate Aspergillus oryzae/sojae with koji enzyme production. Exclude lactic bacteria and other molds not central to koji. Choose the combined option “Both (a) and (b).”

Verification / Alternative check:
Traditional manuals and modern factories alike rely on A. oryzae/sojae for controlled koji growth and enzyme release at 28–35 °C with careful aeration and moisture control.

Why Other Options Are Wrong:

• Lactococcus lactis: Dairy starter; not a koji mold.
• Rhizopus oligosporus: Used for tempeh fermentation of soybeans, not koji.

Common Pitfalls:
Confusing koji with tempeh or misidentifying koji as a yeast culture; koji is primarily a filamentous mold culture.

Final Answer:
Both (a) and (b) — Aspergillus oryzae and Aspergillus sojae — are the key koji molds.