Growth kinetics history: in which year did Jacques Monod first propose the functional relationship between specific growth rate and limiting substrate concentration now known as the Monod equation?

Introduction / Context:
The Monod equation relates specific growth rate μ to limiting substrate concentration S via μ = μmax * S / (Ks + S). It is foundational in bioprocess design, chemostat analysis, and environmental modeling. This question asks for the historical year of Monod’s initial proposal.

Given Data / Assumptions:

• We focus on the first proposal, not later reviews.
• Options cluster around the 1940s–1950s when microbial growth kinetics matured.
• The correct answer reflects Monod’s early doctoral work and publications.

Concept / Approach:
Monod’s early 1940s research characterized bacterial growth as a function of substrate concentration, leading to the hyperbolic form analogous to Michaelis–Menten kinetics. While a seminal 1949 English-language paper popularized the relationship, the original formulation traces to 1942 in Monod’s earlier publications.

Step-by-Step Solution:

Verification / Alternative check:
Historical reviews attribute the first articulation to Monod’s 1942 work, with subsequent refinement and popularization in 1949; textbooks sometimes cite both years with context.

Why Other Options Are Wrong:

• 1946, 1950, 1958, 1966: postdate the original proposal or refer to later developments.

Common Pitfalls:
Confusing first proposal (1942) with the widely cited 1949 paper; mixing Ks with KM—similar form, different physical meaning.

Final Answer:
1942