7.2 Minimal Genome Criteria

Minimal Genome Criteria refers to the specific, testable standards that a genome must satisfy to be considered minimal, translating the general concept of minimal genome scope into concrete, verifiable conditions. These criteria include possessing the required function set, preserving viability, sustaining propagation, achieving sufficiency under defined conditions, demonstrating irreducibility through deletion testing, maintaining information completeness, meeting a stability requirement, satisfying a growth threshold, and being accompanied by a clearly specified claim.

Minimal Genome Required Function Set

The Genes That Must Be Present

Minimal genome required function set specifies the particular biological functions — such as replication, transcription, translation, and core metabolism — that the genome must encode for the resulting cell to be viable under its defined conditions.

Basis for Judging Sufficiency

This required set forms the basis against which the actual gene content of a candidate minimal genome is judged, since the genome must encode at least these functions, even if it encodes little else.

Minimal Genome Viability Preservation

Confirming Life Can Still Be Sustained

Minimal genome viability preservation requires that a candidate genome, once implemented in an actual cell, be experimentally confirmed to sustain a living, functioning organism rather than remaining a theoretical construct.

Central, Non-Negotiable Criterion

This preservation is the central, non-negotiable criterion among all minimal genome criteria, since a genome that fails to sustain viability cannot be considered minimal regardless of how small or well-designed it appears on paper.

Minimal Genome Sustained Propagation

The Genome Must Support Ongoing Reproduction

Minimal genome sustained propagation requires that the candidate genome support not just a single generation of viability but repeated cell division across multiple generations, producing consistently viable offspring.

Distinguishing From Transient Viability

This criterion distinguishes a genuinely minimal genome from one that might sustain a cell briefly but fails to support the ongoing reproduction needed for meaningful long-term study.

Minimal Genome Defined-Condition Sufficiency

Adequate Only Under Stated Conditions

Minimal genome defined-condition sufficiency requires that the genome be demonstrated to be adequate specifically under the environmental and nutritional conditions stated for the project, without any claim extending beyond those conditions.

Necessity of Testing Under the Stated Conditions

This criterion requires that sufficiency actually be tested under the specific conditions claimed, rather than assumed based on performance under different or more permissive conditions.

Minimal Genome Deletion Irreducibility

No Further Gene Can Be Safely Removed

Minimal genome deletion irreducibility requires demonstrating that no further gene can be deleted from the candidate genome without losing viability under the stated conditions, establishing that the genome has reached a true reduction endpoint rather than an arbitrary stopping point.

Testing Method for This Criterion

This irreducibility is typically established through systematic deletion testing of remaining genes, confirming that each one, individually, proves necessary for continued viability.

Minimal Genome Information Completeness

All Necessary Genetic Information Is Present

Minimal genome information completeness requires that the genome contain all the genetic information necessary for its required functions, without gaps or missing elements that would otherwise be compensated for by an unaccounted external source.

Guarding Against Hidden Dependencies

This criterion guards against a scenario in which apparent minimality is achieved only because some necessary genetic information has been inadvertently supplied externally rather than encoded within the genome itself.

Minimal Genome Stability Requirement

The Genome Must Remain Consistent Over Time

Minimal genome stability requirement specifies that the candidate genome must remain structurally and functionally consistent across generations, without significant unplanned mutation or rearrangement that would alter its minimal status.

Relevance to Long-Term Minimality Claims

This requirement ensures that a genome confirmed as minimal at one point in time can be relied upon to remain minimal, and viable, throughout subsequent use and propagation.

Minimal Genome Growth Threshold

A Baseline Level of Growth Performance

Minimal genome growth threshold specifies a minimum acceptable level of growth performance that the resulting cell must achieve, distinguishing genomes that merely allow survival from those that support meaningful, sustained growth.

Setting an Appropriate Threshold

The specific threshold used depends on the goals of a given project, but its inclusion ensures that minimal genome status is not granted to a genome that produces a cell too impaired to grow at a useful rate.

Minimal Genome Claim Specification

Documenting Exactly What Is Being Claimed

Minimal genome claim specification requires that any assertion of minimal genome status be accompanied by a clear statement of the chassis organism, environmental conditions, required function set, and testing methodology used to support that assertion.

Preventing Ambiguous or Overstated Claims

This specification prevents ambiguity or overstatement, ensuring that anyone evaluating a minimal genome claim can understand precisely what was tested, under what conditions, and against what criteria the claim of minimality was established.