Halophilic microbiota of mined salt: Reports on the native microflora of mined salt typically indicate which approximate distribution among common groups?

Introduction / Context:
Even high-salt environments harbor specialized microflora. Understanding the typical composition of microorganisms in mined salt matters for salted food preservation, brine preparation, and quality expectations for traditional curing operations.

Given Data / Assumptions:

• Mined salt contains halotolerant Gram-positive cocci (formerly grouped as Micrococcus), coryneform bacteria, and spore-forming Bacillus spp.
• The question asks for approximate proportions as reported in classical surveys.
• Exact percentages may vary by mine and sampling method; the answer reflects a commonly cited distribution used in exam settings.

Concept / Approach:
The dominance of micrococci in salt reflects their halotolerance and survival on dry crystal surfaces. Coryneforms are also salt-tolerant skin/environmental bacteria, and Bacillus spores persist due to desiccation resistance. A typical textbook distribution lists roughly 70% micrococci, 20% coryneforms, and around 10% Bacillus among isolates.

Step-by-Step Solution:
Recall the classic composition breakdown used in food microbiology curricula. Recognize that micrococci dominate > 50% in mined salt surveys. Select the option that aligns with 70/20/10 proportions.

Verification / Alternative check:
Historical culture-based studies on salt crystals and brines yield high counts of micrococci/coryneforms, with smaller fractions of Bacillus due to spore survival; modern sequencing adds archaea but classical exam answers rely on bacterial groups.

Why Other Options Are Wrong:
Other splits underrepresent micrococci or misstate the Bacillus fraction compared with the commonly taught 70/20/10 pattern.

Common Pitfalls:
Assuming sterility of mined salt; while counts are low, contaminants seed brines and salted foods if hygiene lapses occur.

Final Answer:
70% Micrococcus, 20% coryneforms, and 10% Bacillus.