Overview

Fermented dairy products like yogurt, cheese, and kefir are rich sources of beneficial bacteria, not only in their impressive quantities but also in their remarkable adaptability to the human gut microbiome. These probiotics help maintain a healthy balance of gut flora, enhancing digestion and overall well-being. In this article, we provide a detailed breakdown of the probiotic bacteria present in various fermented dairy products, highlighting their typical ratios and how they contribute to a resilient and adaptable gut environment. We also compare to kimchi, a popular fermented probiotic-filled vegetable blend that has been found to help detoxify microplastics, and is sold by some companies for this purpose: Science Daily Article

Whether you’re a probiotic enthusiast or simply curious about nourishing your microbiome, this information offers valuable insights into the probiotic power of dairy.

1. Yogurt

Mandatory Starter Cultures (FDA Required)

According to FDA regulations, all yogurt must contain:

• Lactobacillus delbrueckii subsp. bulgaricus (L. bulgaricus)
• Streptococcus thermophilus (S. thermophilus)

Standard Yogurt Composition

Minimum CFU Level: 10⁷ CFU/g (per Codex Alimentarius)

Bacterial Species Present:

• Lactobacillus acidophilus
• Bifidobacterium lactis
• Lactobacillus casei
• Lactobacillus rhamnosus

Typical Multi-Strain Yogurt Example (11-strain formulation)

1. Bifidobacterium lactis - ~10%
2. S. thermophilus - ~15-20%
3. L. casei - ~8-10%
4. L. rhamnosus - ~8-10%
5. L. acidophilus - ~10-12%
6. L. delbrueckii subsp. lactis - ~5-7%
7. L. delbrueckii subsp. bulgaricus - ~10-15%
8. Lactococcus lactis subsp. cremoris - ~5-7%
9. Lactococcus lactis subsp. lactis - ~5-7%
10. Lactococcus lactis subsp. lactis biovar diacetylactis - ~3-5%
11. Leuconostoc mesenteroides subsp. cremoris - ~3-5%

Total CFU Count: Hundreds of billions per serving

2. Kefir

Most Complex Fermented Product

Kefir contains significantly more probiotic diversity than yogurt due to its traditional preparation with kefir grains or mixed starter cultures.

Kefir Grains Composition (per gram)

• Lactic Acid Bacteria (LAB): 10⁸ CFU/g
• Yeasts: 10⁶-10⁷ CFU/g
• Acetic Acid Bacteria (AAB): 10⁵ CFU/g

Bacterial Species in Kefir

Primary Lactobacillus Species (by proportion):

• Lactobacillus kefiri - ~80% of total Lactobacillus
• Lactobacillus paracasei ssp. paracasei - ~5-10%
• Lactobacillus acidophilus - ~3-5%
• Lactobacillus delbrueckii ssp. bulgaricus - ~2-3%
• Lactobacillus plantarum - ~1-2%
• Lactobacillus kefiranofaciens - ~1-2% (produces kefiran)

Other Bacterial Species:

• Lactococcus lactis - Variable (major species)
• Leuconostoc mesenteroides - Variable
• Streptococcus thermophilus - Minor component
• Acetobacter aceti
• Acetobacter rasens

Yeast Species in Kefir

• Saccharomyces cerevisiae - Most abundant
• Saccharomyces unisporus
• Candida kefyr
• Kluyveromyces marxianus spp. marxianus

Typical CFU Counts in Finished Kefir

• Commercial Kefir: 25-50 billion CFU per cup
• Kefir from Grains: 100-300 billion CFU per cup (or higher)
• Water Kefir: 5-35 billion CFU per cup

Total Probiotic Species: 10-61 different strains (depending on source and production method)

3. Cheddar Cheese

Primary LAB Species in Aged Cheddar

• Lactobacillus paracasei - Major species during ripening
• Lactobacillus casei - Significant component
• Lactobacillus rhamnosus - Present and acid-resistant
• Lactobacillus helveticus - Secondary species
• Lactococcus lactis - Starter culture (decreases during ripening)

Nonstarter Lactic Acid Bacteria (NSLAB)

During ripening (typically 6+ months), NSLAB proliferate:

• Lactobacillus species become dominant
• Can reach levels >10⁷ CFU/g

Probiotic Strains Added (in Probiotic Cheddar formulations)

• Lactobacillus acidophilus LA-5 - Often added strains
• Bifidobacterium animalis subsp. lactis BB-12 - Acid and bile-resistant
• Pediococcus acidilactici AS185 - Novel adjunct cultures

CFU Levels in Mature Cheddar

Typical naturally-ripened: 10⁷-10⁸ CFU/g

Probiotic formulations: Designed to maintain viable counts throughout ripening

4. Goat Cheese (Chèvre)

Fermentation Characteristics

Goat cheese production varies widely based on traditional methods and pasteurization. Fresh goat cheese offers different probiotic profiles than aged varieties.

Primary LAB Species

• Lactobacillus plantarum - Often isolated and used as probiotic adjunct
• Lactobacillus acidophilus - Naturally present
• Lactobacillus casei - Variable presence
• Lactococcus lactis - Starter culture component

Probiotic Adjunct Cultures (in Probiotic Formulations)

When specifically formulated as probiotic cheese:

• Lactobacillus plantarum (dairy-product origin strains)
• Typical concentration: 8.6 log CFU/g (lyophilized form)

CFU Levels in Fresh Goat Cheese

• Fresh (8-day shelf life): 10⁷-10⁸ CFU/g
• Example: Probiotic chèvre maintained 7.56 log CFU/g at expiration

Microbial Composition in Fresh Goat Cheese

• Probiotic cultures: 7.56 ± 0.05 log CFU/g
• Starter cultures: 7.81 ± 0.03 log CFU/g
• Yeasts: 5.64 log CFU/g

Note: Fresh goat cheeses have shorter shelf lives and lower ripening times compared to aged varieties, affecting bacterial populations.

5. Manchego Cheese

Type & Origin

Primary LAB in Manchego

Starter Cultures:

• Lactococcus lactis ssp. lactis - Primary acidifier
• Lactococcus lactis ssp. cremoris - Common component
• Leuconostoc mesenteroides ssp. cremoris - Citrate-utilizing species

Natural Microbiota (from raw milk and natural starters):

• Complex consortium of Lactobacillus species
• Various Lactococcus species
• Naturally occurring Leuconostoc strains

Bioactive Bacteria

• Enterococcus faecalis - Produces enterocin 4 (bacteriocin)
• Inhibits L. monocytogenes
• Naturally present in traditional Manchego

Natural Starter Composition

Manchego traditionally uses natural whey starters (NWS) which are:

• Undefined consortia (not single-strain cultures)
• Richer microbial diversity than selected starters
• Co-ferment with raw milk microbiota

CFU Levels

• Typical mature Manchego: High viable LAB counts (exact numbers vary with ripening time)
• Protected by high salt content, low moisture, and acidic pH
• Microbial diversity increases during ripening period

Note: Exact species ratios in Manchego are highly variable due to traditional production methods using natural starters and raw milk microbiota. Commercial vs. artisanal versions differ significantly.

Comparative Summary Table

Important Notes

1. Variability: Actual CFU counts and species ratios vary significantly based on:
   • Production batch
   • Storage time and conditions
   • Individual manufacturer methods
   • Raw material source (milk type and quality)
2. Strain Identification: Many traditional products (especially artisanal cheeses) contain undefined consortia, making exact species identification difficult
3. Live & Active: Products must contain living bacteria at time of consumption for probiotic benefits
4. Label Information: Check product labels for specific strain identification and CFU counts when available
5. Research Variability: Published studies sometimes show conflicting results due to different measurement methodologies and fermentation parameters