May 1


Wild Bacteria Starter Cultures & the Phages that Eat Them

“The Ganges is so dirty even microbes can’t live in it.” S. Clemens

Level: Advanced

In this rambling post you will find 

  • What is Phage
  • Why is it controversial
  • That both sides of the debate have their points
  • Quotes and links to interesting articles on phage therapy
  • That the Ganges is so filthy that the natural balance evolved viral phages to keep it under control.

Definition of Phage
PHAGE : A bacteriophage is a virus that infects bacteria. (from 'bacteria' and Greek phagein, 'to eat') (Wikipedia)

Why is it Controversial?
Phage is a concern for cheesemakers using modern industrial techniques, particularly with pasteurized milk. It can attack starter cultures and change them, slow them down, or make them useless. This leads to unpredictable variations in flavor and texture. Sometimes to a completely different cheese.

In the latter part of the 20th Century there were some catastrophic phage attacks on cheese. They were due to the improper use of direct to vat cultures. Lacking expertise, yet creative, these producers made batch cultures with these "domesticated" laboratory cultures. Some domesticated starter cultures are more prone to phage, like Flora Danica, the victim of the worst of these attacks. Producers lost a great deal of money. Fear of Phage became a syndrome that continued up until today.

Wild Cultures use natural bacteria present in raw milk, and the local environment. Domesticated Culture you buy from a laboratory which isolates bacteria and innoculate sterile milk to incubate them in controlled laboratory conditions.

Some say you are gambling if you use wild rather than laboratory cultures. Others, you may never get a truly world class cheese if you do not use wild cultures.

Culture controls which bacteria of the many present in milk will thrive. Before laboratory cultures, cheesemakers would start the season without any culture. Allowing a culture to develop from the microbes in the local environment.

They would then use this “Mother Culture” to inoculate the daily make. They refreshed the “Mother Culture” with fresh milk daily.

Today, the super-sanitized environment of the cheese room has led to a loss of microbial diversity. Along with the industrialization of how we feed our animals.

Laboratory culture mimics nature as best it can. Cheesemakers use specific cultures to replace those missing from the milk, either due to pasteurization, or to create the outcome they want for their cheese.

“Many problems with phages have to do with to the improper use of direct cultures. [DS -this means used to create batch cultures rather than direct into a batch of cheese.]”

Prof. Jorge Rynheimer, Argentina

“The challenge with wild cultures is the variation in rates of acid production. But cultures with pasteurized milk and laboratory cultures are more prone to phage. 

An Italian cheese plant I know of solved the problem. They use yesterday’s whey to inoculate heat-treated whey to produce batch culture. They use this culture along side a commercial direct vat set daily.”

Neville McNaughton

“The traditional way (of making cheese) started with milk. The LAB (lactic acid bacteria-DS) naturally present in milk. If you do not pasteurize it will acidify. Then you can use this coagulated milk to inoculate a new batch. The batcjes that make the best product you can grow in bigger portions and use them until they begin to slow down. The traditional dairies used to add whey to the cultures to make it more resistant to phages. Starter cultures developed in this way were often very good. That is, until the wide spread use of antibiotics in cows began to kill the starters.”

Dr. Lyette Josephson, Denmark

“I can give you a reference on phages in traditional cheddar cheese. A few times a year producers cultivate a wild starter (undefined in her words- DS). They leave milk out overnight to let it sour. They then divide it into small batches for making the cultures they will use with the cheese milk. 

Prof. Lytte Josephsen, Denmark:

The reference is :
Nielsen, E. W. 1998. Long-term use of a cheddar starter and development of phages with homology to its bacteria.
 International Dairy Journal 8:1003-1009

Bella Italia

In Italy, an interesting solution evolved. Some of their appelation controlled cheeses (DOC) allow for the best of both worlds. Preserving unique regional flavors, and more dependable phage resistant acid production. The dominant bacteria comes from a local laboratory. It is a local bacteria, cultivated only in the same region. The cheesemaker uses this to make culture with raw milk. The process is less prone to phage because the complexity of bacteria in the raw milk.

Outside of the Cheeseworld, in fact, Phages are more popular. Doctors use them in the treatment of antibiotic resistant bacteria. Recently, against lysteria in meat. (see the link below)

The following tidbits...

on wild cultures in Italian cheesemaking come from Professors Germano Mucchetti and Erasmo Nevian of the Instituto Sperimentale Lattiero Caseario, Lodi, Italy.

“Dear Dan,
In Italy a lot of cheeses use raw milk and “natural” starters. Parmigiano Reggiano and Grana Padano (the parents of the globalized “Parmesan”) in particular. Their whey cultures are the most studied and well known. Composed of thermophilic lactobacilli, and sometimes, a minor component of streptococci.

Cultures the production of other raw and/or artisanal cheeses use whole milk or whey. The “milk starters” (lattoinnesto in Italian) are microbial cultures derived from the heat treatment (60-65°C per 10-20 min) of fresh raw milk, then cooled to 42-45°C and incubated at those temperatures until pH drop to 5-5,4 (generally within a time ranging from 6 to 18 hours). Their flora is a natural mix of biotypes of Streptococcus termophilus, with the presence of some enterococci, if they occur in the raw milk.

Traditional Mozzarella cheeses use this kind of culture. (e.g. Mozzarella Tradizionale.) You can see on the web at

It is the standard of production for mountain cheeses like Montasio, some varieties of Pecorino (sheep) cheeses and many industrial soft cheeses, like Crescenza etc.

Whey starters, (sieroinnesto in Italian), are microbial cultures made from whey. The whey comes from yesterday's batch of cheese. To make the cheese, they add the whey to the milk. Then they let it incubate it at the opportune temperature. It is specific to every cheese. They incubate until the batch reaches the right degree of acidity.

We do things differently than the USA, as we suppose you well know. In Italy, many culture laboratories produce “natural” or “undefined” cultures for the artisanal cheeses as well.

The approach however, depending on many local variables, may be very different: when it is economically feasible, a culture laboratory offers to the cheesemaker a ready to use liquid culture. This culture provides a functional mix of viable cells, lactic acid and, may be, aroma from the original, while avoiding drastic changes (variability in acid production) in the cheesemaking technology.”

In other cases, a smaller local laboratory can produce direct to vat starters, composed by strains isolated from milk, cheese and/or natural starters typical of that variety of cheese.

For the cheesemaker, when these cultures are available, the choice is between the cost of buying something that was inexpensive or less variability. As self-produced starter is by nature more variable.
The problem, for Italian artisanal cheesemakers, is to reduce the range of variability. Natural cultures are a strong instrument to assess the imprinting of the cheese and to link cheese with its local origins, the producer, and the community they live in (TERROIR). But, there is an economic risk that comes with an excess of variability. It leads cheeses that do not have the traditional characteristics associated with them. (a mix of good, normal and defective cheeses).

In Italy some combine the use of natural cultures with selected ones. The former improves the aroma of the cheese, and the latter produces lactic acid.“


Germano Mucchetti and Erasmo Neviani

Phage in Medicine:

Eastern Europe continued to use Phage in medicine during the Cold War. This was because of a lack of money. Continuing the early research in phage therapy abandoned by the west, in our love affair with antibiotics. Thier work was only rediscovered after the fall of the Soviets.

For two fascinating articles on this phage therapy please go to sciencemag.htm

So What does it all Mean?

There is a greater potential for flavor, particularly complexity of flavor, if you use raw milk and natural wild starter to make cheese. However, there is a greater potential for variability in acid production. This will change the kind of cheese you end up making.

Like the Italians, if you are using raw milk, you could isolate the acid producers in a lab, then use with a wild starter for flavor: a kind of hybrid. But, if using pasteurized milk, you risk phage attacks, and the loss of your starter. With pasteurized milk it is best to use direct set, direct to vat cultures, even in the case of whey cultures, as they do not work in pasteurized milk.

The more you know the better cheese tastes!

There is no greater joy than sharing a taste of delicious cheese with your friends and family, except being able to share the story of the cheese, how it was made, and knowing exactly what to pair it with. Take the Ultimate Cheese Course... ONLINE!  Learn everything you need to grow from an enthusiastic cheese lover, to a true Turophile,  a Cheese Master.


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    • Thanks for the comment, will write strains. But is a bit dramatic. There are many cheeses made with wild cultures throughout the world. While they will vary a bit they are hardly a Russian roulette. There has been a lot of study in Italy on their use in Grana Padano. In Brasil, all traditional and most artisanal cheeses are made with wild starter cultures. They vary a bit according to the season, but subtly. The weather is really more of an influence on which strains predominate as they do not use refrigeration.

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