Navigation Links
New bacteria discovered in raw milk
Date:11/16/2008

Raw milk is illegal in many countries as it can be contaminated with potentially harmful microbes. Contamination can also spoil the milk, making it taste bitter and turn thick and sticky. Now scientists have discovered new species of bacteria that can grow at low temperatures, spoiling raw milk even when it is refrigerated. According to research published in the November issue of the International Journal of Systematic and Evolutionary Microbiology, the microbial population of raw milk is much more complex than previously thought.

"When we looked at the bacteria living in raw milk, we found that many of them had not been identified before," said Dr Malka Halpern from the University of Haifa, Israel. "We have now identified and described one of these bacteria, Chryseobacterium oranimense, which can grow at cold temperatures and secretes enzymes that have the potential to spoil milk."

New technologies are being developed to reduce the initial bacterial counts of pasteurized milk to very low levels. Most enzymes will be denatured at the high temperatures used during pasteurisation, which means they will stop working. However, the heat-stable enzymes made by cold-tolerant bacteria will still affect the flavour quality of fluid milk and its products. Because of this, research into cold-tolerant bacteria and the spoilage enzymes they produce is vital.

"Milk can be contaminated with many different bacteria from the teat of the cow, the udder, milking equipment and the milking environment," said Dr Halpern. "Milk is refrigerated after collection to limit the growth of microbes. During refrigeration, cold-tolerant, or psychrotolerant, bacteria that can grow at 7C dominate the milk flora and play a leading role in milk spoilage. Although we have not yet determined the impact on milk quality of C. oranimense and two other novel species (C. haifense and C. bovis) that were also identified from raw milk samples, the discovery will contribute to our understanding the physiology of these organisms and of the complex environmental processes in which they are involved. There is still a lot to learn about the psychrotolerant bacterial flora of raw milk."

There is an ongoing debate about the benefits and risks of drinking unpasteurised milk. Some people believe the health benefits resulting from the extra nutrient content of raw milk outweigh the risk of ingesting potentially dangerous microbes, such as Mycobacterium bovis, which can cause tuberculosis, and Salmonella species. Because of these risks, many countries have made the sale of unpasteurised milk illegal. Pasteurisation involves heating milk to around 72C for 15-20 seconds in order to reduce the number of microbes in the liquid so they are unlikely to cause disease. Some bacteria produce extracellular enzymes that are remarkably heat tolerant and can resist pasteurisation. Lipase enzymes cause flavour defects and proteases can lead to bitterness and reduced yields of soft cheese.

Raw milk is consumed in rural areas of Europe and is also available in large cities. Distribution of unpasteurised milk is legal in England, Wales and Northern Ireland but illegal in Scotland. There are around 275 establishments in England that are approved by the Food Standards Agency to sell raw milk. However, the green-top bottles must display a warning that indicates the content has not been heat-treated and may contain harmful organisms. Furthermore, farmers are not allowed to sell unpasteurised dairy products if their herd is suspected to be infected with bovine tuberculosis.

"In Israel, dairy companies estimate that cold-tolerant bacteria can cause a 10% loss of milk fats and proteins. When researchers looked at these bacterial communities, they found that 20% of the bacteria isolated were found to be novel species and 5% of these were members of the genus Chryseobacterium," said Dr Halpern. "Because of their effect on milk quality, it is important that we develop sensitive and efficient tools to monitor the presence of these cold-tolerant bacteria."


'/>"/>

Contact: Lucy Goodchild
press@sgm.ac.uk
44-011-898-81843
Society for General Microbiology
Source:Eurekalert

Related biology news :

1. Shuttle brings space-grown strep bacteria back for study
2. The worlds oldest bacteria
3. Bacteria from sponges make new pharmaceuticals
4. Boston University biomedical engineers find chink in bacterias armor
5. University of Leicester scientists discover technique to help friendly bacteria
6. Spaceflight shown to alter ability of bacteria to cause disease
7. A tiny pinch from a z-ring helps bacteria cells divide
8. Legionnaires bacterial proteins work together to survive
9. Scripps research team blocks bacterial communication system to prevent deadly staph infections
10. NSF awards Stevens team $1 million for research on smart, bacteria-repellent nanohydrogels
11. Chemical compound present in detergents produce bacteria alterations in agricultural soils
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:1/12/2017)... 12, 2017  Trovagene, Inc. (NASDAQ: TROV ... today announced that it has signed agreements with seven ... the Middle East for commercialization ... the first wave of international distribution agreements for Trovagene,s ... samples. The initial partners will introduce Trovagene,s ...
(Date:1/11/2017)... 2017  Michael Johnson, co-founder of Visikol Inc. a company originally ... been named to the elite "Forbes 30 Under 30" list in ... people in 20 fields nationwide to be recognized as a leader ... were selected. ... is currently a PhD candidate at Rutgers University. ...
(Date:1/4/2017)... -- For the thousands of attendees at this year,s International Consumer Electronics Show ... biometric measurement devices and services, will be featuring its new line of ... Medical,s special CES Exhibit Suite , the new upper arm and ... WellnessConnected product platform.  Continue ... ...
Breaking Biology News(10 mins):
(Date:1/18/2017)...  Caris Life Sciences, a leading innovator in ... private funder of pancreatic cancer research, are collaborating ... of immunotherapy in the treatment of pancreatic cancer. ... identify potential trial candidates based on biomarker expression ... study investigators. The Lustgarten Foundation is a sponsor ...
(Date:1/18/2017)... Research Future published a half-cooked research report on Global Cancer Diagnostics ... CAGR of 12% during the period 2016 to 2022. ... ... without any control. These abnormal cells have the ability to invade ... spread to other parts of the body through the blood and ...
(Date:1/17/2017)... IA (PRWEB) , ... January 17, 2017 , ... ... China for Balance™ GT soybeans. The new Balance™ GT Soybean Performance System will ... glyphosate and isoxaflutole, the active ingredient in the new Balance® Bean herbicide. The ...
(Date:1/17/2017)... 17, 2017  An international team of researchers ... St. Boniface Hospital Albrechtsen Research Centre/University of Manitoba ... unmet health need affecting nearly one in 15 ... Investigation, their results identify small molecule drugs with ... neuronal injury in animal models of metabolic, chemical ...
Breaking Biology Technology: