Direct in situ viability assessment of bacteria in probiotic dairy products using viability staining in conjunction with confocal scanning laser microscopy.

نویسندگان

  • M A Auty
  • G E Gardiner
  • S J McBrearty
  • E O O'Sullivan
  • D M Mulvihill
  • J K Collins
  • G F Fitzgerald
  • C Stanton
  • R P Ross
چکیده

The viability of the human probiotic strains Lactobacillus paracasei NFBC 338 and Bifidobacterium sp. strain UCC 35612 in reconstituted skim milk was assessed by confocal scanning laser microscopy using the LIVE/DEAD BacLight viability stain. The technique was rapid (<30 min) and clearly differentiated live from heat-killed bacteria. The microscopic enumeration of various proportions of viable to heat-killed bacteria was then compared with conventional plating on nutrient agar. Direct microscopic enumeration of bacteria indicated that plate counting led to an underestimation of bacterial numbers, which was most likely related to clumping. Similarly, LIVE/DEAD BacLight staining yielded bacterial counts that were higher than cell numbers obtained by plate counting (CFU) in milk and fermented milk. These results indicate the value of the microscopic approach for rapid viability testing of such probiotic products. In contrast, the numbers obtained by direct microscopic counting for Cheddar cheese and spray-dried probiotic milk powder were lower than those obtained by plate counting. These results highlight the limitations of LIVE/DEAD BacLight staining and the need to optimize the technique for different strain-product combinations. The minimum detection limit for in situ viability staining in conjunction with confocal scanning laser microscopy enumeration was approximately 10(8) bacteria/ml (equivalent to approximately 10(7) CFU/ml), based on Bifidobacterium sp. strain UCC 35612 counts in maximum-recovery diluent.

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Bacterial localization and viability assessment in human ex vivo dentinal tubules by fluorescence confocal laser scanning microscopy.

AIM To develop a convenient method for the localization and quantification of live and dead bacteria in human ex vivo mineralized dentinal tubules. METHODOLOGY The roots from human single-rooted teeth (n = 12) were infected with Enterococcus faecalis V583 and either treated with calcium hydroxide paste or left untreated; six control roots were uninoculated and untreated. Following further inc...

متن کامل

Viability of Probiotic Bacteria in Yogurts Produced in Mazandaran Province Exposed to Simulated Gastrointestinal Conditions

 Background and purpose: Production of functional foods is one of the most important achievements in food industry and using these products provides the convergence of two important events in life; namely receiving nutrients from the diet and promoting health for consumers at the same time. This study aimed to verify the viability of microorganisms and stability of these microorganisms in diges...

متن کامل

Real-time assessment of corneal endothelial cell damage following graft preparation and donor insertion for DMEK

PURPOSE To establish a method for assessing graft viability, in-vivo, following corneal transplantation. METHODS Optimization of calcein AM fluorescence and toxicity assessment was performed in cultured human corneal endothelial cells and ex-vivo corneal tissue. Descemet membrane endothelial keratoplasty grafts were incubated with calcein AM and imaged pre and post preparation, and in-situ af...

متن کامل

Bacterial plasmolysis as a physical indicator of viability.

Bacterial plasmolytic response to osmotic stress was evaluated as a physical indicator of membrane integrity and hence cellular viability. Digital image analysis and either low-magnification dark-field, high-magnification phase-contrast, or confocal laser microscopy, in conjunction with pulse application of a 1.5 M NaCl solution, were used as a rapid, growth-independent method for quantifying t...

متن کامل

Production of Cereal- based Probiotic Beverage Optimized by Response Surface Methodology and Investigation of Its Properties

Background and Objectives: In general, most probiotic products are dairy-based and a few efforts have been made to develop probiotic products using other substrates such as cereal grains. Rice can be used as a basis for the production of many functional foods. However, rice in Iran is mostly consumed as plate food rather than in the formulation of relevant functional foods. In this study, the r...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

برای دانلود متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

عنوان ژورنال:
  • Applied and environmental microbiology

دوره 67 1  شماره 

صفحات  -

تاریخ انتشار 2001