ABSTRACT
AIMS: The microbial quality of farm bulk-tank raw milk produced in Estonia during years 2004-2007 was investigated. METHODS AND RESULTS: Bulk-tank milk samples were analysed for lactic acid bacteria count (LABC), psychrotrophic bacteria count (PBC), aerobic spore-forming bacteria count (ASFBC), total bacterial counts using BactoScan and somatic cell count (SCC) using Fossomatic. Randomly selected psychrotrophic isolates were subjected to 16S-23S PCR-ribotyping. LABC remained below 10(4) CFU ml(-1) in most samples, while psychrotrophic micro-organisms dominated in 60% of farms. PBC ranged from 4.2 × 10(2) to 6.4 × 10(4) CFU ml(-1), and ASFBC varied from 5 to 836 CFU ml(-1). CONCLUSIONS: In general, the microbiological quality of the farm bulk-tank milk was good - more than 91% of samples contained <50,000 CFU ml(-1), and SCC in the majority of samples did not exceed the internationally recommended limits. Genus Pseudomonas spp. was the dominating spoilage flora with Pseudomonas fluorescens as the prevailing species. SIGNIFICANCE AND IMPACT OF THE STUDY: Specific bacterial groups (LABC, PBC and ASFBC), not analysed routinely by dairies, were determined in bulk-tank raw milk of numerous dairy farms during 4-year period. Based on the survey, dairy plants can better control their supply chains and select farms (milk) for the production of specific products, i.e. milk with low PBC and high LABC for cheesemaking.
Subject(s)
Bacteria/isolation & purification , Food Microbiology , Milk/microbiology , Animals , Bacteria/classification , Bacterial Load , Estonia , Food Contamination , Pseudomonas fluorescens/classification , Pseudomonas fluorescens/isolation & purification , RibotypingABSTRACT
Lactobacillus plantarum was grown in complex media containing glucose and yeast extract. The maximum growth yield based on yeast extract consumption was 0.5 g dwt g-1. Growth yield YATP 15-17 g dwt mol ATP-1 was almost constant in the glucose limited A-stat experiment whereas in the yeast extract limited culture it increased with dilution rate. The maximum specific growth rate observed, 0.5 h-1, was similar for both A-stat and batch cultures. Specific oxygen consumption, QO2, reached the value of 1.8 mmol O2 h-1 g dwt-1. It was shown that Val, Ile, Leu, Tyr and Phe, were consumed mainly as free amino acids, while Asp, Pro, Lys and Arg were derived from peptides. Significantly more Asp, Ser, Glu, Val, Ile, Leu and Phe were consumed than needed to build up cell protein whereas some Pro, Gly, Ala and Lys was synthesized. A network of metabolic reactions in L. plantarum was proposed on the basis of the experimental data.
Subject(s)
Lactobacillus/physiology , Amino Acids/metabolism , Bacteriological Techniques , Culture Media , Lactobacillus/growth & development , Lactobacillus/metabolismABSTRACT
The authors describe the history of enzootic bovine leukosis (EBL) in Estonia, including the occurrence and distribution of disease within the cattle population, and the factors which have influenced disease spread since the 1950s. The principles of various control schemes which were applied from 1960 to 1994 are also surveyed. Considerable progress in eradicating EBL has been achieved during recent years, as a result of systematic serological herd testing, and the slaughter of cattle infected with bovine leukaemia virus (BLV). The decrease in the numbers of EBL-affected cattle may be expressed by the reduction in the number of leukotic tumour cases recorded annually: from an average of 180 cases per 100,000 cows in the 1980s to four cases in 1994; and by the decrease in the average prevalence of BLV-infected animals in the cattle population, from 31.4% in 1989 to 0% in 1994. The national EBL control programme will be continued. It is hoped that Estonia can be declared EBL-free within the coming years.
