Review: BIOFILM AS A MAJOR FACTOR IN CONTAMINATION OF MILK AND DAIRY PRODUCTS WITH THERMODURIC BACTERIA
Priit Elias, Epp Songisepp, Andre Veskioja, Kadi RammulBio-Competence Centre of Healthy Dairy Products, Kreutzwaldi 1, 51014 Tartu, Estonia.
The primary source of thermoduric bacteria for contamination of milk and dairy products is raw milk. Contamination sources of raw milk are the surface of udder, milking-, cooling- and storage equipments. Inadequate cleaning and storage of milking equipment may cause formation of biofilm on the surfaces which are in contact with milk.
Thermoduric bacteria are divided on the basis of their physiological characteristics from thermophilic, mesophilic and psychrophilic bacteria
Thermoduric bacteria in biofilm have favourable conditions for reproduction. Bacteria in biofilm are much more resistant to temperatures and chemicals used on cleaning of equipment.
Characteristics of bacteria cells, the cell-surface properties and the properties of fluid suspending bacteria influenced binding of bacteria in biofilm formed on the surface of the equipment.
Outgrowth of thermoduric bacteria and contamination of processed milk take place from biofilm formed on the surfaces of regeneration and cooling sections of pasteurizes and from biofilms formed on the surfaces of separators and buffer tanks, which were in contact with milk.
Thermoduric bacteria in raw milk undergo the necessary heat treatment and after it, reproducing in biofilms which formed on the surfaces of equipment, they can turn now to the product. Thermoduric bacteria have often negative impact quality of dairy products.
Keywords: biofilm, thermoduric bacteria, milk and dairy products.
Source: Agraarteadus 2017 (28) 1:5-12.
THE RELIABILITY OF COLORADO POTATO BEETLES (LEPTINOTARSA DECEMLINEATA SAY) POPULATION DENSITY PREDICTIONS BASED ON PHENOLOGICAL AND OVERWINTERING DATA
Külli Hiiesaar, Viacheslav Eremeev, Ingrid H. WilliamsEstonian University of Life Sciences, Institute of Agricultural and Environmental Sciences, Kreutzwaldi 5, Tartu 51014, Estonia.
On the basis of phenological observations and overwintering mortality data in 2015/2016 we tried to predict the population density of Colorado potato beetle (Leptinotarsa decemlineata Say) (CPB) for the following season. Because of the late and cool spring in 2015, the beetles started to emerge from the soil at the end of May and, because of the low temperatures, did not start to reproduce immediately. The first egg clutches did not appear until the end of June. The low density of larvae and beetles in mid-summer lead us to expect low damage for the whole season. However, very warm weather in August and September induced the beetles to lay eggs and the population density increased sharply. A lot of the summer beetles managed to terminate their development in time and to dig into the soil for overwintering. Consequently, we expected the beetles to be abundant the following spring. However, a short, snowless, very cold period in January when air temperature fell to –30 °C and soil temperature to –6.6 °C nullified this prediction as over 90% of overwintering beetles perished. In spring 2016, very few beetles were found on the field and the potato plants remained undamaged until the end of June. Then, due to south-east storms at the end of June, very large migrations occurred and, some weeks later, various development stages of CPB were very abundant in potato fields. Thus, none of our predictions came true. The main reason for this was our extremely unstable weather conditions during summer and the overwintering period and the unpredictable large migrations from southern regions.
Keywords: population density, prediction, phenology, overwintering, weather conditions.
Source: Agraarteadus 2017 (28) 1:13-18.
Short Communication: PGF2α AND PARENTERAL ADMINISTRATION OF CEFTIOFUR AS A TREATMENT OF POSTPARTUM UTERINE INFLAMMATIONS IN DAIRY COWS
Julia Jeremejeva, Toomas Orro, Kalle KaskEstonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, Kreutzwaldi 62, Tartu 51014, Estonia.
Present study was designed to get additional knowledge about treatment of postpartum (PP) clinical metritis (CM) and clinical endometritis (CE), using combination of systemic antibiotics with administration of prostaglandin F2α (PGF2α), to determine the optimal time of treatment, to study effect of this treatment on clinical, physiological and fertility parameters.
Late pregnant dairy cows with diagnosed CM and CE were divided to the experimental and positive control groups and negative control groups were composed of healthy cows. Measurements of body temperature, examination of general health status and vaginal discharge, bacteriological and cytological examinations, determination of plasma or milk progesterone, measuring of acute phase proteins and data of fertility parameters were used for evaluation of treatment success. Using of combination of systemic administrations of ceftiofur with two injections of PGF2α at intervals of 8 h was compared with using of combination of intramuscular administration of ceftiofur with flunixin. Treatment of CE using systemic administrations of ceftiofur with two injections of PGF2α with an interval of 8 h in the early PP (5–10 day after calving) was compared with treatment in the late PP (30–35 day PP). The findings of the present study indicate that treatment of CM and CE using flunixin in addition to parenteral antibiotic did not improve clinical cure, inflammatory parameters or elimination of bacteria from the uterus. Regardless of more severe inflammation that was detected in animals from the group treated by parenteral administration of antibiotic with PGF2α they showed the same fertility parameters as healthy animals. Results of this study suggests that treatment of CE in the early PP period, using systemic administration of ceftiofur with two injections of PGF2α at an interval of 8 h, could be more preferable to using the same treatment in the late PP.
Keywords: endometritis, metritis, treatment, postpartum, PGF2, ceftiofur.
Source: Agraarteadus 2017 (28) 1:19-24.
LISTERIA MONOCYTOGENES PREVALENCE IN READY-TO-EAT FOOD PRODUCTS
Mati Roasto1, Kadrin Meremäe1, Toomas Kramarenko2, Mihkel Mäesaar2, Maiu Kuningas21 Estonian University of Life Sciences, Institute of Veterinary Medicine and Animal Sciences, F.R. Kreutzwaldi 56/3, 51014 Tartu, Estonia
2 Estonian Veterinary and Food Laboratory Kreutzwaldi 30, Tartu 51006, Estonia.
RTE meat and fish products with a long shelf‑life are associated with the high risk of transmission of L. monocytogenes to human. Also, soft and semi-soft cheeses are in focus according to potential contamination with L. monocytogenes bacteria. The aim of the study was to give an overview about the prevalence of L. monocytogenes in ready-to-eat food products obtained at food business operator’s self-control and at official control level. It was found that the highest L. monocytogenes prevalence was in RTE fish products (11.6%), followed by fruit and vegetable based products (3.9%), mixed salads (2.2%), culinary products (2.0%), non‑categorized RTE food products (1.4%), RTE meat products (0.9%) and meals from retail outlets (0.7%). L. monocytogenes was not found in food intended for infants and for medical purposes, and in gravy products. Generally, the prevalence of L. monocytogenes was low, except among RTE fish products, especially salted fish and fish products, smoked fish and cold‑smoked fish products among which the prevalence of L. monocytogenes was 28.6%, 28.3% and 14.3%, respectively.
Keywords: Listeria monocytogenes, RTE food products, prevalence.
Source: Agraarteadus 2017 (28) 1:25-31.
ESTABLISHMENT OF IN VITRO PROPAGATION PROTOCOL OF GERBERA JAMESONII BOLUS EX HOOK F.: EXPLANT AND MEDIA SELECTION TO PLANTLET ACCLIMATIZATION
Budi Winarto1, Muhammad Prama Yufdy21 Indonesian Ornamental Crops Research Institute, Jln. Raya Ciherang, PO. Box 8, Sdl, Pacet
2 Indonesian Agency for Agriculture Research and -Cianjur 43253, West Java-Indonesia. Phone no: +6285318815574. Development,Jln. Ragunan No. 29, Pasar Minggu, Jakarta Selatan 12540, Indonesia.
Gerbera (Gerbera jamesonii Bolus ex Hook f.) is an important ornamental plant commodity with high economical value in Indonesia; however, development of the plant in larger scale commercially is constrained by the availability of qualified-planting materials. Conventional propagation is clearly not suitable to overcome the problem and therefore in vitro propagation protocol is importantly addressed. In vitro propagation protocol of G. jamesonii was successfully established in the study. Different explants (shoot tips, young leaves, petioles and petals) were selected and cultured on Murashige and Skoog (MS) basalt medium containing different plant growth regulators. Shoot tips and half-strength MS medium containing 1.5 mg l-1 thidiazuron (TDZ) and 0.25 mg l-1 N6-benzylaminopurine (BAP) were suitable explant and initiation medium for shoot formation with 75% explant regeneration and 5.5 shoots produced per explant. Shoots derived from selection stage were proliferated on half-strength MS medium supplemented with 0.25 mg l-1 BAP and resulting higher shoot regeneration up to 7.5 shoots produced per shoot with 22.8 leaves and 0.83 cm leaf length. Multiplication of shoots on the half-strength MS medium fortified by 0.25 mg l-1 BAP increased gradually from the first subculture till the fifth subculture with 9.1 shoots produced per shoot subcultured and reduced thereafter. Shoots were then rooted on half-strength MS medium augmented with 0.5 mg l-1 α-naphthalene acetic acid (NAA) and 1.5 g l-1activated charcoal (AC) and produced 2.1 roots per shoot with 2.52 cm length of roots. Well-rooted shoots were acclimatized in a mixture of burned-rice husk and organic manure (1:1, v/v) with 95% survival rate and 114 plantlets grew well under this treatment.
Keywords: explant, basalt medium, plantlet, propagation, shoot, Gerbera jamesonii.
Source: Agraarteadus 2017 (28) 1:32-40.