Current state of purification,isolation and analysis of bacteriocins produced by lactic acid bacteria

Applied Microbiology and Biotechnology - The scientific interest for the search of natural means of microbial inhibitors has not faded for several years. A search of natural antibiotics, so-called...     

Prevalence,quantitative load and genetic diversity of <Emphasis Type="Italic">Campylobacter</Emphasis> spp. in dairy cattle herds in Lithuania

Background

Campylobacteriosis is a zoonotic disease, and animals such as poultry, pigs and cattle may act as reservoirs for Campylobacter spp. Cattle shed Campylobacter spp. into the environment and they can act as a reservoir for human infection directly via contact with cattle or their faeces or indirectly by consumption of contaminated food. The aim of this study was to determine the prevalence, the quantitative load and the genetic strain diversity of Campylobacter spp. in dairy cattle of different age groups.

Results

Faecal samples of 200 dairy cattle from three farms in the central part of Lithuania were collected and examined for Campylobacter. Cattle herds of all three farms were Campylobacter spp. positive, with a prevalence ranging from 75% (farm I), 77.5% (farm II) to 83.3% (farm III). Overall, the highest prevalence was detected in calves (86.5%) and heifers (86.2%). In contrast, the lowest Campylobacter prevalence was detectable in dairy cows (60.6%). C. jejuni, C. coli, C. lari and C. fetus subsp. fetus were identified in faecal samples of dairy cattle. C. upsaliensis was not detectable in any sample. The high counts of Campylobacter spp. were observed in faecal material of dairy cattle (average 4.5 log₁₀ cfu/g). The highest numbers of Campylobacter spp. were found in faecal samples from calves (average 5.3 log₁₀ cfu/g), whereas, faecal samples from cows harboured the lowest number of Campylobacter spp. (average 3.7 log₁₀ cfu/g). Genotyping by fla A PCR-RFLP analysis of selected C. jejuni isolates showed that some genotypes were present in all farms and all age groups. However, farm or age specific genotypes were also identified.

Conclusions

Future studies are needed to investigate risk factors related to the degree of colonisation in cattle. Based on that, possible measures to reduce the colonisation and subsequent shedding of Campylobacter in cattle could be established. It is important to further investigate the epidemiology of Campylobacter in the cattle population in order to assess associated risks to public health.

     

In Vivo Delivery of Gremlin siRNA Plasmid Reveals Therapeutic Potential against Diabetic Nephropathy by Recovering Bone Morphogenetic Protein-7

Diabetic nephropathy is a complex and poorly understood disease process, and our current treatment options are limited. It remains critical, then, to identify novel therapeutic targets. Recently, a developmental protein and one of the bone morphogenetic protein antagonists, Gremlin, has emerged as a novel modulator of diabetic nephropathy. The high expression and strong co-localization with transforming growth factor- β1 in diabetic kidneys suggests a role for Gremlin in the pathogenesis of diabetic nephropathy. We have constructed a gremlin siRNA plasmid and have examined the effect of Gremlin inhibition on the progression of diabetic nephropathy in a mouse model. CD-1 mice underwent uninephrectomy and STZ treatment prior to receiving weekly injections of the plasmid. Inhibition of Gremlin alleviated proteinuria and renal collagen IV accumulation 12 weeks after the STZ injection and inhibited renal cell proliferation and apoptosis. In vitro experiments, using mouse mesangial cells, revealed that the transfect ion of gremlin siRNA plasmid reversed high glucose induced abnormalities, such as increased cell proliferation and apoptosis and increased collagen IV production. The decreased matrix metalloprotease level was partially normalized by transfection with gremlin siRNA plasmid. Additionally, we observed recovery of bone morphogenetic protein-7 signaling activity, evidenced by increases in phosphorylated Smad 5 protein levels. We conclude that inhibition of Gremlin exerts beneficial effects on the diabetic kidney mainly through maintenance of BMP-7 activity and that Gremlin may serve as a novel therapeutic target in the management of diabetic nephropathy.     

Phenotypic and Genotypic Characterizations of Campylobacter jejuni Isolated from the Broiler Meat Production Process

A set of C. jejuni isolates of different origins and flaA-genotypes obtained throughout the broiler meat production chain was tested in this study for a possible correlation of their origin, phylogenetic relationship, and phenotypic properties. Interestingly, the results showed a correlation of the origin and the phylogenetic relationship between the C. jejuni isolates and their ability to form biofilm, but not in their ability to survive at -18, 5, 20, and 48?°C. Two strains, a broiler cloacae isolate and a broiler fillet isolate, were unable to develop biofilm, while most of the C. jejuni isolates originating from meat and surfaces of the slaughterhouse readily formed biofilms after both 24, 48, and 72?h. Interestingly, these biofilm-forming strains were closely related. Furthermore, two strains that were isolated after disinfection developed significantly more biofilms after 24?h of incubation than the remaining strains. A comparative genomic analysis using DNA microarrays showed that the gene contents of strains that efficiently formed biofilms were different from those that did not. The study suggests that biofilm formation might be a lineage specific property, allowing C. jejuni to both survive environmental stress at the slaughterhouse and to attach to the surface of meat.     

Social,political, and economic factors responsible for the reemergence of trichinellosis in Serbia: a case study

Over the past decade, eastern Europe has experienced a resurgence of trichinellosis. A recent outbreak in Serbia, Yugoslavia, from December 2001 to January 2002, involving 309 people, revealed many of the causes for this reemergence. Epidemiological investigations indicate that the immediate cause of the recent outbreak was the consumption of smoked sausages produced by a small slaughterhouse or meat processor. However, failure of in-house meat inspection procedures and quality assurance as well as oversight by official veterinary control were also responsible. Further analysis of this breakdown in the food safety net revealed additional general factors that have yielded a seriously deficient veterinary control system, and these are factors that are relevant to the problems experienced throughout eastern Europe and other regions. The recent civil war that led to the breakup of the former Federation of Yugoslavia resulted in severe economic and demographic changes, including high inflation and external economic sanctions. This led to (1) the loss of large numbers of experienced veterinary control officers and their replacement with inexperienced personnel, (2) a change in the swine industry with reduction in the number of large establishments with in-house inspection and replacement with more than 1,000 small abattoirs, too small to afford full-time in-house inspection, and (3) an increase in smallholder pig farming with reduced government oversight to ensure high standards in pig-rearing practices (infection risk management). The consequences of these events have been a 300% increase in Serbian pig infection and a concomittant large increase in human outbreaks. Before 1990, swine trichinellosis in Serbia was confined to 4 small districts, but today about one third of the Republic is considered endemic for trichinellosis. The reemergence of trichinellosis in Serbia illustrates the ability of this zoonosis to "leak" through a poorly maintained food safety barrier and the vulnerability of effective veterinary control to national and international events.     

Helminths of red foxes (Vulpes vulpes) and raccoon dogs (Nyctereutes procyonoides) in Lithuania

Red foxes and raccoon dogs are hosts for a wide range of parasites including important zoonotic helminths. The raccoon dog has recently invaded into Europe from the east. The contribution of this exotic species to the epidemiology of parasitic diseases, particularly parasitic zoonoses is unknown. The helminth fauna and the abundance of helminth infections were determined in 310 carcasses of hunted red foxes and 99 of raccoon dogs from Lithuania. Both species were highly infected with Alaria alata (94·8% and 96·5% respectively) and Trichinella spp. (46·6% and 29·3%). High and significantly different prevalences in foxes and raccoon dogs were found for Eucoleus aerophilus (97·1% and 30·2% respectively), Crenosoma vulpis (53·8% and 15·1%), Capillaria plica (93·3% and 11·3%), C. putorii (29·4% and 51·5%), Toxocara canis (40·5% and 17·6%) and Uncinaria stenocephala (76·9% and 98·8%). The prevalences of the rodent-transmitted cestodes Echinococcus multilocularis, Taenia polyacantha, T. crassiceps and Mesocestoides spp. were significantly higher in foxes than in raccoon dogs. The abundances of E. multilocularis, Mesocestoides, Taenia, C. plica and E. aerophilus were higher in foxes than those in raccoon dogs. A. alata, U. stenocephala, C. putorii and Echinostomatidae had higher abundances in raccoon dogs. The difference in prevalence and abundance of helminths in both animals may reflect differences in host ecology and susceptibility. The data are consistent with red foxes playing a more important role than raccoon dogs in the transmission of E. multilocularis in Lithuania.     

Tolerance to low temperatures of domestic and sylvatic Trichinella spp. in rat muscle tissue

The present study was designed to investigate the tolerance to low temperatures of 9 Trichinella isolates in rat muscle tissue. Nine groups of 24 rats were infected with encapsulated Trichinella spiralis, Trichinella nativa, Trichinella britovi, Trichinella murrelli, Trichinella T6, Trichinella nelsoni, and 3 nonencapsulated Trichinella pseudospiralis strains. Six rats from each of the groups were necropsied at 5, 10, 20, and 40 wk postinfection (wpi). Muscle tissues containing Trichinella larvae were exposed to temperatures of -18, -5, and 5 C for 1 or 4 wk, and afterward the reproductive capacity index (RCI) in mice was determined for the 9 individual Trichinella isolates. Only T. nativa muscle larvae were infective after freezing at a temperature of -18 C. At 5 wpi all encapsulated isolates, except for the tropical species T. nelsoni, remained infective after exposure to a temperature of -5 C for both 1 and 4 wk, whereas nonencapsulated T. pseudospiralis survived only 1 wk of exposure. All Trichinella spp. remained infective after exposure to a temperature of 5 C. Muscle larvae for all investigated species remained infective as long as they persisted in live rats during the experiment. Analysis of variance showed a significant effect of age on the temperature tolerance of encapsulated T. spiralis and nonencapsulated T. pseudospiralis. In addition, significant interaction between age of muscle larvae and length of exposure was found. In general Trichinella muscle larvae of medium age (10 and 20 wpi) tolerated freezing better than early and late stages of infection (5 and 40 wpi). This is the first study to demonstrate such a relationship between age of infection and temperature tolerance of Trichinella spp. muscle larvae.