SUMMARY: An improved growth medium for lactobacilli is described. It supports good growth of lactobacilli generally and also is particularly useful for a number of fastidious strains which grow only poorly in other general media. In addition, tomato juice, a highly variable material, is not required. In a slightly modified form, it can also be used as a basal medium for fermentation tests.

Changing the diet of five lactating cows and one nonlactating cow from high to low roughage induced milk fat depression in the lactating cows and altered the composition of the rumen microflora. While the numbers of lactic and propionic acid-producing bacteria increased, the numbers of Butyrivibrio spp. decreased. The numbers of lipolytic bacteria and the in vitro lipolytic activity of the rumen fluid were also decreased, as was the extent of hydrogenation of linoleic and linolenic acids combined in soybean oil incubated in vitro with rumen fluid. It is suggested that among the bacterial population in the rumen the vibrios, which were adversely affected by the low-roughage diets, may contribute significantly to both lipolysis and hydrogenation in the rumen.

SummaryThe highest incidence of lipolytic activity among the psychrotrophic Gram-negative flora of commercial raw milks was found in strains ofPseudomonas fluorescensandPs. fragi.The lipases of all of the lipolytic strains remained wholly or partly active after heat treatment at 63°C for 30 min. Two of the strains tested further had lipases which retained 20–25% of their activity even when heated at 100 °C for 10 min. Cheeses made from milks in which strains or a single strain of lipolytic Gram-negative rods (GNR) had been allowed to multiply to > 107colony forming units/ml became rancid after 4 months even though the GNR had been killed by pasteurization. The rancidity was characterized by a soapy off-flavour in cheeses containing free fatty acid concentrations from 3 to 10 times higher than those in control cheeses made from stored milks with low counts of GNR. Strong rancidity could be reproduced by adding the culture supernatant of a pre-grown lipolytic strain, but not the washed cells, to milk and pasteurizing it immediately before cheese-making, demonstrating the extracellular nature of the rancidity-inducing lipases.

Summary. The rumen microbial population associated with feeding cows 3 rations, hay alone, 20% hay/80% flaked maize and 20% hay/80% rolled barley has been examined. The differences between the hay and the cereal rations were considerable but between the cereal rations only slight. Both cereal rations provoked & large drop in the proportion of butyrivibrios, and a rise in the proportion of selenomonads, peptostreptococci, lactobacilli and bifidobacteria. The importance of these and other changes occurring in the microbial flora are discussed in relation to their possible effect on the products of the rumen fermentation.

The designation ' Doderlein's bacillus ' for human vaginal strains of the genus LactobaciUzcar is vague and unsatisfactory, Thirty-five strains of lactobacilli from twenty-one normal non-pregnant women aged 21-80 were isolated; c. 25% were heterofermentative. Of 21 isolates studied in detail, 18 were L. acidophilw and two were L. cmei var. rhnosecs (Rogosa et al. 1958). The heterofermentative species comprised four strains of L. f m t i and one of L. cellobiom (Rogosa et aZ. 1938). Glycogen fermentation, which was found only in certain strains of L. acidophilus, was a variable characteristic. In addition, Leuconostoc mesentmoides, which on examination of smears can be confused with short rod forms, was also isolated.

Two New Species of Lactobacillus Isolated from the Bovine Rumen,Lactobacillus ruminis sp.nov. and Lactobacillus vitulinus sp.nov. Two new anaerobic species of Lac-tobacillirs from the bovine rumen are described. They belong to the subgenus Tliermobacteriunz and contain nieso diaminopimelic acid in the wall peptidoglycan. The species differ from each other in being motile and non-motile, in the type of lactic acid produced and in : / $ base composition of their DNA. They have been named Lacrobacillus rumhis and L. i*iti/lims.

The gelation of ultra-high-temperature (UHT) sterilized milk is one of the factors which limits its shelf life (Burton, 1969; Hostettler, 1972), but it is not clear to what extent chemical changes or the action of proteolytic enzymes are involved. Samel, Weaver & Gammack (1971) reported that the extent of proteolysis in long-term stored UHT milk was unrelated to the onset of gelation, but Corradini (1975) showed that gelation of UHT milk was accompanied by K-casein breakdown and suggested that this was analogous to enzymic coagulation by rennet. Adams, Barach & Speck (1975) and Driessen (1976) reported that added heat resistant Pseudomonas proteases caused rapid spoiling (by clearing or coagulation) of sterile milk. The widespread practice of storing cooled raw bulk milk for extended periods before processing has increased the probability that psychrotrophic bacteria will grow and produce heat resistant enzymes (Law, Sharpe & Chapman, 1976) capable of causing spoilage of stored dairy products; the present paper reports the gelation of UHT milk by a /c-casein-degrading enzyme produced during the growth of a psychrotrophic strain of Pseudomonas fluorescens previously isolated from raw milk.

BackgroundInfectious bronchitis virus (IBV) is a pathogenic chicken coronavirus. Currently, vaccination against IBV is only partially protective; therefore, better preventions and treatments are needed. Plants produce antimicrobial secondary compounds, which may be a source for novel anti-viral drugs. Non-cytotoxic, crude ethanol extracts of Rhodiola rosea roots, Nigella sativa seeds, and Sambucus nigra fruit were tested for anti-IBV activity, since these safe, widely used plant tissues contain polyphenol derivatives that inhibit other viruses.ResultsDose–response cytotoxicity curves on Vero cells using trypan blue staining determined the highest non-cytotoxic concentrations of each plant extract. To screen for IBV inhibition, cells and virus were pretreated with extracts, followed by infection in the presence of extract. Viral cytopathic effect was assessed visually following an additional 24 h incubation with extract. Cells and supernatants were harvested separately and virus titers were quantified by plaque assay. Variations of this screening protocol determined the effects of a number of shortened S. nigra extract treatments. Finally, S. nigra extract-treated virions were visualized by transmission electron microscopy with negative staining.Virus titers from infected cells treated with R. rosea and N. sativa extracts were not substantially different from infected cells treated with solvent alone. However, treatment with S. nigra extracts reduced virus titers by four orders of magnitude at a multiplicity of infection (MOI) of 1 in a dose-responsive manner. Infection at a low MOI reduced viral titers by six orders of magnitude and pretreatment of virus was necessary, but not sufficient, for full virus inhibition. Electron microscopy of virions treated with S. nigra extract showed compromised envelopes and the presence of membrane vesicles, which suggested a mechanism of action.ConclusionsThese results demonstrate that S. nigra extract can inhibit IBV at an early point in infection, probably by rendering the virus non-infectious. They also suggest that future studies using S. nigra extract to treat or prevent IBV or other coronaviruses are warranted.