Sharpea and Kandleria are lactic acid producing rumen bacteria that do not change their fermentation products when co-cultured with a methanogen

peer-reviewedSharpea and Kandleria are associated with rumen samples from low-methane-emitting sheep. Four strains of each genus were studied in culture, and the genomes of nine strains were analysed, to understand the physiology of these bacteria. All eight cultures grew equally well with d-glucose, d-fructose, d-galactose, cellobiose, and sucrose supplementation. d-Lactate was the major end product, with small amounts of the mixed acid fermentation products formate, acetate and ethanol. Genes encoding the enzymes necessary for this fermentation pattern were found in the genomes of four strains of Sharpea and five of Kandleria. Strains of Sharpea produced traces of hydrogen gas in pure culture, but strains of Kandleria did not. This was consistent with finding that Sharpea, but not Kandleria, genomes contained genes coding for hydrogenases. It was speculated that, in co-culture with a methanogen, Sharpea and Kandleria might change their fermentation pattern from a predominately homolactic to a predominately mixed acid fermentation, which would result in a decrease in lactate production and an increase in formation of acetate and perhaps ethanol. However, Sharpea and Kandleria did not change their fermentation products when co-cultured with Methanobrevibacter olleyae, a methanogen that can use both hydrogen and formate, and lactate remained the major end product. The results of this study therefore support a hypothesis that explains the link between lower methane yields and larger populations of Sharpea and Kandleria in the rumens of sheep

Cultivation and sequencing of rumen microbiome members from the Hungate1000 Collection

Productivity of ruminant livestock depends on the rumen microbiota, which ferment indigestible plant polysaccharides into nutrients used for growth. Understanding the functions carried out by the rumen microbiota is important for reducing greenhouse gas production by ruminants and for developing biofuels from lignocellulose. We present 410 cultured bacteria and archaea, together with their reference genomes, representing every cultivated rumen-associated archaeal and bacterial family. We evaluate polysaccharide degradation, short-chain fatty acid production and methanogenesis pathways, and assign specific taxa to functions. A total of 336 organisms were present in available rumen metagenomic data sets, and 134 were present in human gut microbiome data sets. Comparison with the human microbiome revealed rumen-specific enrichment for genes encoding de novo synthesis of vitamin B12, ongoing evolution by gene loss and potential vertical inheritance of the rumen microbiome based on underrepresentation of markers of environmental stress. We estimate that our Hungate genome resource represents ?75% of the genus-level bacterial and archaeal taxa present in the rumen.publishersversionPeer reviewe

Enzymes produced by bacteria within biofilms of dairy origin and their effect on dairy products : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy, Massey University, Palmerston North, New Zealand

Content published as: Teh, K.H., Flint, S., Palmer, J., Lindsay, D., Andrewes, P., & Bremer, P. (2011). Thermo-resistant enzyme-producing bacteria isolated from the internal surfaces of raw milk tankers. International Dairy Journal, 21(10), 742-747. doi: 10.1016/j.idairyj.2011.04.013. .(chapter 3b). Teh, K.H., Flint, S., Palmer, J., Andrewes, P., Bremer, P. & Lindsay, D. (2012). Proteolysis produced within biofilms of bacterial isolates from raw milk tankers. International Journal of Food Microbiology, 157, 28-34. doi: 10.1016/j.ijfoodmicro.2012.04.008. (chapter 4a). Teh, K.H., Lindsay, D., Palmer, J., Andrewes, P., Bremer, P., & Flint, S. (2013). Lipolysis within single culture and co-culture biofilms of dairy origin. International Journal of Food Microbiology, 163(2-3), 129-135. doi: 10.1016/j.ijfoodmicro.2013.02.009. (chapter 4b)Prior to the current study, there was no scientific evidence that enzymes produced by bacteria within biofilms in milk transport tanker could have a detrimental effect on the quality of dairy products. Bacteria attached to the internal surfaces of milk tankers were isolated, identified, and characterized in terms of their ability to produce heat-stable enzymes (protease and lipase) and to form biofilms. Twelve of the bacterial isolates were identified by 16s DNA sequencing as belonging to the genera Bacillus, Staphylococcus, Streptococcus, Pseudomonas, and Serratia. Six of the dairy bacterial isolates were evaluated for their ability to produce proteolysis in milk when growing within either single culture or co-culture biofilms in an in vitro model system that simulated the upper part of a milk tanker during a typical summer’s day of milk collection in New Zealand. Proteolysis per cfu decreased as the temperature of incubation increased (20-37 °C), and proteolysis per cfu was generally higher within biofilms compared with the corresponding planktonic cultures. Lipolysis by bacteria within biofilms in the in vitro model was investigated using single or co-culture biofilms or planktonic cultures of four dairy bacteria and a known lipase-producing bacterium. The hydrolysis of p-nitrophenol palmitate was at least 10 times higher by bacteria within biofilms (0.01 to 8.35 nU/CFU) than in planktonic cultures (0.01 to 0.07 nU/CFU). The effect of proteases on UHT skim milk was determined by exposing sterile skim milk to a multispecies biofilm formed on an in vitro model of a milk tanker. The amount of free peptides which indicated proteolysis in the UHT milk was monitored over five months of storage. Free peptides were higher in UHT milk that had been made from milk exposed to the multispecies biofilm, than in UHT milk that had been made from milk that had not been exposed to the biofilm. Enzymes that are secreted from biofilms into raw milk during transportation can potentially reduce the quality of dairy products. Improvements at this early stage of dairy manufacture may reduce economic loss in the dairy industry

Biofilm formation by Campylobacter jejuni in controlled mixed-microbial populations : a thesis presented in partial fulfillment of the requirements for the degree of Master of Technology in Food Technology at Massey University, Palmerston North, New Zealand

Poultry meat consumption in New Zealand has been increasing since 1975 with the highest peak reported in 2006. The total poultry meat consumption was 36.5 kg per capita in the year ending September 2006. Consumption of contaminated food with raw poultry can lead to campylobacteriosis, which is a food-borne disease that causes gastroenteritis in humans and it is a major problem in New Zealand. There were 12,776 reported cases of campylobacteriosis in 2007, which accounts for 65.9% of the overall notified diseases. Campylobacteriosis can lead to Guillain-Barré syndrome in some patients, an autoimmune disorder of the peripheral nervous system. Campylobacteriosis is caused by consumption of either Campylobacter jejuni or Campylobacter coli. Campylobacter spp. have been found in commercially raised poultry being infected predominantly by C. jejuni. C. jejuni has been found associated with biofilms of other bacterial species in the watering supplies and plumbing systems of animal husbandry facilities and animalprocessing plants. A biofilm is an assemblage of microbial cells that is associated with a surface and the cells are enclosed in a matrix of polysaccharides, which provides a survival advantage to the bacteria in the film. In this study, the ability to form biofilm was measured in a laboratory assay using microtitre plates. C. jejuni strains in monoculture were shown to attach to the abiotic surface and form biofilms to various degrees, thus potentially enhancing their survivability in the poultry environment. C. jejuni was also shown to have the ability to attach and survive in mixed-microbial populations. Biofilm formation may play a role in the epidemiology of C. jejuni infections. Enterococcus faecalis and Staphylococcus simulans may play a role in the biofilm formation in the poultry environment as both of these microorganisms were able to form, and harbour C. jejuni in their biofilms. Pseudomonas aeruginosa seemed to inhibit biofilm formation and C. jejuni in the mixed-microbial population. Further studies are required to establish control measures against the formation of biofilms containing C. jejuni in poultry processing plants and farms in New Zealand to reduce the reservoir of contamination and thus reduce the incidence of campylobacteriosis

Acute Supplementation with Nitrate-Rich Beetroot Juice Causes a Greater Increase in Plasma Nitrite and Reduction in Blood Pressure of Older Compared to Younger Adults

Nitrate-rich beetroot juice supplementation has been shown to improve cardiovascular and cognitive function in younger and older adults via increased nitric oxide production. However, it is unclear whether the level of effects differs between the two groups. We hypothesized that acute supplementation with nitrate-rich beetroot juice would improve cardiovascular and cognitive function in older and younger adults, with the potential for greater improvements in older adults. Thirteen younger (18–30 years) and 11 older (50–70 years) adults consumed either 150 mL of nitrate-rich beetroot juice (BR; 10.5 mmol nitrate) or placebo (PL; 1 mmol nitrate) in a double-blind, crossover design, 2.25 h prior to a 30-min treadmill walk. Plasma nitrate and nitrite concentrations, blood pressure (BP), heart rate (HR), cognitive function, mood and perceptual tests were performed throughout the trial. BR consumption significantly increased plasma nitrate (p < 0.001) and nitrite (p = 0.003) concentrations and reduced systolic BP (p < 0.001) in both age groups and reduced diastolic BP (p = 0.013) in older adults. Older adults showed a greater elevation in plasma nitrite (p = 0.038) and a greater reduction in diastolic BP (p = 0.005) following BR consumption than younger adults. Reaction time was improved in the Stroop test following BR supplementation for both groups (p = 0.045). Acute BR supplementation increased plasma nitrite concentrations and reduced diastolic BP to a greater degree in older adults; whilst systolic BP was reduced in both older and younger adults, suggesting nitrate-rich BR may improve cardiovascular health, particularly in older adults due to the greater benefits from reductions in diastolic BP

Does Acute Supplementation with Nitrate-Rich Beetroot Juice Benefit Older Adults More than Younger Adults

Background: To investigate age-related effects of acute dietary nitrate (NO3−) supplementationon cardiovascular responses, cognition and mood. [...

Bacterial fouling in dairy processing

Bacterial contamination in dairy manufacture is a problem that can affect product quality, the economic viability of dairy product manufacture and the sustainability of the industry. Bacterial fouling of surfaces, termed biofilms, occurs at all stages of dairy product manufacture from raw milk collection through to waste treatment. Biofilms are considered a major source of contamination of products through the release of microorganisms and enzymes into dairy products. Recognition of the importance of biofilm issues in the dairy industry is reflected in the growth in publications on this topic. We still, however, have a limited understanding of the role that the different components of the biofilm matrix play in a dairy environment in facilitating cell attachment, growth and persistence. Of particular interest is the residual biochemical material left behind once much of the biofilm has been removed and the role it has in the development of subsequent biofilm

Genomic analysis of three Bifidobacterium species isolated from the calf gastrointestinal tract.

Ruminant animals contribute significantly to the global value of agriculture and rely on a complex microbial community for efficient digestion. However, little is known of how this microbial-host relationship develops and is maintained. To begin to address this, we have determined the ability of three Bifidobacterium species isolated from the faeces of newborn calves to grow on carbohydrates typical of a newborn ruminant diet. Genome sequences have been determined for these bacteria with analysis of the genomes providing insights into the host association and identification of several genes that may mediate interactions with the ruminant gastrointestinal tract. The present study provides a starting point from which we can define the role of potential beneficial microbes in the nutrition of young ruminants and begin to influence the interactions between the microbiota and the host. The differences observed in genomic content hint at niche partitioning among the bifidobacterial species analysed and the different strategies they employ to successfully adapt to this habitat