Spontaneous fermentation of traditional sago starch in Papua New Guinea

Sago starch is an important dietary carbohydrate in lowland Papua New Guinea (PNG). An investigation was conducted to determine whether microbes play a role in its preservation using traditional methods. In 12 stored sago samples collected from PNG villages, lactic acid bacteria (LAB) were present (>= 3.6 x 10(4) cfu/g) and pH ranged from 6.8 to 4.2. Acetic and propionic acids were detected in all samples, while butyric, lactic and valeric acids were present in six or more. In freshly prepared sago, held in sealed containers in the laboratory at 30 degrees C, spontaneous fermentation by endogenous microflora of sago starch was observed. This was evident by increasing concentrations of acetic, butyric and lactic acids over 4 weeks, and pH reducing from 4.9 to 3.1: both LAB and yeasts were involved. Survival of potential bacterial pathogens was monitored by seeding sago starch with similar to 10(4)/g of selected organisms. Numbers of Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus fell to <30/g within 7 days. Salmonella sp. was present only in low numbers after 7 days (<36/g), but Escherichia coli was still detectable after three weeks (>10(2)/g). Fermentation appeared to increase the storability and safety of the product.

Coliforms in processed mango: Significance and control

The aims of this investigation were to enumerate coliforms in fresh mangoes, puree, cheeks, and cheeks-in-puree in order to determine the source of these organisms in the processed products, to determine methods for their control, and to identify coliforms isolated from cheeks-in-puree to determine whether they have any public health significance. Product from four processors was tested on two occasions. The retail packs of cheeks-in-puree having the highest coliform counts were those in which raw puree was added to the cheeks. Coliform counts in these samples ranged between 1.4 × 103 and 5.4 × 104 cfu/g. Pasteurisation reduced the coliform count of raw puree to < 5 cfu/g. Forty-seven percent of the 73 colonies, isolated as coliforms on the basis of their colony morphology on violet red bile agar, were identified as Klebsiella pneumoniae using the ATB 32E Identification System. Klebsiella strains were tested for growth at 10 °C, faecal coliform response, and fermentation of -melizitose, to differentiate the three phenotypically similar strains, K. pneumoniae, K. terrigena and K planticola. Results indicated that 41% of K. pneumoniae isolates gave reactions typical of K. pneumoniae. A further 44% of strains gave an atypical reaction pattern for these tests and were designated ‘psychrotrophic’ K. pneumoniae. Klebsiella pneumoniae counts of between 2.1 × 103 and 4.9 × 104 cfu/g were predicted to occur in the retail packs of mango cheeks-in-puree produced by the processors who constituted this product with raw puree. In view of the opportunistic pathogenic nature of K. pneumoniae, its presence in these products is considered undesirable and steps, such as pasteurisation of puree, should be taken in order to inactivate it

Predicting survival of western rock lobsters Panulirus cygnus using discriminant analysis of hemolymph parameters taken immediately following simulated handling treatments

Instances of morbidity amongst rock lobsters (Panulirus cygnus) arriving at factories in Western Australia (WA) have been attributed to stress during post-harvest handling. This study used discriminant analysis to determine whether physiological correlates of stress following a period of simulated post-harvest handling had any validity as predictors of future rejection or morbidity of western rock lobsters. Groups of 230 western rock lobsters were stored for 6 h in five environments (submerged/flowing sea water, submerged/re-circulating sea water, humid air, flowing sea water spray, and re-circulated sea water spray). The experiment was conducted in late spring (ambient sea water 22°C), and repeated again in early autumn (ambient sea water 26°C). After 6 h treatment, each lobster was graded for acceptability for live export, numbered, and its hemolymph was sampled. The samples were analysed for a number of physiological and health status parameters. The lobsters were then stored for a week in tanks in the live lobster factory to record mortality. The mortality of lobsters in the factory was associated with earlier deviations in hemolymph parameters as they emerged from the storage treatments. Discriminant analysis (DA) of the hemolymph assays enabled the fate of 80-90% of the lobsters to be correctly categorised within each experiment. However, functions derived from one experiment were less accurate at predicting mortality when applied to the other experiments. One of the reasons for this was the higher mortality and the more severe patho-physiological changes observed in lobsters stored in humid air or sprays at the higher temperature. The analysis identified lactate accumulation during emersion and associated physiological and hemocyte-related effects as a major correlate of mortality. Reducing these deviations, for example by submerged transport, is expected to ensure high levels of survival. None of the indicators tested predicted mortality with total accuracy. The simplest and most accurate means of comparing emersed treatments was to count the mortality afterwards.

Near infrared spectroscopy as a rapid tool to measure volatile aroma compounds in Riesling wine: Possibilities and limits

Volatile chemical compounds responsible for the aroma of wine are derived from a number of different biochemical and chemical pathways. These chemical compounds are formed during grape berry metabolism, crushing of the berries, fermentation processes (i.e. yeast and malolactic bacteria) and also from the ageing and storage of wine. Not surprisingly, there are a large number of chemical classes of compounds found in wine which are present at varying concentrations (ng L-1 to mg L-1), exhibit differing potencies, and have a broad range of volatilities and boiling points. The aim of this work was to investigate the potential use of near infrared (NIR) spectroscopy combined with chemometrics as a rapid and low-cost technique to measure volatile compounds in Riesling wines. Samples of commercial Riesling wine were analyzed using an NIR instrument and volatile compounds by gas chromatography (GC) coupled with selected ion monitoring mass spectrometry. Correlation between the NIR and GC data were developed using partial least-squares (PLS) regression with full cross validation (leave one out). Coefficients of determination in cross validation (R 2) and the standard error in cross validation (SECV) were 0.74 (SECV: 313.6 μg L−1) for esters, 0.90 (SECV: 20.9 μg L−1) for monoterpenes and 0.80 (SECV: 1658 ?g L-1) for short-chain fatty acids. This study has shown that volatile chemical compounds present in wine can be measured by NIR spectroscopy. Further development with larger data sets will be required to test the predictive ability of the NIR calibration models developed.

Diversity of methanogens in ruminants in Queensland

Methane emissions from ruminant livestock represent a loss of carbon during feed conversion, which has implications for both animal productivity and the environment because this gas is considered to be one of the more potent forms of greenhouses gases contributing to global warming. Many strategies to reduce emissions are targeting the methanogens that inhabit the rumen, but such an approach can only be successful if it targets all the major groups of ruminant methanogens. Therefore, a thorough knowledge of the diversity of these microbes in different breeds of cattle and sheep, as well as in response to different diets, is required. A study was undertaken using the molecular techniques denaturing gradient gel electrophoresis, DNA cloning and DNA sequence analysis to define the extent of diversity among methanogens in ruminants, particularly Bos indicus cross cattle, on differing forages in Queensland. It was found that the diversity of methanogens in forage-fed cattle in Queensland was greater than in grain-fed cattle but there was little variability in methanogen community composition between cattle fed different forages. The species that dominate the rumen microbial communities of B. indicus cross cattle are from the genus Methanobrevibacter, although rumen-fluid inoculated digestors fed Leucaena leucocephala leaf were populated with Methanosphaera-like strains, with the Methanobrevibacter-like strains displaced. If ruminant methane emissions are to be reduced, then antimethanogen bioactives that target both broad groups of ruminant methanogens are most likely to be needed, and as a part of an integrated suite of approaches that redirect rumen fermentation towards other more useful end products.

Hydrogen utilising bacteria from the forestomach of eastern grey (Macropus giganteus) and red (Macropus rufus) kangaroos

Reductive acetogenesis is an alternative to methanogenesis for removing hydrogen produced during enteric fermentation. In Australia, kangaroos have evolved an enlarged forestomach analogous to the rumen of sheep and cattle. However, unlike sheep and cattle, kangaroos produce very little methane from enteric fermentation. From samples of gut contents from five eastern grey and three red kangaroos, we were not able to detect methanogens using a PCR protocol, but did detect the formyltetrahydrofolate synthetase (FTHFS) gene (likely to be used for reductive acetogenesis) in all animals. Isolations to recover acetogens resulted in two different classes of hydrogen consuming bacteria being isolated. The first class consisted of acetogens that possessed the FTHFS gene, which except for Clostridium glycolicum, were not closely related to any previously cultured bacteria. The second class were not acetogens but consisted of enterobacteria (Escherichia coli and Shigella) that did not possess FTHFS genes but did utilise hydrogen and produce acetate. Enumeration of the acetogens containing the FTHFS gene by real-time PCR indicated that bacteria of the taxa designated YE257 were common to all the kangaroos whereas YE266/YE273 were only detected in eastern grey kangaroos. When present, both species occurred at densities above *106 cell equivalents per mL. C. glycolicum was not detected in the kangaroos and, unlike YE257 and YE266/273, is unlikely to play a major role in reductive acetogenesis in the foregut of kangaroos.

An improved technique for estimating short-term survival of released line-caught fish, and an application comparing barotrauma-relief methods in red emperor (Lutjanus sebae Cuvier 1816).

Promotion of better procedures for releasing undersize fish, advocacy of catch-and-release angling, and changing minimum legal sizes are increasingly being used as tools for sustainable management of fish stocks. However without knowing the proportion of released fish that survive, the conservation value of any of these measures is uncertain. We developed a floating vertical enclosure to estimate short-term survival of released line-caught tropical and subtropical reef-associated species, and used it to compare the effectiveness of two barotrauma-relief procedures (venting and shotline releasing) on red emperor (Lutjanus sebae). Barotrauma signs varied with capture depth, but not with the size of the fish. Fish from the greatest depths (40-52 m) exhibited extreme signs less frequently than did those from intermediate depths (30-40 m), possibly as a result of swim bladder gas being vented externally through a rupture in the body wall. All but two fish survived the experiment, and as neither release technique significantly improved short-term survival of the red emperor over non-treatment we see little benefit in promoting either venting or shotline releasing for this comparatively resilient species. Floating vertical enclosures can improve short-term post-release mortality estimates as they overcome many problems encountered when constraining fish in submerged cages.

Role of Native Fish in Integrated Aquatic Weed and Water Quality Management within the Burdekin Irrigation Area

This report summarises work conducted by the QDPI, in partnership with the South Burdekin Water Board (SBWB) and the Burdekin Shire Council (BSC) between 2001 and 2003. The broad aim of the research was to assess the potential of native fish as biocontrol agents for noxious weeds, as part of an integrated program for managing water quality in the Burdekin Irrigation Area. A series of trials were conducted at, or using water derived from, the Sandy Creek Diversion near Groper Creek (lower Burdekin delta). Trials demonstrated that aquatic weeds play a positive role in trapping transient nutrients, until such time that weed growth becomes self-shading and weed dieback occurs, which releases stored nutrients and adversely affects water quality. Transient nutrient levels (av. TN<0.5mg/L; av. TP<0.1mg/L) found in the irrigation channel during the course of this research were substantially lower than expected, especially considering the intensive agriculture and sewage effluent discharge upstream from the study site. This confirms the need to consider the control of weeds rather than complete weed extermination when formulating management plans. However, even when low nutrient levels are available, there is competitive exploitation of habitat variables in the irrigation area leading to succession and eventual domination by certain weed species. During these trials, we have seen filamentous algae, phytoplankton, hyacinth and curled pondweed each hold competitive advantage at certain points. However without intervention, floating weeds, especially hyacinth, ultimately predominate in the Burdekin delta due to their fast propagation rate and their ability to out-shade submerged plants. We have highlighted the complexity of interactions in these highly disturbed ecosystems in that even if the more prevalent noxious weeds are contained, other weed species will exploit the vacant niche. This complexity places stringent requirements on the type of native fish that can be used as biocontrol agents. Of the seven fish species identified with herbivorous trophic niches, most target plankton or algae and do not have the physical capacity to directly eat the larger macrophytes of the delta. We do find however that following mechanical weed harvesting, inoculative releases of fish can slow the rate of hyacinth recolonisation. This occurs by mechanisms in addition to direct weed consumption, such as disturbing growth surfaces by grazing on attached biofilms. Predation by birds and water rats presents another impediment to the efficacy of large-scale releases of fish. However, alternative uses of fish in water quality management in the Burdekin irrigation area are discussed.

Methanotrophs from natural ecosystems for ruminant methane mitigation

Enteric fermentation of methane by ruminant animals represents a major source of anthropogenic methane production. Methane produced in this manner is released to the atmosphere where it is highly efficient at absorbing thermal radiation, which consequently increases the global surface temperature. Although many different strategies to control ruminant methane emissions have been considered, few are currently considered viable. Obligate and acultative methane oxidising bacteria (MOB) and anaerobic methane oxidising archaea (ANME) play a fundamental role in the carbon cycle by metabolising methane before it is released into the atmosphere. Because of this, methanotrophic microorganisms represent a novel biological control agent in mitigating ruminant methane emissions. This project aims to characterise methanotrophic microorganisms from a range of environments, and to subsequently determine the metabolic activity of these microorganisms under in vitro rumen-like conditions.

Lagarosiphon major (Ridley) Moss ex Wager (curly water weed)

Curley water weed is a southern African submerged macrophyte that has become a serious water weed in several countries including New Zealand after its introduction by the aquarium industry. It has been recorded in Australia, including Queensland, but is not considered to have established. The chapter describes the ecology and management of this weed. Control of further dispersal is considered critical to its management. It has also been considered for classical biological control and manipulation of grass carp densities has also been studied. Issues relating to the use of herbicides in freshwater systems are also discussed.

Bacterial Community Structure in the Hindgut of Wild and Captive Dugongs (Dugong dugon)

Dugongs (Dugong dugon) are marine mammals that obtain nutrients through hindgut fermentation of seagrass, however, the microbes responsible have not been identified. This study used denaturing gradient gel electrophoresis (DGGE) and 454-pyrosequencing to profile hindgut bacterial communities in wild dugongs. Faecal samples obtained from 32 wild dugongs representing four size/maturity classes, and two captive dugongs fed on cos lettuce were screened using DGGE. Partial 16S rRNA gene profiles of hindgut bacteria from wild dugong calves and juveniles were grouped together and were different to those in subadults and adults. Marked differences between hindgut bacterial communities of wild and captive dugongs were also observed, except for a single captive whose profile resembled wild adults following an unsuccessful reintroduction to the wild. Pyrosequencing of hindgut communities in two wild dugongs confirmed the stability of bacterial populations, and Firmicutes (average 75.6% of Operational Taxonomic Units [OTUs]) and Bacteroidetes (19.9% of OTUs) dominated. Dominant genera were Roseburia, Clostridium, and Bacteroides. Hindgut microbial composition and diversity in wild dugongs is affected by ontogeny and probably diet. In captive dugongs, the absence of the dominant bacterial DNA bands identified in wild dugongs is probably dependent upon prevailing diet and other captive conditions such as the use of antibiotics. This study represents a first step in the characterisation of a novel microbial ecosystem-the marine hindgut of Sirenia.

Binding of polyphenols to plant cell wall analogues - Part 2: Phenolic acids

Bacterial cellulose and cellulose-pectin composites were used as well-defined model plant cell wall (PCW) systems to study the interaction between phenolic acids (PA) derived from purple carrot juice concentrate (PCJC) and PCW components. Significant PA depletion from solution occurred, with pure cellulose initially (30 s-1 h) absorbing more than cellulose-pectin composites in the first hour (ca 20% cf 10-15%), but with all composites absorbing similar levels (ca 30%) after several days. Individual PAs bound to different relative extents with caffeic acid > chlorogenic acid > ferulic acid. Extrapolation of data for these model systems to carrot puree suggests that nutritionally-significant amounts of PAs could bind to cell walls, potentially restricting bioavailability in the small intestine and, as a consequence, delivering PAs to the large intestine for fermentation and metabolism by gut bacteria. (C) 2012 Elsevier Ltd. All rights reserved.

Investigation of the microbial metabolism of carbon dioxide and hydrogen in the kangaroo foregut by stable isotope probing

Kangaroos ferment forage material in an enlarged forestomach analogous to the rumen, but in contrast to ruminants, they produce little or no methane. The objective of this study was to identify the dominant organisms and pathways involved in hydrogenotrophy in the kangaroo forestomach, with the broader aim of understanding how these processes are able to predominate over methanogenesis. Stable isotope analysis of fermentation end products and RNA stable isotope probing (RNA-SIP) were used to investigate the organisms and biochemical pathways involved in the metabolism of hydrogen and carbon dioxide in the kangaroo forestomach. Our results clearly demonstrate that the activity of bacterial reductive acetogens is a key factor in the reduced methane output of kangaroos. In in vitro fermentations, the microbial community of the kangaroo foregut produced very little methane, but produced a significantly greater proportion of acetate derived from carbon dioxide than the microbial community of the bovine rumen. A bacterial operational taxonomic unit closely related to the known reductive acetogen Blautia coccoides was found to be associated with carbon dioxide and hydrogen metabolism in the kangaroo foregut. Other bacterial taxa including members of the genera Prevotella, Oscillibacter and Streptococcus that have not previously been reported as containing hydrogenotrophic organisms were also significantly associated with metabolism of hydrogen and carbon dioxide in the kangaroo forestomach.The ISME Journal advance online publication, 13 March 2014; doi:10.1038/ismej.2014.25.

Formulation and characterization of drug-loaded microparticles using distiller’s dried grain kafirin

Kafirin, a protein extracted from sorghum grain has been formulated into microparticles, and proposed for use as a delivery system due to the resistance of kafirin to upper gastrointestinal digestion. However, extracting kafirin from sorghum “distiller’s dried grains with solubles” (DDGS) may be more efficient as the carbohydrate component has been removed by fermentation. This study investigated the properties and use of kafirin extracted from DDGS to formulate microparticles. Prednisolone, an anti-inflammatory drug that could benefit from a delayed and targeted delivery system to the colon, was loaded into DDGS kafirin microparticles by phase separation using sodium chloride. Scanning electron micrographs revealed that the empty and prednisolone-loaded microparticles were round in shape and varied in size. Surface binding studies indicated prednisolone was loaded within the microparticles rather than being solely bound on the surface. These findings demonstrate DDGS kafirin can be formulated into microparticles and loaded with medication. Future studies could investigate the potential applications of DDGS kafirin microparticles as an orally administered targeted drug-delivery system.