Bacterial wilt of ginger in Queensland: Reappraisal of a disease outbreak

In 1955 a severe wilt disease occurring on ginger in the Near North Coast district of Queensland was incorrectly attributed to infection by a Fusarium sp., and later shown to be caused by a strain of Ralstonia solanacearum, now reclassified as R. sequeirae. The disease was brought from China into Australia on latently infected rhizomes, and possibly also with associated soil. Several DNA-based diagnostic methods have shown that the pathogen causing bacterial wilt of ginger in parts of China is indistinguishable from the pathogen uniquely associated with the disease in Queensland. © 2012 Australasian Plant Pathology Society Inc.

Australian monocot-infecting mastrevirus diversity rivals that in Africa

Monocotyledonous plant infecting mastreviruses (family Geminiviridae) have been found in the Old World. The greatest diversity of these viruses has been found in Africa but this may simply reflect the more extensive sampling that has been done there. To provide a better understanding of mastrevirus diversity in Australia. we have sequenced the genomes of 41 virus isolates found in naturalised and native grasses and identified four new species in addition to the four previously characterised species. Two of these species, which were recovered from a single Sporobolus plant, are highly divergent and are most closely related to the African streak viruses. This, coupled with the discovery of divergent dicotyledonous plant infecting mastreviruses in Australia brings into question the hypothesis that mastreviruses may have originated in Africa. We found that the patterns of inter- and intra-species recombination and the recombination hotspots mirror those found in both their African monocot-infecting counterparts and dicot-infecting mastrevirus. (C) 2012 Elsevier B.V. All rights reserved.

Microbial indicators related to yield and disease and changes in soil microbial community structure with ginger farm management practices

TRFLP (terminal restriction fragment length polymorphism) was used to assess whether management practices that improved disease suppression and/or yield in a 4-year ginger field trial were related to changes in soil microbial community structure. Bacterial and fungal community profiles were defined by presence and abundance of terminal restriction fragments (TRFs), where each TRF represents one or more species. Results indicated inclusion of an organic amendment and minimum tillage increased the relative diversity of dominant fungal populations in a system dependant way. Inclusion of an organic amendment increased bacterial species richness in the pasture treatment. Redundancy analysis showed shifts in microbial community structure associated with different management practices and treatments grouped according to TRF abundance in relation to yield and disease incidence. ANOVA also indicated the abundance of certain TRFs was significantly affected by farming system management practices, and a number of these TRFs were also correlated with yield or disease suppression. Further analyses are required to determine whether identified TRFs can be used as general or soil-type specific bio-indicators of productivity (increased and decreased) and Pythium myriotylum suppressiveness.

Microbes in the tailoring of barley malt properties

Microbes have a decisive role in the barley-malt-beer chain. A major goal of this thesis was to study the relationships between microbial communities and germinating grains during malting. Furthermore, the study provided a basis for tailoring of malt properties with natural, malt-derived microbes. The malting ecosystem is a dynamic process, exhibiting continous change. The first hours of steeping and kilning were the most important steps in the process with regard to microbiological quality. The microbial communities consisting of various types of bacteria, yeasts and filamentous fungi formed complex biofilms in barley tissues and were well-protected. Inhibition of one microbial population within the complex ecosystem led to an increase of non-suppressed populations, which must be taken into account because a shift in microbial community dynamics may be undesirable. Both bacterial and fungal communities should be monitored simultaneously. Using different molecular approaches we showed that the diversity of microbes in the malting ecosystem was greater than expected. Even some new microbial groups were found in the malting ecosystem. Suppression of Gram-negative bacteria during steeping was advanategous for grain germination and malt brewhouse performance. Fungal communities including both filamentous fungi and yeasts significantly contributed to the production of microbial beta-glucanases and xylanases, and were also involved in proteolysis. Well-characterized lactic acid bacteria (Lactobacillus plantarum VTT E-78076 and Pediococcus pentosaceus VTT E-90390) proved to be an effective way of balancing the microbial communities in malting. Furthermore, they had positive effects on malt characteristics and notably improved wort separation. Previously the significance of yeasts in the malting ecosystem has been largely underestimated. This study showed that yeast community was an important part of the industrial malting ecosystem. Yeasts produced extracellular hydrolytic enzymes with a potentially positive contribution to malt processability. Furthermore, several yeasts showed strong antagonistic activity against field and storage moulds. Addition of a selected yeast culture (Pichia anomala VTT C-04565) into steeping restricted Fusarium growth and hydrophobin production and thus prevented beer gushing. Addition of P. anomala C565 into steeping water tended to retard wort filtration, but the filtration was improved when the yeast culture was combined with L. plantarum E76. The combination of different microbial cultures offers a possibility to use ther different properties, thus making the system more robust. Improved understanding of complex microbial communities and their role in malting enables a more controlled process management and the production of high quality malt with tailored properties

Responses of soil microbial communities to clonal variation of Norway spruce

In boreal forests, microorganisms have a pivotal role in nutrient and water supply of trees as well as in litter decomposition and nutrient cycling. This reinforces the link between above-ground and below-ground communities in the context of sustainable productivity of forest ecosystems. In northern boreal forests, the diversity of microbes associated with the trees is high compared to the number of distinct tree species. In this thesis, the aim was to study whether conspecific tree individuals harbour different soil microbes and whether the growth of the trees and the community structure of the associated microbes are connected. The study was performed in a clonal field trial of Norway spruce, which was established in a randomized block design in a clear-cut area. Since out-planting in 1994, the spruce clones showed two-fold growth differences. The fast-growing spruce clones were associated with a more diverse community of ectomycorrhizal fungi than the slow-growing spruce clones. These growth performance groups also differed with respect to other aspects of the associated soil microorganisms: the species composition of ectomycorrhizal fungi, in the amount of extraradical fungal mycelium, in the structure of bacterial community associated with the mycelium, and in the structure of microbial community in the organic layer. The communities of fungi colonizing needle litter of the spruce clones in the field did not differ and the loss of litter mass after two-years decomposition was equal. In vitro, needles of the slow-growing spruce clones were colonized by a more diverse community of endophytic fungi that were shown to be significant needle decomposers. This study showed a relationship between the growth of Norway spruce clones and the community structure of the associated soil microbes. Spatial heterogeneity in soil microbial community was connected with intraspecific variation of trees. The latter may therefore influence soil biodiversity in monospecific forests.

Microbial life and deposits in paper machine circuits

Väitöskirjani käsittele mikrobien ja erilaisten kemikaalien rooleja saostumien ja biofilmien muodostumisessa paperi- ja kartonkikoneilla. "Saostuma" tässä työssä tarkoittaa kiinteän aineen kertymää konepinnoille tai rajapinnoille konekierroissa, jotka on tarkoitettu massasulppujen, lietteiden, vesien tai ilman kuljetukseen. Saostumasta tulee "biofilmi" silloin kun sen oleellinen rakennekomponentti on mikrobisolut tai niiden tuotteet. Väitöstyöni työhypoteesina oli, että i. tietämys saostumien koostumuksesta, sekä ii. niiden rakenteesta, biologisista, fysikaalis-kemiallisista ja teknisistä ominaisuuksista ohjaavat tutkijaa löytämään ympäristöä säästäviä keinoja estää epätoivottujen saostumien muodostus tai purkaa jo muodostuneita saostumia. Selvittääkseni saostumien koostumista ja rakennetta käytin monia erilaisia analytiikan työkaluja, kuten elektronimikroskopiaa, konfokaali-laser mikroskopiaa (CLSM), energiadispersiivistä röntgenanalyysiä (EDX), pyrolyysi kaasukromatografiaa yhdistettynä massaspektrometriaan (Py-GCMS), joninvaihtokromatografiaa, kaasukromatografiaa ja mikrobiologisia analyysejä. Osallistuin aktiivisesti innovatiivisen, valon takaisinsirontaan perustuvan sensorin kehittämistyöhön, käytettäväksi biofilmin kasvun mittaukseen suoraan koneen vesikierroista ja säiliöistä. Työni osoitti, että monet paperinvalmistuksessa käytetyistä kemikaaleista reagoivat keskenään tuottaen orgaanisia tahmakerroksia konekiertojen teräspinnoille. Löysin myös kerrostumia, jotka valomikroskooppisessa tarkastelussa oli tulkittu mikrobeiksi, mutta jotka elektronimikroskopia paljasti alunasta syntyneiksi, alumiinihydroksidiksi joka saostui pH:ssa 6,8 kiertokuitua käyttävän koneen viiravesistä. Monet paperintekijät käyttävät vieläkin alunaa kiinnitysaineena vaikka prosessiolot ovat muuttuneet happamista neutraaleiksi. Sitä pidetään paperitekijän "aspiriinina", mutta väitöstutkimukseni osoitti sen riskit. Löysin myös orgaanisia saostumia, joiden alkuperä oli aineiden, kuten pihkan, saippuoituminen (kalsium saippuat) niin että muodostui tahmankasvua ylläpitävä alusta monilla paperi- ja kartonkikoneilla. Näin solumuodoiltaan Deinococcus geothermalista muistuttavia bakteereita kasvamassa lujasti teräskoepalojen pintaan kiinnittyneinä pesäkkeinä, kun koepaloja upotettiin paperikoneiden vesikiertoihin. Nämä deinokokkimaiset pesäkkeet voivat toimia jalustana, tarttumisalustana muiden mikrobien massoille, joka selittäisi miksi saostumat yleisesti sisältävät deinokokkeja pienenä, muttei koskaan pääasiallisena rakenneosana. Kun paperikoneiden käyttämien vesien (raakavedet, lämminvesi, biologisesti puhdistettu jätevesi) laatua tutkitaan, mittausmenetelmällä on suuri merkitys. Koepalan upotusmenetelmällä todettu biofilmikasvu ja viljelmenetelmällä mitattu bakteerisaastuneisuus korreloivat toisiinsa huonosti etenkin silloin kun likaantumisessa oli mukana rihmamaiseti kasvavia bakteereja. Huoli ympäristöstä on pakottanut paperi- ja kartonkikoneiden vesikiertojen sulkemiseen. Vesien kierrätys ja prosessivesien uudelleenkäyttö nostavat prosessilämpötilaa ja lisäävät koneella kiertävien kolloidisten ja liuenneiden aineiden määriä. Tutkin kiertovesien pitoisuuksia kolmessa eriasteisesti suljetussa tehtaassa, joiden päästöt olivat 0 m3, 0,5 m3 ja 4 m3 jätevettä tuotetonnia kohden, perustuen puhdistetun jäteveden uudelleen käyttöön. Nollapäästöisellä tehtaalla kiertovesiin kertyi paljon orgaanisesti sidottua hiiltä (> 10 g L-1), etenkin haihtuvina happoina (maito-, etikka-, propioni- ja voi-). Myös sulfaatteja, klorideja, natriumia ja kalsiumia kertyi paljon, > 1 g L-1 kutakin. Pääosa (>40%) kaikista bakteereista oli 16S rRNA geenisekvenssianalyysien tulosten perusteella sukua, joskin etäistä (< 96%) ainoastaan Enterococcus cecorum bakteerille. 4 m3 päästävältä tehtaalta löytyi lisäksi Bacillus thermoamylovorans ja Bacillus coagulans. Tehtaiden saostumat sisälsivät arkkeja suurina pitoisuuksina, ≥ 108 g-1, mutta tunnistukseen riittävää sekvenssisamanlaisuutta löytyi vain yhteen arkkisukuun, Methanothrix. Tutkimustulokset osoittivat että tehtaan vesikiertojen sulkeminen vähensi rajusti mikrobiston monimuotoisuutta, muttei estänyt liuenneen aineen ja kiintoaineen mineralisoitumista.

Mitochondrial DNA diversity of Cleruchoides noackae (Hymenoptera: Mymaridae): a potential biological control agent for Thaumastocoris peregrinus (Hemiptera: Thaumastocoridae)

Carpintero and Dellap, (Hemiptera: Thaumastocoridae) is a native Australian sap-feeding insect that has become invasive and seriously damaging to commercially grown in the Southern Hemisphere. Lin and Huber (Hymenoptera: Mymaridae) was recently discovered as an egg parasitoid of the Thaumastocoridae in Australia. Mitochondrial DNA (mtDNA; cytochrome oxidase subunit I, COI) sequence diversity amongst 104 individuals from these native populations revealed 24 sequence haplotypes. The COI haplotypes of individuals collected from the Sydney and Southeast Queensland clustered in distinct groups, indicating limited spread of the insect between the regions. Individuals collected from Perth in Western Australia were represented by four COI haplotypes. Although this population is geographically more isolated from other populations, two COI haplotypes were identical to haplotypes found in the Sydney region. The results suggest that has recently been introduced into Perth, possibly from the Sydney area. The high mtDNA diversity and limited spread that is suggested for is in contrast to the lack of geographic associated mtDNA diversity and extensive spread of . If implemented as a biological control agent, this factor will need to be considered in collecting and releasing .

Genetic diversity and microcystin production by Anabaena in the Gulf of Finland, Baltic Sea

Syanobakteerit (sinilevät) ovat olleet Itämeressä koko nykymuotoisen Itämeren ajan, sillä paleolimnologiset todisteet niiden olemassaolosta Itämeren alueella ovat noin 7000 vuoden takaa. Syanobakteerien massaesiintymät eli kukinnat ovat kuitenkin sekä levinneet laajemmille alueille että tulleet voimakkaimmiksi viimeisten vuosikymmenien aikana. Tähän on osasyynä ihmisten aiheuttama kuormitus, joka rehevöittää Itämerta. Suomenlahti, jota tämä tutkimus käsittelee, on kärsinyt tästä rehevöitymiskehityksestä muita Itämeren altaita enemmän. Syanobakteerit muodostavat jokakesäisiä kukintoja Suomenlahdella - niin sen avomerialueilla kuin rannoillakin. Yleisimmät kukintoja muodostavat syanobakteerisuvut ovat Nodularia, Anabaena ja Aphanizomenon. Kukinnat aiheuttavat paitsi esteettistä haittaa myös terveydellisen riskitekijän. Niiden myrkyllisyys liitetään usein Nodularia-suvun tuottamaan nodulariini-maksamyrkkyyn. Itämeren Aphanizomenon-suvun on todettu olevan myrkytön. Vaikka Itämeren kukintoja aiheuttavista Nodularia- ja Aphanizomenon-syanobakteereista tiedetään varsin paljon, on molekyylimenetelmiin pohjautuva syanobakteeritutkimus ohittanut Itämeren Anabaena-suvun monelta osin. Tämän työn tarkoituksena oli syventää käsitystämme Itämeren Anabaena-syanobakteerista, sen mahdollisesta myrkyllisyydestä, geneettisestä monimuotoisuudesta ja fylogeneettisista sukulaisuussuhteista. Tässä työssä eristettiin 49 planktista Anabaena-kantaa, joista viisi tuottivat mikrokystiinejä. Tämä oli ensimmäinen yksiselitteinen todiste, että Itämeren Anabaena tuottaa maksamyrkyllisiä mikrokystiini-yhdisteitä. Jokainen eristetty myrkyllinen Anabaena-kanta tuotti useita mikrokystiini-variantteja. Lisäksi mikrokystiinejä löydettiin kukintanäytteistä, joissa oli myrkkyä syntetisoivia geenejä sisältäneitä Anabaena-syanobakteereita. Myrkkyjä löydettiin molempina tutkimusvuosina 2003 ja 2004. Myrkkyjen esiintyminen ei siten ollut vain yksittäinen ilmiö. Tässä työssä saimme viitteitä siitä, että maksamyrkyllinen Anabaena-syanobakteeri esiintyisi vähäsuolaisissa vesissä. Tämä riippuvuussuhde jää kuitenkin tulevien tutkimuksien selvitettäväksi. Tässä työssä havaittiin mikrokystiinisyntetaasi-geenien inaktivoituminen Itämeren Anabaena-kannassa ja kukintanäytteissä. Kuvasimme Anabaena-kannan mikrokystiinisyntetaasigeenien sisältä insertioita, jotka hyvin todennäköisesti inaktivoivat myrkyntuoton. Insertion sisältäneeltä kannalta löysimme kuitenkin kaikki mikrokystiinisyntetaasigeenit osoittaen, että geenien olemassaolo ei välttämättä varmista kannan mikrokystiinintuottoa. Mielenkiintoista oli se, että inaktivaation aiheuttavia insertioita löytyi kukintanäytteistä molemmilta tutkimusvuosilta. Vastaavia insertioita ei kuitenkaan löydetty makean veden Anabaena-kannoista tai järvinäytteistä. On yleistä, että syanobakteerikukinnoista löytyy usean syanobakteerisuvun edustajia. Myrkyllisiä sukuja tai lajeja ei voida kuitenkaan erottaa mikroskooppisesti myrkyttömistä. Käsillä olevassa tutkimuksessa kehitettiin molekyylimenetelmä, jolla on mahdollista määrittää kukinnan mahdollisesti maksamyrkylliset syanobakteerisuvut. Tätä menetelmää sovellettiin Itämeren kukintojen tutkimiseen. Itämeren pintavesistä ja ranta-alueiden pohjasta eristetyt Anabaena-kannat osoittautuivat geneettisesti monimuotoisiksi. Tämä Anabaena-syanobakteerien geneettinen monimuotoisuus vahvistettiin monistamalla geenejä suoraan kukintanäytteistä ilman kantojen eristystä. Makeiden vesien ja Itämeren Anabaena-kannat ovat geneettisesti hyvin samankaltaisia. Geneettisissä vertailuissa kävi kuitenkin ilmi, että pohjassa elävien Anabaena-kantojen geneettinen monimuotoisuus oli suurempaa kuin pintavesistä eristettyjen kantojen. Itämeren Anabaena-kantojen sekvenssit muodostivat omia ryhmiä sukupuun sisällä, jolloin on mahdollista, että nämä edustavat Itämeren omia Anabaena-ekotyyppejä. Tämä tutkimus oli ensimmäinen, jossa uusin molekyylimenetelmin systemaattisesti selvitettiin Itämeren Anabaena-syanobakteerin geneettistä populaatiorakennetta, fylogeniaa ja myrkyntuottoa. Tulevaisuudessa monitorointitutkimuksissa on otettava huomioon myös Itämeren Anabaena-syanobakteerin mahdollinen maksamyrkyntuotto – erityisesti vähäsuolaisemmilla rannikkovesillä.

A convenient sample preparation protocol for scanning electron microscope examination of xylem-occluding bacterial biofilm on cut flowers and foliage

Microbes and their exopolysaccharides (EPS) can block xylem vessels, thereby increasing the hydraulic resistance and decreasing the vase life of cut flowers and foliage. Scanning electron microscopy (SEM) provides a powerful tool for investigation of bacteria-induced xylem occlusion. However, conventional preparation protocols for SEM involving chemicals can cause loss of hydrated EPS material, and thereby damage the bacterial biofilms during dehydration. A modified chemical fixation protocol involving pre-fixation with 75 mM lysine plus 2.5% glutaraldehyde followed by the normal fixation in 3% glutaraldehyde was, therefore, tested for improved preservation of bacterial biofilm at the stem-ends of cut Acacia holosericea foliage stems. Stem-end segments with different stages of bacterial growth were obtained from stems stood into water. The lysine-based protocol was compared with four other processing protocols of critical point drying (CPD) without fixation (control), freeze-drying (FD), conventional chemical fixation followed by drying with hexamethyldisilazane (HMDS), and conventional chemical fixation with CPD. The non-fixed control. FD and the glutaraldehyde fixation with HMDS drying gave poor preservation of hydrated material, including bacterial EPS. Conventional glutaraldehyde fixation followed by CPD was superior to these three methods in terms of better preserving the EPS. However, this fourth method gave condensation of biofilms during dehydration. In contrast, the modified lysine-based protocol resulted in superior preservation of EPS and biofilm structure. Thus, this fifth method was the most appropriate for examination of bacterial stem-end blockage in cut ornamentals. (C) 2012 Elsevier B.V. All rights reserved.

Weakening of the Gram-negative bacterial outer membrane - A tool for increasing microbiological safety

Gram-negative bacteria are harmful in various surroundings. In the food industy their metabolites are potential cause of spoilage and this group also includes many severe or potential pathogens, such as Salmonella. Due to their ability to produce biofilms Gram-negative bacteria also cause problems in many industrial processes as well as in clinical surroundings. Control of Gram-negative bacteria is hampered by the outer membrane (OM) in the outermost layer of the cells. This layer is an intrinsic barrier for many hydrophobic agents and macromolecules. Permeabilizers are compounds that weaken OM and can thus increase the activity of antimicrobials by facililating entry of hydrophobic compounds and macromolecules into the cell where they can reach their target sites and inhibit or destroy cellular functions. The work described in this thesis shows that lactic acid acts as a permeabilizer and destabilizes the OM of Gram-negative bacteria. In addition, organic acids present in berriers, i.e. malic, sorbic and benzoic acid, were shown to weaken the OM of Gram-negative bacteria. Organic acids can poteniate the antimicrobial activity of other compounds. Microbial colonic degradation products of plant-derived phenolic compounds (3,4-dihydroxyphenylacetic acid, 3-hydroxyphenylacetic acid, 3,4-dihydroxyphenylpropionic acid, 4-hydroxyphenylpropionic acid, 3-phenylpropionic acid and 3-hydroxyphenylpropionic acid) efficiently destabilized OM of Salmonella. The studies increase our understanding of the mechanism of action of the classical chelator, ethylenediaminetetra-acetic acid (EDTA). In addition, the results indicate that the biocidic activity of benzalkonium chloride against Pseudomonas can be increased by combined use with polyethylenimine (PEI). In addition to PEI, several other potential permeabilizers, such as succimer, were shown to destabilize the OM of Gram-negative bacteria. Furthermore, combination of the results obtained from various permeability assays (e.g. uptake of a hydrophobic probe, sensitization to hydrophobic antibiotics and detergents, release of lipopolysaccharide (LPS) and LPS-specific fatty acids) with atomic force microscopy (AFM) image results increases our knowledge of the action of permeabilizers.

Combining ability, genetic diversity and heterosis in relation to F1 performance of tropically adapted shrunken (sh2) sweet corn lines

With 6 tables Abstract The objectives of this study were to evaluate the importance of heterosis for agronomic and quality traits in shrunken (sh2) sweet corn, assess the usefulness of combining ability to predict the value of parents and their crosses for further genetic improvement and examine whether genetic divergence can predict heterosis or F1 performance. Ten genetically diverse shrunken (sh2) sweet corn inbred lines were used to generate 45 F1s. F1s and parents were evaluated for agronomic and quality traits across environments. Heterosis was more important for yield-related traits than it was for ear aspects and eating quality. Heterosis for most traits was mostly dependent on dominance genetic effects of parental lines. Parents and F1per se performance were highly correlated with general combining ability effects and mid-parent values, respectively, for most traits. Hybrid performance for flavour and plant height was significantly but weakly related to simple sequence repeat (SSR)-based genetic distance (GD). Phenotypic distance (PD), estimated from phenotypic traits was correlated with heterosis for total soluble solids, ear length and flavour. © 2012 State of Queensland.

Äidinmaito - terveysjuomaa ja normaalibakteereita

The chemical composition of breast milk has been studied in detail in the past decades. Hundreds of new antibacterial and antiviral components have been found. Several molecules have been found to promote the proper function of neonatal intestine. However, microbiological studies of breast milk have been, until recently, focused mainly on detecting harmful and pathogenic bacteria and viruses. Natural microbial diversity of human milk has not been widely studied before the work reported in this thesis. This is mainly because breast milk has traditionally been thought to be sterile - even if a certain amount of commensal bacteria have usually been detected in milk samples. The first part of this licentiate thesis contains a short literature review about the anatomy and physiology of breast feeding, human milk chemical and microbiological composition, mastitis, intestinal flora and bacteriocins. The second part reports on the experiments of the licentiate work, concentrating on the microbial diversity in the milk of healthy breast-feeding mothers, and the ability of these bacteria to produce antibacterial substances against pathogenic bacteria. The results indicate that human milk is a source of commensal bacteria for infant intestine. 509 random isolates from 40 breast milk samples were isolated and identified by 16S rRNA sequencing. Median bacterial count was about 600 colony forming units per milliliter. Over half of the isolates were staphylococci, and almost one third streptococci. The most common species were skin bacteria Staphylococcus epidermidis and oral bacteria Streptococcus salivarius and Streptococcus mitis. Lactic acid bacteria, identified as members of Lactobacillus-, Lactococcus- and Leuconostoc -genera, were found in five milk samples. Enterococci were found in three samples. A novel finding in this study is the capability of these commensal bacteria to inhibit the growth of pathogens. In 90 precent of the milk samples commensal bacteria inhibiting the growth of Staphylococcus aureus were found. In 40 precent of samples the colonies could block the growth completely. One fifth of the isolated Staph. epidermidis strains, half of Str. salivarius strains, and all lactic acid bacteria and enterococci could inhibit or block the growth of Staph. aureus. In further study also Listeria innocua- and Micrococcus luteus active isolates were found in 33 and 11 precent of milk samples (out of 140). Furthermore, two Lactococcus lactis isolates from the breast milk were shown to produce bacteriocin nisin, which is an antimicrobial molecule used as a food preservative. The importance of these human milk commensal bacteria in the development of newborn intestinal flora and immune system, as well as in preventing maternal breast infections, should be further explored.

High global diversity of cycloviruses amongst dragonflies

Members of the family Circoviridae, specifically the genus Circovirus, were thought to infect only vertebrates; however, members of a sister group under the same family, the proposed genusCyclovirus, have been detected recently in insects. In an effort to explore the diversity of cycloviruses and better understand the evolution of these novel ssDNA viruses, here we present five cycloviruses isolated from three dragonfly species (Orthetrum sabina, Xanthocnemis zealandica and Rhionaeschna multicolor) collected in Australia, New Zealand and the USA, respectively. The genomes of these five viruses share similar genome structure to other cycloviruses, with a circular ~1.7 kb genome and two major bidirectionally transcribed ORFs. The genomic sequence data gathered during this study were combined with all cyclovirus genomes available in public databases to identify conserved motifs and regulatory elements in the intergenic regions, as well as determine diversity and recombinant regions within their genomes. The genomes reported here represent four different cyclovirus species, three of which are novel. Our results confirm that cycloviruses circulate widely in winged-insect populations; in eight different cyclovirus species identified in dragonflies to date, some of these exhibit a broad geographical distribution. Recombination analysis revealed both intra-and inter-species recombination events amongst cycloviruses, including genomes recovered from disparate sources (e.g. goat meat and human faeces). Similar to other well-characterized circular ssDNA viruses, recombination may play an important role in cyclovirus evolution. © 2013 SGM.