Biofilm Spreading by the Adhesin-Dependent Gliding Motility of Flavobacterium johnsoniae: 2. Role of Filamentous Extracellular Network and Cell-to-Cell Connections at the Biofilm Surface

Flavobacterium johnsoniae forms a thin spreading colony on nutrient-poor agar using gliding motility. As reported in the first paper, WT cells in the colony were sparsely embedded in self-produced extracellular polymeric matrix (EPM), while sprB cells were densely packed in immature biofilm with less matrix. The colony surface is critical for antibiotic resistance and cell survival. We have now developed the Grid Stamp-Peel method whereby the colony surface is attached to a TEM grid for negative-staining microscopy. The images showed that the top of the spreading convex WT colonies was covered by EPM with few interspersed cells. Cells exposed near the colony edge made head-to-tail and/or side-to-side contact and sometimes connected via thin filaments. Nonspreading sprB and gldG and gldK colonies had a more uniform upper surface covered by different EPMs including vesicles and filaments. The EPM of sprB, gldG, and WT colonies contained filaments ~2 nm and ~5 nm in diameter; gldK colonies did not include the latter. Every cell near the edge of WT colonies had one or two dark spots, while cells inside WT colonies and cells in SprB-, GldG-, or GldK-deficient colonies did not. Together, our results suggest that the colony surface structure depends on the capability to expand biofilm.

Association of Oral Microbiota Properties on Hyaluronidase and Biofilm Formation

Correlation between hyaluronidase (Hyl) activity and biofilm detachment in a few bacterial species was found. However, it is unclear if this association applies to bacterial species or for more general bacterial characteristics. This study determined the association between biofilm production and Hyl activity among bacterial isolates from the oral cavity of healthy subjects, and its association with Gram staining group, colony surface morphology and bacteria shape. The swab was taken from the tongue, cheek and entire teeth surfaces of 35 subjects, and tested for biofilm through modified microtiter plate assay while Hyl production was screened through HA rapid plate method. Forty-four isolates were found, each 50% are Gram-positive, and Gram-negative bacteria, with the majority are cocci and non-mucoid colony. More than 70% of isolates are moderate and strong; (n= 17, 38.6%) and (n=15, 34.1%) respectively for biofilm production; and 68.2% are Hyl producer. A significant association was found between Hyl and bacterial shape (p=0.018) and colony morphology (p=0.018), while other association is not significantly measured, including between Hyl and biofilm (p=0.659). This study showed that biofilm production is not affected by the characteristics of the bacteria to produce or not produce hyaluronidase. Meanwhile, Hyl production is prone in rod shape and mucoid isolates which need further investigations.

Uji rizobakteri agen biokontrol terhadap Rigidosporus microporus pada Tanaman Pala (Myristica fragrans) secara in vitro

Abstrak. Penelitian ini bertujuan untuk mengetahui pengaruh jenis rizobakteri yang berpotensi sebagai agen biokontrol terhadap daya hambat patogen Rigidoporus microporus pada tanaman pala secara in vitro yang dilakukan pada Laboratorium Ilmu dan Teknologi Benih Fakultas Pertanian Universitas Syiah Kuala mulai bulan Maret sampai Mei 2018. Sampel yang digunakan yaitu patogen R. microporus penyebab jamur akar putih (JAP) pada tanaman pala dan isolat rizobakteri dari tanaman yang sehat diantara tanaman yang sakit. Hasil yang diperoleh dari penelitian ini yaitu terdapat 44 isolat rizobakteri murni, setelah diuji daya hambat terdapat 27 isolat rizobakteri yang dapat menghambat patogen R. microporus dan setelah uji antagonisme terdapat 18 isolat rizobakteri yang mampu menekan pertumbuhan koloni patogen R. microporus. Isolat rizobakteri yang memiliki penghambatan paling tinggi terdapat pada AP 5/7 dengan penghambatan 74.44% yang memiliki ciri-ciri bentuk permukaan koloni cembung, berwarna putih, dengan pinggiran koloni tidak rata dan AP 8/2 dengan penghambatan 61.11% yang memiliki ciri-ciri bentuk permukaan koloni rata, berwarna putih, dengan pinggiran koloni tidak rata.Rhizobacterial test of bio control agent toward Rigidosporus microporus on Nutmeg Plants (Myristica fragrans) in vitroAbstract. This study aims to determine the effect of rhizobacteria types that have potential as bio control agents on the pathogenic inhibitory power of Rigidoporus microporus on nutmeg plants in vitro which was conducted at the Laboratory of Seed Science and Technology, Faculty of Agriculture, Syiah Kuala University, from March to May 2018. The samples used were pathogenic R. microporus causing white root fungus (JAP) on nutmeg plants and rhizobacterial isolates from healthy plants among diseased plants. The results obtained from this study is there were 44 pure rhizobacterial isolates, after testing the inhibitory power, there were 27 isolates of rhizobacteria that could inhibit R. microporus pathogens and after antagonism test there were 18 isolates of rhizobacteria that could suppress the growth of R. microporus pathogenic colonies. Rhizobacterial isolates with the highest inhibition were found on AP 5/7 with 74.44% inhibition which had features of convex, white colony surface shape, with uneven colony edges and AP 8/2 with 61.11% inhibition which had features of flat colony surface shape, white colour, with uneven edges of colonies.

Geochronology of Cadmium (Cd), Cuprum (Cu), and Arsenics (As) in Annual Band of Coral Porites lutea at Pantai Kondang Merak, Malang

Coral reef is a massive natural building block that mainly composed of hard coral. In ecological view coral reef is the center of biological activity for shelter, foraging and feeding place. Porites lutea is a common coral in reef flat area such as in Pantai Kondang Merak. This coral can form a massive with hillocky colony surface and has a slow linear extension rate, that made this coral has long longevity. The annual growth band of coral skeleton provide information of pollutants in the coastal extending back over several years ago due to ability of coral aragonite traped trace metal from environment. The aim of this research was to determine the concentration of trace metals of Cd, Cu and As along with the coral annual banding. The heavy metals detection was performed using ICP-OES (iCAP 7400 Series). The concentration of Cd, Cu and As in sample 1 (KM1) were 2.236 mg/kg, 9.726 mg/kg, and 2.474 mg/kg, while sample 2 (KM2) were 1.989 mg/kg, 19.157 mg/kg, and 2,064 mg/kg respectively. Two ways mechanism of trace metals to be trapped in the coral skeleton are by direct mechanism when trace metals in a form dissolved ion that were uptaken by coral then stored into coral skeleton and by indirect mechanism when particulate metals ingested by plankton then eaten by coral through coral tissue. The tracing of heavy metal in coral is provided important information of environment condition of the sea from 2009 - 2015 that may be used for authority decision regarding pollutant ambient in the sea environment.

Impact of excessive sedimentation caused by anthropogenic activities on benthic suspension feeders in the Sea of Marmara

A massive die-off of benthic suspension feeders (BSF) covered by large amounts of sediments was observed along Prince Islands coasts (north-eastern Sea of Marmara) in August 2015. Alcyonarians, pennatulaceans, bivalves and sponges were severely affected. Many BSF probably died from burial and clogging of their feeding and respiratory apparatus. Of the gorgonian colonies, 66 ± 34% (mean ± SD) were dead, while 15 ± 16% (mean ± SD) displayed recent necrosis on the colony surface. In addition, histopathological and microbial examinations of the affected gorgonians and gold corals (Savalia savaglia) suggest that stress caused by sedimentation made them vulnerable to exploitation by consistently isolated opportunistic microorganisms. We isolatedVibrio splendidusandVibrio neptuniusfrom diseased gold coral colonies, but the bacterial isolates obtained from gorgonians could only be identified to genusVibriolevel. The presumably artificially introduced fungusMucor circinelloideswas common on both gold coral and gorgonians. This mould and opportunistic bacteria may have colonized BSF by taking advantage of low oxygen levels leading to impaired coral immune responses and thereby exacerbated the BSF mortality. Construction and landfill operations at Yassıada seem to be the greatest contributor to the observed sedimentation, as shown by silicate concentrations in nearby waters. These observations imply that preventive measures are necessary when construction operations take place in the vicinity of sensitive marine habitats.

Fitting in with the crowd: the role of prospecting in seabird behavioural trends

Prebreeding, subadult seabirds have been documented prospecting or visiting multiple sites throughout the breeding season to gather information on colony reproductive success, identify suitable habitat, evaluate prey abundance, and locate potential partners; however, many aspects of prospector biology remain unknown. We explored prospector behaviour as a means of furthering our understanding of postnatal seabird dispersal and colony attendance using Least Auklets (Aethia pusilla (Pallas, 1811)) and Crested Auklets (Aethia cristatella (Pallas, 1769)) breeding at Gareloi Island, Alaska, in 2014 and 2015. We recorded age class, length of time spent on the colony, and behaviour for individuals attending a study plot over the course of two breeding seasons. Although prospectors typically spent more time on the colony surface than adults, prospectors rarely socialized with conspecifics during their visits to the colony, possibly due to the absence of a citrus-like feather odour used in olfactory communication. Additionally, we found substantial differences between observed and predicted data between years, demonstrating that other factors (likely prey abundance or quality) influenced behaviour in 2015. Our results suggest that the collective knowledge of seabird prospecting behaviour is not necessarily transferable between taxa and there may be a range of strategies employed by prospectors when assessing colonies.

Effects of excavating-sponge removal on coral growth

Some excavating sponges are strong competitors for space on coral reefs, able to kill live coral tissue and to overgrow entire coral colonies. Stony corals with excavating sponges can die or become dislodged. To date no restoration efforts to eliminate excavating sponges from live corals have been considered. In this study we examined the effect and remedial potential of removal of the excavating sponge, Cliona delitrix, by monitoring tissue loss of the stony coral Montastrea cavernosa. Thirty-three corals colonized by the sponge were used: 11 as controls, and 22 as treatments in which sponges were removed using hammer and chisel. After sponge removal, resultant cavities in the coral skeletons were filled with common cement or epoxy. Standardized photos of each coral were taken immediately after sponge removal, and at 6 and 12 months afterwards. Results were similar between fill materials and showed a reduction in coral tissue loss in colonies where the sponge was removed. This study demonstrates that eliminating the bioeroding sponge enables potential recovery in affected stony corals after a year. However, 36% of experimental corals showed renewed presence of C. delitrix on the colony surface within a year after removal, demonstrating the extraordinary ability of this sponge to colonize corals. Although the technique used in this study is applicable to enhance modern coral restoration practices by slowing tissue loss, this method is costly, elaborate, and not suitable at a reef-wide scale. Further restoration alternatives and long-term measures to prevent over-colonization of corals by excavating sponges are encouraged.

An experimental study measuring the effects of a tarsus-mounted tracking device on the behaviour of a small pursuit-diving seabird

Miniaturized tracking devices are taking a rapidly increasing role in studies measuring animal movement and other aspects of behaviour, especially for wide-ranging species such as seabirds that are difficult to observe otherwise. A crucial, but questionable criterion of such migration research is assuming that effects of tracking devices on animal behaviour are negligible, to ensure results of tracking studies are biologically relevant. To address this concern, we experimentally quantified effects of a 2 g (ca. 1.1% of body mass) geolocation device on crested auklet (Aethia cristatella) behaviour, including return rate, activity on the colony surface, and measures of reproductive performance in a two-year, two-part field study. In experiment 1, we fitted tracking devices (or identical dummy devices) to one mate of a breeding pair in nesting crevices, to quantify effects on reproductive performance and nest fidelity. In experiment 2, we assigned dummy devices to birds captured at the colony site surface, to quantify effects on social activity, return rate and provisioning behaviour. For birds tagged in crevices, we detected no effect on fledging success, or chick growth rate (mass and wing length). However, mass at fledging age of chicks provisioned with one tagged parent was significantly lower than control, and low nest site fidelity (compared to control birds) was observed for tagged birds. Individuals tagged on the colony surface showed significantly reduced colony surface activity, return rates and provisioning behaviour. This study shows strong ‘observer effects’ of an attached device well below the recommended size limit for wildlife tagging. Future studies should both quantify effects of attached devices and consider the biological relevance of measures of the behaviour of interest.