Antimicrobial Activity of Enterococci Isolated from Raw Milk

Enterokoki imaju važnu tehnološku i higijensku ulogu u proizvodnji hrane životinjskog podrijetla. U ovom istraživanju izoliran je soj Enterococcus faecalis 101 iz sirovog mlijeka te je ispitan njegov inhibicijski potencijal prema izolatima bakterije L. monocytogenes iz hrane. Agar spot i agar difuzijskim testom utvrđene su zone inhibicije rasta L. monocytogenes ATCC 7644 i 6 izolata L. monocytogenes iz hrane primjenom neutraliziranog nadtaloga kulture E. faecalis što može biti rezultat djelovanja enterocina. Smanjenje populacije L. monocytogenes ATCC 7644 za 4-5 log zabilježeno je i u tekućim hranilištima primjenom kulture E. faecalis 101 odnosno nadtaloga. Ovi povoljni preliminarni rezultati preduvjet su za daljnju karakterizaciju soja s obzirom na sintezu enterocina i moguću biozaštitnu ulogu u pokusnoj proizvodnji hrane.Enterococci represents important foodborne bacteria from technological and hygienic point of view. In this study, Enterococcus faecalis 101 was isolated from raw milk and subjected to testing its antilisterial activity. Inhibition zones were observed toward L. monocytogenes ATCC 7644 and 6 food-originated strains of L. monocytogenes by agar spot and agar difusion methods by applying neutralized supernatant of E. faecalis. Reduction of L. monocytogenes ATCC 7644 by 4-5 log was found in liquid media inoculated with E. faecalis 101 culture and supernatant, respectively. These promising preliminary results are prerequisites for further characterization of the strain with regard to enterocin sinthesis and posible protective role in experimental food production

Antimikrobni potencijal enterokoka izdvojenih iz sirovog mlijeka

Enterokoki imaju važnu tehnološku i higijensku ulogu u proizvodnji hrane životinjskog podrijetla. U ovom je istraživanju istražen inhibicijski potencijal soja Enterococcus faecalis 101 iz sirovog mlijeka prema sojevima L. monocytogenes iz hrane. Agar-spot i agar-difuzijskim testom utvrđene su zone inhibicije rasta L. monocytogenes ATCC 7644 i 6 izolata L. monocytogenes iz hrane primjenom neutraliziranog nadtaloga kulture E. faecalis, što može biti rezultat djelovanja enterocina. Smanjenje populacije L. monocytogenes ATCC 7644 za 4 – 5 log zabilježeno je i u tekućim hranilištima primjenom kulture, odnosno nadtaloga. Ovi povoljni preliminarni rezultati preduvjet su za daljnju karakterizaciju soja s obzirom na sintezu enterocina i moguću biozaštitnu ulogu u pokusnoj proizvodnji hrane

Khảo sát quy trình khử trùng mẫu, ảnh hưởng của cường độ ánh sáng, nồng độ môi trường agar lên sự hình thành mô sẹo rong Kappaphycus alvarezii (Doty) Doty (Rhodophyta) trong điều kiện in vitro

Objective of this study was to ascertain the optimum condition for callus induction of K. alvarezii (Doty) in vitro such as to determine the explants sterilization process, the effect of intensity of light and the concentration of agar. Fresh thalli treated with 0.5% - 1% detergent for 5 mins followed by 0.5% - 1% betadine for 2 – 3 mins and incubated with 0.5% - 1% broad spectrum antibiotic mixture in PES medium for 1 day produced 95 – 98% bacteria free healthy explants.  Two independent experiments with light intensity and agar contentration of the environment were carried out at 5 different levels of 0, 5, 25, 50, 70 µmol photon.m2.s-1 and 9 agar concentrations of 0.5%, 0.75%; 1.0%, 1.25%, 1.5%, 1.75%, 2.0%, 2.5%, 3.0%. The highest callus induction rate was (96 ± 3.5 – 98 ± 2.1%) at 5 - 25 µmol photon.m-2.s-1 and (87 ± 5.8% – 90 ± 5.0%) in 1% - 3% agar concentration after 2 weeks of explants. The highest callus living rate was 98% at the light intensity of 25 µmol photon.m-2.s-1 and (75 ± 5.7 – 84 ± 1.1%) in 0.75 – 1.5% agar concentration after 2 months of explants. The highest callus re-induction rate was 50 – 55% at the light intensity of 5 – 25 µmol photon.m-2.s-1 and 60 – 65% in 1 – 1.5% agar concentration. Callus was not observed in dark condition (0 µmol photon.m-2.s-1). These calluses, that were strong, big and had filamentous type, will be a good material for the next production stage of embryonic callus production and seedling regeneration from micropropagules.Mục đích của nghiên cứu là xác định điều kiện tối ưu lên sự hình thành mô sẹo của rong sụn Kappaphycus alvarezii (Doty) trong điều kiện in vitro như: quy trình khử trùng mẫu, ảnh hưởng của cường độ ánh sáng và nồng độ môi trường agar. Kết quả rong được khử trùng với 0,5% - 1% chất tẩy rửa trong thời gian 5 phút, kết hợp với 0,5% - 1% betadine trong thời gian 2 – 3 phút, cuối cùng xử lí với 0,5% - 1% kháng sinh phổ rộng trong thời gian 1 ngày thu được hơn 95 – 98 % mẫu rong vô khuẩn. Hai thí nghiệm độc lập được bố trí với ánh sáng và hàm lượng agar trong môi trường thạch, ở 5 mức ánh sáng (0, 5, 25, 50, 70 µmol photon/m2/s) và ở 9 mức nồng độ agar (0,5%; 0,75%; 1,0%, 1,25%, 1,5%, 1,75%, 2,0%, 2,5%, 3,0 %). Kết quả tỷ lệ hình thành mô sẹo cao nhất là (96 ± 3,5 – 98 ± 2,1%) ở 5 - 25 µmol photon/m2/s và (87 ± 5,8% – 90 ± 5,0%) ở nồng độ agar 1% - 3% sau 2 tuần cấy mô. Tỷ lệ sống của mô sẹo cao nhất (98%) ở cường độ ánh sáng 25 µmol photon/ m2/s và ở nồng độ agar 0,75 – 1,5% là (75 ± 5,7 – 84 ± 1,1%) sau 2 tháng cấy mô. Tỷ lệ tái sản xuất mô sẹo cao nhất là 50 – 55% ở cường độ ánh sáng 5 – 25 µmol photon.m-2.s-1 và 60 – 65% ở nồng độ agar 1 – 1.5%. Không có mô sẹo hình thành ở điều kiện tối (0 µmol photon/m-2/s). Những mô sẹo phát triển tốt, có dạng sợi, cụm mô to sẽ là vật liệu tốt để làm những thí nghiệm tiếp theo ở công đoạn sản xuất phôi mô sẹo và tái sinh cây con từ phôi mô sẹo

Antimikrobni potencijal enterokoka izdvojenih iz sirovog mlijeka

Enterokoki imaju važnu tehnološku i higijensku ulogu u proizvodnji hrane životinjskog podrijetla. U ovom je istraživanju istražen inhibicijski potencijal soja Enterococcus faecalis 101 iz sirovog mlijeka prema sojevima L. monocytogenes iz hrane. Agar-spot i agar-difuzijskim testom utvrđene su zone inhibicije rasta L. monocytogenes ATCC 7644 i 6 izolata L. monocytogenes iz hrane primjenom neutraliziranog nadtaloga kulture E. faecalis, što može biti rezultat djelovanja enterocina. Smanjenje populacije L. monocytogenes ATCC 7644 za 4 – 5 log zabilježeno je i u tekućim hranilištima primjenom kulture, odnosno nadtaloga. Ovi povoljni preliminarni rezultati preduvjet su za daljnju karakterizaciju soja s obzirom na sintezu enterocina i moguću biozaštitnu ulogu u pokusnoj proizvodnji hrane

Ecological restoration success is higher for natural regeneration than for active restoration in tropical forests

Is active restoration the best approach to achieve ecological restoration success (the return to a reference condition, that is, old-growth forest) when compared to natural regeneration in tropical forests? Our meta-analysis of 133 studies demonstrated that natural regeneration surpasses active restoration in achieving tropical forest restoration success for all three biodiversity groups (plants, birds, and invertebrates) and five measures of vegetation structure (cover, density, litter, biomass, and height) tested. Restoration success for biodiversity and vegetation structure was 34 to 56% and 19 to 56% higher in natural regeneration than in active restoration systems, respectively, after controlling for key biotic and abiotic factors (forest cover, precipitation, time elapsed since restoration started, and past disturbance). Biodiversity responses were based primarily on ecological metrics of abundance and species richness (74%), both of which take far less time to achieve restoration success than similarity and composition. This finding challenges the widely held notion that natural forest regeneration has limited conservation value and that active restoration should be the default ecological restoration strategy. The proposition that active restoration achieves greater restoration success than natural regeneration may have arisen because previous comparisons lacked controls for biotic and abiotic factors; we also did not find any difference between active restoration and natural regeneration outcomes for vegetation structure when we did not control for these factors. Future policy priorities should align the identified patterns of biophysical and ecological conditions where each or both restoration approaches are more successful, cost-effective, and compatible with socioeconomic incentives for tropical forest restoration

Predicting Java Computer Programming Task Difficulty Levels Using EEG for Educational Environments

Understanding how difficult a learning task is for a person allows teaching material to be appropriately designed to suit the person, especially for programming material. A first step for this would be to predict on the task difficulty level. While this is possible through subjective questionnaire, it could lead to misleading outcome and it would be better to do this by tapping the actual thought process in the brain while the subject is performing the task, which can be done using electroencephalogram. We set out on this objective and show that it is possible to predict easy and difficult levels of mental tasks when subjects are attempting to solve Java programming problems. Using a proposed confidence threshold, we obtained a classification performance of 87.05% thereby showing that it is possible to use brain data to determine the teaching material difficulty level which will be useful in educational environments

Tropical secondary forest regeneration conserves high levels of avian phylogenetic diversity

Secondary forests are promoted as having pivotal roles in reversing the tropical extinction crisis. While secondary forests recover carbon and species over time, a key question is whether phylogenetic diversity—the total evolutionary history across all species within a community—also recovers. Conserving phylogenetic diversity protects unique phenotypic and ecological traits, and benefits ecosystem functioning and stability. We examined the extent to which avian phylogenetic diversity recovers in secondary forests in the Colombian Chocó-Andes. sesPD, a measure of phylogenetic richness corrected for species richness, recovered to old-growth forest levels after ~ 30 years, while sesMPD, a measure of the phylogenetic distance between individuals in a community, recovered to old-growth levels even within young secondary forest. Mean evolutionary distinctiveness also recovered rapidly in secondary forest communities. Our results suggest that secondary forests can play a vital role in conserving distinct evolutionary lineages and high levels of evolutionary history. Focusing conservation and carbon-based payments for ecosystem services on secondary forest recovery and their subsequent protection thus represent a good use of scarce conservation resources

Optically pure, water-stable metallo-helical ‘flexicate’ assemblies with antibiotic activity

The helicates—chiral assemblies of two or more metal atoms linked by short or relatively rigid multidentate organic ligands—may be regarded as non-peptide mimetics of α-helices because they are of comparable size and have shown some relevant biological activity. Unfortunately, these beautiful helical compounds have remained difficult to use in the medicinal arena because they contain mixtures of isomers, cannot be optimized for specific purposes, are insoluble, or are too difficult to synthesize. Instead, we have now prepared thermodynamically stable single enantiomers of monometallic units connected by organic linkers. Our highly adaptable self-assembly approach enables the rapid preparation of ranges of water-stable, helicate-like compounds with high stereochemical purity. One such iron(II) ‘flexicate’ system exhibits specific interactions with DNA, promising antimicrobial activity against a Gram-positive bacterium (methicillin-resistant Staphylococcus aureus, MRSA252), but also, unusually, a Gram-negative bacterium (Escherichia coli, MC4100), as well as low toxicity towards a non-mammalian model organism (Caenorhabditis elegans)

Signal transduction in a covalent post-assembly modification cascade

Natural reaction cascades control the movement of biomolecules between cellular compartments. Inspired by these systems, we report a synthetic reaction cascade employing post-assembly modification reactions to direct the partitioning of supramolecular complexes between phases. The system is composed of a self-assembled tetrazine-edged FeII8L12 cube and a maleimide-functionalized FeII4L6 tetrahedron. Norbornadiene (NBD) functions as the stimulus that triggers the cascade, beginning with the inverse-electron-demand Diels–Alder reaction of NBD with the tetrazine moieties of the cube. This reaction generates cyclopentadiene as a transient by-product, acting as a relay signal that subsequently undergoes a Diels–Alder reaction with the maleimide-functionalized tetrahedron. Cyclooctyne can selectively inhibit the cascade by outcompeting NBD as the initial trigger. Initiating the cascade with 2-octadecyl NBD leads to selective alkylation of the tetrahedron upon cascade completion. The increased lipophilicity of the C18-tagged tetrahedron drives this complex into a non-polar phase, allowing its isolation from the initially inseparable mixture of complexes