Comparative evaluation of direct plating and most probable number for enumeration of low levels of Listeria monocytogenes in naturally contaminated ice cream products

AbstractA precise and accurate method for enumeration of low level of Listeria monocytogenes in foods is critical to a variety of studies. In this study, paired comparison of most probable number (MPN) and direct plating enumeration of L. monocytogenes was conducted on a total of 1730 outbreak-associated ice cream samples that were naturally contaminated with low level of L. monocytogenes. MPN was performed on all 1730 samples. Direct plating was performed on all samples using the RAPID'L.mono (RLM) agar (1600 samples) and agar Listeria Ottaviani and Agosti (ALOA; 130 samples). Probabilistic analysis with Bayesian inference model was used to compare paired direct plating and MPN estimates of L. monocytogenes in ice cream samples because assumptions implicit in ordinary least squares (OLS) linear regression analyses were not met for such a comparison. The probabilistic analysis revealed good agreement between the MPN and direct plating estimates, and this agreement showed that the MPN schemes and direct plating schemes using ALOA or RLM evaluated in the present study were suitable for enumerating low levels of L. monocytogenes in these ice cream samples. The statistical analysis further revealed that OLS linear regression analyses of direct plating and MPN data did introduce bias that incorrectly characterized systematic differences between estimates from the two methods

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

Isolation, Structure Elucidation, and Antibacterial Activity of Methiosetin, a Tetramic Acid from a Tropical Sooty Mold (<i>Capnodium</i> sp.)

Drug-resistant bacteria continue to make many existing antibiotic classes ineffective. In order to avoid a future epidemic from drug-resistant bacterial infections, new antibiotics with new modes of action are needed. In an antibiotic screening program for new drug leads with new modes of action using antisense <i>Staphylococcus aureus</i> Fitness Test screening, we discovered a new tetramic acid, methiosetin, from a tropical sooty mold, <i>Capnodium</i> sp. The fungus also produced epicorazine A, a known antibiotic. The structure and relative configuration of methiosetin was elucidated by 2D NMR and ESIMS techniques. Methiosetin and epicorazine A showed weak to modest antibacterial activity against <i>S. aureus</i> and <i>Haemophilus influenzae</i>. The isolation, structure elucidation, and antibacterial activity of both compounds are described

Isolation, Structure Elucidation, and Biological Activity of Altersolanol P Using <i>Staphylococcus aureus</i> Fitness Test Based Genome-Wide Screening

Bacteria continue to evade existing antibiotics by acquiring resistance by various mechanisms, leading to loss of antibiotic effectiveness. To avoid an epidemic from infections of incurable drug-resistant bacteria, new antibiotics with new modes of action are desperately needed. Using a genome-wide mechanism of action-guided whole cell screening approach based on antisense <i>Staphylococcus aureus</i> fitness test technology, we report herein the discovery of altersolanol P (<b>1</b>), a new tetrahydroanthraquinone from an unknown fungus from the Hypocreales isolated from forest litter collected in Puerto Rico. The structure was elucidated by high-resolution mass spectrometry and 2D NMR spectroscopy. Relative stereochemistry was established by NOESY correlations, and absolute configuration was deduced by the application of MPA ester-based methodology. Observed ¹H and ¹³C NMR shifts were well aligned with the corresponding chemical shifts predicted by DFT calculations. Altersolanol P exhibited Gram-positive antibacterial activity (MIC range 1–8 μg/mL) and inhibited the growth of Gram-negative <i>Haemophilus influenzae</i> (MIC 2 μg/mL). The isolation, structure elucidation, and antibacterial activity of altersolanol P are described