Dissolved organic matter production from herder application and in-situ burning of crude oil at high latitudes: Bioavailable molecular composition patterns and microbial community diversity effects

Chemical herders and in-situ burning (ISB) are designed to mitigate the effects that oil spills may have on the high latitude marine environment. Little information exists on the water solubilization of petroleum residues stemming from chemically herded ISB and whether these bioavailable compounds have measurable impacts on marine biota. In this experiment, we investigated the effects of Siltech OP40 and crude oil ISB on a) petroleum-derived dissolved organic matter (DOM_HC) composition and b) seawater microbial community diversity over 28 days at 4 °C in aquarium-scale mesocosms. Ultra-high resolution mass spectrometry and fluorescence spectroscopy revealed increases in aromaticity over time, with ISB and ISB+OP40 samples having higher % aromatic classes in the initial incubation periods. ISB+OP40 contained a nearly 12-fold increase in the number of DOM_HC formulae relative to those before ISB. 16S rRNA gene sequencing identified differences in microbial alpha diversity between seawater, ISB, OP40, and ISB+OP40. Microbial betadiversity shifts were observed that correlated strongly with aromatic/condensed relative abundance and incubation time. Proteobacteria, specifically from the genera Marinomonas and Perlucidibaca experienced -22 and +24 log₂-fold changes in ISB+OP40 vs. seawater, respectively. These findings provide an important opportunity to advance our understanding of chemical herders and ISB in the high latitude marine environment.

Pythium insidiosum keratitis reported in China, raising the alertness to this fungus-like infection: a case series

Background

The objective of this study is to report typical clinical and laboratory characteristics of three cases of keratitis caused by Pythium insidiosum in China.

Case presentation

Three Chinese patients of Han nationality diagnosed with Pythium keratitis from 2017 to 2019 were included. One 45-year-old female and one 55-year-old male were exposed to river water, and one 51-year-old female was burned by ash in the eyes. All of them are of Han ethnicity. Upon slit-lamp examination, subepithelial and superficial stromal opacities were observed in a reticular pattern. After conventional treatment with antifungal agents, the clinical status worsened and therapeutic penetrating keratoplasty was performed. Unfortunately, enucleation was performed to remove all infected tissue and relieve pain. Pythium insidiosum was identified in culture and confirmed by internal transcribed spacer ribosomal RNA gene sequencing analysis. Following the systemic and local antibiotic regimens, the patients were cured ultimately and no regression of infection was observed.

Conclusions

It is significant for ophthalmologists and microbiologist to be alert to this eye-threatening infection, especially in patients who are resistant to antifungal treatments and with water-related exposure.

Comparison of microbial communities and amino acid metabolites in different traditional fermentation starters used during the fermentation of Hong Qu glutinous rice wine

Hong Qu glutinous rice wine (HQGRW) is produced from glutinous rice with the addition of the traditional fermentation starter Hong Qu (mainly Gutian Hong Qu and Wuyi Hong Qu) has been added. It is unpalatable and rejected by consumers because the bitter and umami tastes are too high. The objective of this study was to compare the dynamics of the microbial communities and amino acids especially those in the different traditional fermentation starters used during HQGRW fermentation, and elucidate the key microbes responsible for amino acids. Three widely-used types of Hong Qu starters were used which can make different bitterness and umami in our previous studies, namely, black Wuyi Hong Qu (WB), red Wuyi Hong Qu (WR), and Gutian Hong Qu (GT). The living dynamics of fungal and bacterial communities during the fermentation were determined by high-throughput sequencing and rRNA gene sequencing technology for the first time. The content of amino acids in the HQGRW were determined by reverse-phase high-performance liquid chromatography analysis. The results showed that there were differences between fungal communities during the fermentation process in Wuyi Hong Qu and Gutian Hong Qu starters and between bacterial communities during the fermentation process in the three types of starters. The amino acid content of the samples showed an increasing trend in each group. The total amino acids, as well as the bitter, sweet, umami, astringent amino acids, in the GT Hong Qu group increased more slowly during fermentation, as comparerd to those in WB and WR groups. Furthermore, Meyerozyma, Saccharomyces, Bacillus, Rhizopus, Pediococcus, Monascus, and Halomonas were strongly positively correlated with the content of bitter and umami amino acids (|r| > 0.6 with FDR adjusted P < 0.05) by Spearman's correlation analysis. To conclude, these findings may contribute to a better understanding of the bitter and umami amino acid production mechanism during traditional fermentation and helpful in improving the taste of HQGRW.