Synthesis of the Oligosaccharides of Burkholderia pseudomallei and B. mallei Capsular Polysaccharide and Preliminary Immunological Studies of Their Protein Conjugates.

Efficient strategies were developed for the synthesis of 6-deoxy-d-manno-heptopyranose and its ß-(1 → 3)-linked oligomers as fragments of the common and major capsular polysaccharide, type I O-PS, of Burkholderia pseudomallei and Burkholderia mallei. The unusual heptose was synthesized from mannose, highlighted by the facile Wittig reaction and anti-Markovnikov hydroboration of the resultant olefin. The difficult ß-mannosidic linkage in the oligosaccharides was achieved in high stereoselectivity by H-bond-mediated aglycone delivery. All of the oligosaccharides were conjugated with the carrier protein CRM197. Preliminary immunological evaluations of the resultant glycoconjugates in mice verified their efficacy to elicit high titers of immunoglobulin G antibodies and robust T-cell-dependent immune responses. It was also found that the trisaccharide conjugates provoked the strongest immune responses, worthy of further in-depth study for vaccine development.

Abundant Cyanobacteria in Autumn Adhering to the Heating, Ventilation, and Air-Conditioning (HVAC) in Shanghai.

Cyanobacteria are ever-present, mainly flourishing in aquatic environments and surviving virtually in other habitats. The microbiota of indoor dust on the pre-filter of heating, ventilation, and air-conditioning (HVAC) systems, which reflect indoor microbial contamination and affect human health, has attracted attention. Contemporary studies on cyanobacteria deposited on the pre-filter of HVAC remain scant. By the culture-independent approach of qPCR and high throughput sequencing technologies, our results documented that the cyanobacterial concentrations were highest in autumn, occurred recurrently, and were about 2.60 and 10.57-fold higher than those in winter and summer. We proposed that aquatic and terrestrial cyanobacteria contributed to the pre-filter of HVAC by airborne transportation produced by wave breaks, bubble bursts, and soil surface by wind force, owing to the evidence that cyanobacteria were commonly detected in airborne particulate matters. The cyanobacteria community structure was characterized in Shanghai, where Chroococcidiopsaceae, norank_cyanobacteriales, Nostocaceae, Paraspirulinaceae, and others dominated the dust on the pre-filter of HVAC. Some detected genera, including Nodularia sp., Pseudanabaena sp., and Leptolyngbya sp., potentially produced cyanobacterial toxins, which need further studying to determine their potential threat to human health. The present work shed new insight into cyanobacteria distribution in the specific environment besides aquatic habitats.

Abundant bacteria and fungi attached to airborne particulates in vegetable plastic greenhouses.

The proliferation of modern vegetable plastic greenhouses (VPGS) supplies more and more vegetables for food all over the world. The airborne bacteria and fungi induce more exposure opportunities for workers toiling in confined plastic greenhouses. Culture-independent approaches by qPCR and high-throughput sequencing technology were used to study the airborne particulates microbiota in typic VPGS in Shandong, a large base of vegetables in China. The result revealed the mean airborne bacteria concentrations reached 1.67 × 103 cells/m3 (PM2.5) and 2.38 × 103 cells/m3 (PM10), and the mean airborne fungal concentrations achieved 1.49 × 102 cells/m3 (PM2.5) and 3.19 × 102 cells/m3 (PM10) in VPGS. The predominant bacteria in VPGS included Ralstonia, Alcanivorax, Pseudomonas, Bacillus, and Acinetobacter. Botrytis, Alternaria, Fusarium, Sporobolomyces, and Cladosporium were frequently detected fungal genera in VPGS. A higher Chao1 of bacteria in PM10 was significantly different from PM2.5 in VPGS. The potential pathogens in VPGS include Raltonia picketti, Acinetobacter lwoffii, Bacillus anthracis, Botrytis cinerea, and Cladosporium sphaerospermum. The network analysis indicated that airborne microbiota was associated with soil microbiota which was affected by anthropologic activities. The predicted gene functions revealed that bacterial function mainly involved metabolism, neurodegenerative diseases, and fungal trophic mode dominated by Pathotroph-Saprotroph in VPGS. These findings unveiled airborne microbiomes in VPGS so that a strategy for improving air quality can be applied to safeguard health and vegetation.

Synthesis of a trisaccharide repeating unit of the O-antigen from Burkholderia anthina and its dimer.

A trisaccharide repeating unit of the O-antigen from Burkholderia anthina, α-L-Rha-(1→2)-α-L-Rha-(1→2)-ß-D-Gal-O(CH2)3NH2 (1), and its dimer, α-L-Rha-(1→2)-α-L-Rha-(1→2)-α-D-Gal-(1→3)-α-L-Rha-(1→2)-α-L-Rha-(1→2)-ß-D-Gal-O(CH2)3NH2 (2), were synthesized via a highly convergent and efficient assembly strategy. Sequential glycosylation of galactosyl acceptor 6 with rhamnosyl thioglycoside 7, followed by condensation of the resulting disaccharide acceptor 9 with rhamnosyl imidate donor 10, gave the title molecule 1 after global deprotection. The title hexasaccharide 2 was assembled in a convergent [2+2+2] manner, in which α-1,2-linked disaccharide 12 was initially obtained by the coupling reaction of disarmed thiorhamnoside acceptor 15 with armed thiogalactoside donor 14. Sequential glycosylation of disaccharide acceptor 9 with thioglycoside donors 12 and 13 afforded the target compound 2 after global deprotection.