Inhibition of polysaccharide synthesis by the sinR orthologue PGN_0088 is indirectly associated with the penetration of Porphyromonas gingivalis biofilms by macrolide antibiotics

How Porphyromonas gingivalis Navigate the Map: The Effect of Surface Topography on the Adhesion of Porphyromonas gingivalis on Biomaterials

The main purpose of this study is to develop an understanding of how Porphyromonas gingivalis responds to subperiosteal implant surface topography. A literature review was drawn from various electronic databases from 2000 to 2021. The two main keywords used were “Porphyromonas gingivalis” and “Surface Topography”. We excluded all reviews and or meta-analysis articles, articles not published in English, and articles with no surface characterization process or average surface roughness (Ra) value. A total of 26 selected publications were then included in this study. All research included showed the effect of topography on Porphyromonas gingivalis to various degrees. It was found that topography features such as size and shape affected Porphyromonas gingivalis adhesion to subperiosteal implant materials. In general, a smaller Ra value reduces Porphyromonas gingivalis regardless of the type of materials, with a threshold of 0.3 µm for titanium.

A Two-Step Strategy for the Rapid Enrichment of Nitrosocosmicus-Like Ammonia-Oxidizing Thaumarchaea

Ammonia-oxidizing archaea (AOA) are widely distributed on the earth and play a significant role in the global nitrogen cycle. Although dozens of AOA strains were obtained in the last 13 years, it is still necessary to obtain more AOA strains for the entire exploration of their ecology, physiology, and underlying biochemistry in different environments. In this study, we designed a two-step strategy for the rapid enrichment of Nitrosocosmicus–like AOA from soils. Firstly, combination of kanamycin and ampicillin was chosen as the selective stress for bacteria and quartz sands were used as the attachment of AOA cells during the first step cultivation; only after 40–75 days cultivation, AOA enrichments with abundance >20% were obtained. Secondly, combination of ciprofloxacin and azithromycin was chosen as the selective stress for the following cultivation; it is able to penetrate the biofilms and kill the bacterial cells inside the aggregate, contributing to the AOA enrichments reached high abundances (90%) only after one-time cultivation. Basing on this strategy, three AOA strains were obtained from agricultural soils only after 90–150 days cultivation. Phylogenetic analysis suggested these AOA belong to the soil group I.1b Thaumarchaeota and are closely related to the genus Nitrosocosmicus. In general, AOA enrichment or isolation is very difficult and time-consuming (an average of 2–3 years). Here, we provide a new strategy for the rapid enrichment of high abundance of Nitrosocosmicus-like AOA from soil, which gives a new solution to the AOA enrichment and cultivation in a short period.

Lipoteichoic Acid Inhibits Staphylococcus aureus Biofilm Formation

A biofilm is an aggregate of microorganisms in which cells adhere to biological or non-biological surfaces and is responsible for various infectious diseases. Infections caused by Staphylococcus aureus, including pneumonia, endocarditis, and osteomyelitis, are often associated with colonization and biofilm formation. Although lipoteichoic acid (LTA) is involved in biofilm formation, the specific role of LTA is not clearly understood. In this study, we demonstrated that LTA released from Lactobacillus plantarum could inhibit S. aureus biofilm formation and aggregation without affecting the growth of S. aureus in various in vitro and in vivo models. L. plantarum LTA (Lp.LTA) also inhibited biofilm formation of S. aureus clinical isolates, including a methicillin-resistant strain. Remarkably, Lp.LTA not only interfered with S. aureus biofilm formation, but it also disrupted a pre-formed biofilm. Mechanism studies demonstrated that Lp.LTA inhibited expression of the ica-operon, which is responsible for the production of poly-N-acetylglucosamine, a key molecule required for S. aureus biofilm development. Lp.LTA increased the release of autoinducer-2 from S. aureus, which contributed to the inhibition of S. aureus biofilm formation. Moreover, Lp.LTA treatment enhanced susceptibility of the biofilm to various antibiotics and to macrophages. Interestingly, Lp.LTA without D-alanine moieties was not able to inhibit biofilm formation by S. aureus. In conclusion, the present study suggests that LTA can inhibit S. aureus biofilm formation, and therefore could be applied for preventing and/or treating infectious diseases caused by S. aureus biofilms.