Aerobic Oral Bacteria in Healthy Captive Snakes

Cotton swab samples were taken from the ventral surface of the mouth and from the proximal esophagus from 23 captive nonpoisonous snakes. The samples were cultured and investigated for aerobic bacteria. Both the mouth and the esophagus) samples of 6 snakes were negative. When the bacterial isolates of the mouth and the esophagus of the whole snake population were compared, it was found that the flora isolated from both locations were similar. However, when the samples of individual snakes were compared it was found that the same isolates were seldom found in both the mouth and the esophagus. The most common bacteria found were Pseudomonas sp., Alcaligenes-like organisms, Gram-positive rods and Gram-positive cocci belonging to the family Micrococcaceae. Important pathogens were seldom isolated. Salmonella virchow could be found from 2 snakes. The presence of bacteriologically negative samples, great variations in the composition of the flora between individual snakes, and the occurrence of typical environmental bacteria in the oral cavity all suggest that snakes lack a specific autochtonous flora: and the bacteria isolated from the oral cavity may be occasional environmental bacteria. The source of pathogens may be the environment, too.     

细菌的信息交流

细菌与细菌之间的信息交流是通过相互交换一种自动诱导物(autoinducer)的信号分子来实现的.这种信息交换的过程被称为群体感应(quorum system).细菌根据这种特定信号分子浓度的变化来监测环境中其它细菌数量的变化.细菌的群体感应系统分为种内和种间信息交流两大类.细菌间的信息交流涉及到细菌的多种生理功能,如细菌的致病能力等.因此研究细菌间的信息交流有可能找到一条新的防治细菌感染途径.     

乳酸菌作为口服疫苗载体的研究进展

乳酸菌是一类重要的工业菌株,是食品级安全菌。利用乳酸菌作为表达载体制成的口服疫苗安全无毒,乳酸菌口服疫苗通过胃肠粘膜进行抗原呈递,能诱导机体产生有效的免疫应答和免疫耐受。近年来对于乳酸菌口服疫苗的研究成为热点,并在此方面取得了突破性成果。     

细菌的信息交流

细菌与细菌之间的信息交流是通过相互交换一种自动诱导物(autoinducer)的信号分子来实现的。这种信息交换的过程被称为群体感应(quorumsystem)。细菌根据这种特定信号分子浓度的变化来监测环境中其它细菌数量的变化。细菌的群体感应系统分为种内和种间信息交流两大类。细菌间的信息交流涉及到细菌的多种生理功能,如细菌的致病能力等。因此研究细菌间的信息交流有可能找到一条新的防治细菌感染途径。     

乳酸菌用作口服疫苗传递载体的研究

乳酸菌是食品级安全菌,利用乳酸菌为表达载体制成的口服疫苗安全无毒,能诱导机体产生有效的免疫应答和免疫耐受。乳酸菌口服疫苗通过胃肠粘膜进行抗原呈递,使用方便,而且较传统注射途径的免疫效果和依从性好,是理想的疫苗,有广阔的发展前景。     

Antimicrobial Activity of Antrodia camphorata Extracts against Oral Bacteria

Antrodia camphorata (A. camphorata) is a unique, endemic and extremely rare mushroom species native to Taiwan, and both crude extracts of and purified chemical compounds from A. camphorata have been reported to have a variety of significant beneficial effects, such as anti-tumor and anti-inflammatory activity. However, reports on the effects of A. camphorata against dental pathogens have been limited. Oral health is now recognized as important for overall general health, including conditions such as dental caries, periodontal disease and rheumatoid arthritis. Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) are the most common bacteria associated with dental plaque and periodontopathic diseases, respectively. Thus, our study examined the ability of five various crude extracts of A. camphorata to inhibit the growth of dental bacteria and anti-adherence in vitro. Among the extracts, the ethanol, ethyl acetate and chloroform extracts exhibited the lowest MICs against P. gingivalis and S. mutans (MIC = 4∼16 µg/mL). The MIC of the aqueous extract was greater than 2048 µg/mL against both P. gingivalis and S. mutans. In vitro adherence of S. mutans was significantly inhibited by the addition of either the ethyl acetate extract or chloroform extract (MIC = 16∼24 µg/mL), while the ethanol extract (MIC = 32∼64 µg/mL) exhibited moderate inhibitory activity. Based on the result of this study, the ethyl acetate and chloroform extracts of A. camphorata may be good candidates for oral hygiene agents to control dental caries and periodontopathic conditions.     

Oral Bacteria as Potential Probiotics for the Pharyngeal Mucosa

The research described here was aimed at the selection of oral bacteria that displayed properties compatible with their potential use as probiotics for the pharyngeal mucosa. We included in the study 56 bacteria newly isolated from the pharynges of healthy donors, which were identified at the intraspecies level and characterized in vitro for their probiotic potential. The experiments led us to select two potential probiotic bacterial strains (Streptococcus salivarius RS1 and ST3) and to compare them with the prototype oral probiotic S. salivarius strain K12. All three strains efficiently bound to FaDu human epithelial pharyngeal cells and thereby antagonized Streptococcus pyogenes adhesion and growth. All were sensitive to a variety of antibiotics routinely used for the control of upper respiratory tract infections. Immunological in vitro testing on a FaDu layer revealed different responses to RS1, ST3, and K12. RS1 and ST3 modulated NF-κB activation and biased proinflammatory cytokines at baseline and after interleukin-1β (IL-1β) induction. In conclusion, we suggest that the selected commensal streptococci represent potential pharyngeal probiotic candidates. They could display a good degree of adaptation to the host and possess potential immunomodulatory and anti-inflammatory properties.Metagenomics and functional molecular immunology substantiate the interpretation of humans as holobionts, in the sense of functional superorganisms, combining the self and microbes acting in concert to produce phenomena governed by the collective (25, 42). The association between host and symbionts affects the fitness of the holobiont within its environment, and it often governs the physiological homeostasis of the narrow balance between host well being and dysfunction (13, 35).The mechanisms underlying the cross talk between a human host and microbes are only marginally understood. Their elucidation at a molecular level could supply the theoretical bases to develop strategies for preventing or treating several human dysfunctions, such as autoimmune diseases, through the reconstitution of a proper human-microbe mutualism.The probiotic approach, in its widest sense, falls into this context, since it consists of the modification of a human microbiota by exogenous administration of microbial cells (or cell components), aimed at benefiting the host''s health. A most commonly accepted definition comes from FAO/WHO, which states that probiotics are “live microorganisms which when administered in adequate amounts confer a health benefit on the host” (17).So far, probiotics have been most predominantly investigated for and applied to the intestinal tract. Nevertheless, a few applications beyond the gut have proposed the potential beneficial role of probiotics for the stomach (23), vaginal mucosa (36), urinary tract (6), skin (27), and oral cavity (39). With respect to oral probiotics, particularly noticeable are the studies done by J. R. Tagg and coworkers of Streptococcus salivarius strain K12. Tagg and others, in fact, showed that, following oral administration, the bacterial strain K12 can colonize the oral mucosae of infants and adults (20, 34), downregulate the innate immune responses of human epithelial cells (11), and reduce oral volatile sulfur compound levels (8). Strain K12 was also revealed to produce two plasmid-encoded lantibiotic peptides (22, 38) that are active against Streptococcus pyogenes, the main etiological agent of bacterial pharyngitis. These investigations demonstrated the potential effectiveness of the probiotic intervention in the oropharyngeal tract.Encouraged by the promising results obtained in J. R. Tagg''s experiments, in the present study, we screened oral bacteria for their potential use as probiotics in the pharyngeal mucosa. We tested the ability of bacteria, which were newly isolated from the pharynges of healthy volunteers, to adhere to a human pharyngeal cell layer and to antagonize S. pyogenes on two different epithelial cell lines. The study allowed the selection of two bacterial strains, which were further investigated from an immunological point of view for their ability to cross talk with human epithelial cells in vitro.     

Adsorption of Immunoglobulin A onto Oral Bacteria In Vivo

Oral bacteria become coated with immunoglobulin A in human saliva in vivo. This may indicate that the salivary immunoglobulin A possesses antibacterial activity. Some of the immunoglobulin-coated cocci grow in extremely long chains and exhibit synchronous cell division. The long chain phenomenon may result from growth in the presence of salivary antibody specific to antigenic determinants of the bacterial cell walls.     

Diversity in Butane Monooxygenases among Butane-Grown Bacteria

Butane monooxygenases of butane-grown Pseudomonas butanovora, Mycobacterium vaccae JOB5, and an environmental isolate, CF8, were compared at the physiological level. The presence of butane monooxygenases in these bacteria was indicated by the following results. (i) O₂ was required for butane degradation. (ii) 1-Butanol was produced during butane degradation. (iii) Acetylene inhibited both butane oxidation and 1-butanol production. The responses to the known monooxygenase inactivator, ethylene, and inhibitor, allyl thiourea (ATU), discriminated butane degradation among the three bacteria. Ethylene irreversibly inactivated butane oxidation by P. butanovora but not by M. vaccae or CF8. In contrast, butane oxidation by only CF8 was strongly inhibited by ATU. In all three strains of butane-grown bacteria, specific polypeptides were labeled in the presence of [¹⁴C]acetylene. The [¹⁴C]acetylene labeling patterns were different among the three bacteria. Exposure of lactate-grown CF8 and P. butanovora and glucose-grown M. vaccae to butane induced butane oxidation activity as well as the specific acetylene-binding polypeptides. Ammonia was oxidized by all three bacteria. P. butanovora oxidized ammonia to hydroxylamine, while CF8 and M. vaccae produced nitrite. All three bacteria oxidized ethylene to ethylene oxide. Methane oxidation was not detected by any of the bacteria. The results indicate the presence of three distinct butane monooxygenases in butane-grown P. butanovora, M. vaccae, and CF8.     

Bacteria—A link among ecosystem constituents

Microbial ecology has undergone a revolution over the past two decades due to the numerous innovations in techniques, allowing bacteria to be detected more accurately by direct means. Thus, bacterial life can be distinguishedin situ by direct counting under epifluorescence microscopy; automatically counting and sizing by image analyzer equipped with epifluorescence microscopy or by use of flow cytometry; specific radioisotope techniques; and molecular techniques to detect specific taxa. All of these approaches do not require cultivation, which provides a biased view of bacterial communities in nature. Bacteria are abundant in aquatic environments and play important roles as links between dissolved nutrients and the grazers in the food web. The new techniques allow an evaluation of bacterial population dynamics and function in relation to other organisms of higher trophic levels. This mini review aims to show briefly the state-of-the-art in microbial ecology for ecologists concerned with organisms other than microbes, in order to develop further intensive study together with microbial ecologists.     

Communication among oral bacteria.

Human oral bacteria interact with their environment by attaching to surfaces and establishing mixed-species communities. As each bacterial cell attaches, it forms a new surface to which other cells can adhere. Adherence and community development are spatiotemporal; such order requires communication. The discovery of soluble signals, such as autoinducer-2, that may be exchanged within multispecies communities to convey information between organisms has emerged as a new research direction. Direct-contact signals, such as adhesins and receptors, that elicit changes in gene expression after cell-cell contact and biofilm growth are also an active research area. Considering that the majority of oral bacteria are organized in dense three-dimensional biofilms on teeth, confocal microscopy and fluorescently labeled probes provide valuable approaches for investigating the architecture of these organized communities in situ. Oral biofilms are readily accessible to microbiologists and are excellent model systems for studies of microbial communication. One attractive model system is a saliva-coated flowcell with oral bacterial biofilms growing on saliva as the sole nutrient source; an intergeneric mutualism is discussed. Several oral bacterial species are amenable to genetic manipulation for molecular characterization of communication both among bacteria and between bacteria and the host. A successful search for genes critical for mixed-species community organization will be accomplished only when it is conducted with mixed-species communities.