Foreword

Microbes such as bacteria and fungi are widely present in the environment. Some environmental microbes cause infections and food poisoning. Therefore the control of pathogenic microbes present in the environment is important for pharmaceutical science, medicine, and public health. To control pathogenic microbes, it is necessary to understand their biological characteristics. Furthermore, this knowledge of their characteristics should be used to guide development of new preventive and therapeutic methods. Disinfection methods, sterilization methods, vaccines, and antibiotics have long been developed for the control of environmental microbes. However, infectious diseases caused by environmental microbes are particularly problematic in developing countries. The current topics section, which comprises six reviews, introduces research challenges regarding surveillance of environmental microbes as well as prevention and treatment of diseases caused by these organisms, including new technologies. The reviews will be of special interest to scientists working on the development of new strategies for drug discovery. Pharmacists should clearly understand the nature of environmental microbes, which can be friends and/or enemies.

For drug discovery, it is necessary to evaluate the efficacy and toxicity of candidate compounds in animal research. In general, mammals such as mice and rats are used, but experiments involving large numbers of these animals are difficult due to cost and ethical considerations. Dr. Yasuhiko Matsumoto contributes the first review, “Facilitating Drug Discovery in Human Disease Models Using Insects.” In this review, Dr. Matsumoto proposes the use of insects as experimental animals in drug discovery, to resolve many problems involved in the use of mammalian animals. There are several benefits from the use of insects as in vivo evaluation systems for identification of drug candidates.

Lactic acid bacteria and Bifidobacterium are often used to produce functional foods. Yogurts produced using lactic acid bacteria are thought to contribute to human health; however, the effective compounds in these yogurts are unclear. The second review is “Prevention of Atherosclerosis by the Induction of Microbial Polyamine Production in the Intestinal Lumen” by Dr. Mitsuharu Matsumoto. In this review, Dr. Matsumoto proposes that the presence of Bifidobacterium and arginine increase the concentration of polyamines in the intestine, and that these elevated polyamine levels contribute to prevention of atherosclerosis. Polyamines are small molecules that exist in the body, and can be synthesized in most organisms from bacteria to humans; these molecules reportedly contribute to an extended lifespan. This review outlines the important discovery that bacteria in the human intestine produce polyamines and contribute to human health.

Vaccines have saved humans from many infectious diseases. Vaccine development will continue to contribute to the treatment of infectious diseases, but there remain many infectious diseases for which vaccines are difficult to develop. Dr. Keigo Ueno et al. contributed the third review, “Vaccines and Protective Immune Memory against Cryptococcosis.” In this review, Dr. Ueno introduces the history of vaccine development against pathogenic fungi, Cryptococcus species, and outlines recent studies regarding immune cell induction by cryptococcal vaccines. This information is highly beneficial for the development of effective vaccination strategies.

Toxicity of candidate compounds often hinders drug development, and it is difficult to develop compounds with high specificity for target cells. Dr. Javier Pizarro-Bauerle and Dr. Hiroki Ando contributed the fourth review, “Engineered Bacteriophages for Practical Applications.” Bacteriophages, which are viruses that infect bacteria, exhibit high degrees of host cell specificity. Dr. Pizarro-Bauerle and Dr. Ando propose that artificially engineered bacteriophages could be useful for fields such as phage therapy, animal industry, and agricultural settings. New technology to generate artificially engineered phages will be a landmark for drug discovery.

Bacillus cereus is a bacterium that is widespread in the environment and causes food poisoning. B. cereus also produces a toxin known as sphingomyelinase, which causes systemic disease. Dr. Masataka Oda et al. contributed the fifth review, “Role of Sphingomyelinase in the Pathogenesis of Bacillus cereus Infection.” This review outlines the regulatory mechanisms involved in the production of B. cereus sphingomyelinase. This knowledge will help to develop new methods for prevention of B. cereus infection.

In the near future, humans will remain in the space environment for extended periods of time. An understanding of the space environment is very important for healthy living while residing in space. Dr. Tomoaki Ichijo et al. contributed the sixth review, “Microbial Monitoring in the International Space Station and Its Application on Earth.” In this review, Dr. Ichijo et al. outlined surveys of environmental microbes in the International Space Station module known as Kibo. Establishment of a culture-free method for monitoring environmental microbes in the International Space Station is highly important, because the majority of these microbes are difficult to culture. The survey data will provide beneficial basic information regarding the control of environmental microbes in space.

These reviews provide beneficial insights for controlling environmental pathogenic microbes by a variety of new approaches. The editor of this Current Topics thanks all of the authors for their important contributions.