우리는 솔수염하늘소(Monochamus alternatus) 장에 존재하는 공생미생물들을 분리하였다. 그중 다양한 식물 들을 대상으로 성장 촉진 효과가 보고된 세균을 단일배양 분리하였다. 이 세균은 16S rRNA sequencing을 통하여 Enterobacter roggenkampii로 동정되었다. 우리는 분리된 E. roggenkampii에 대하여 genomic sequencing을 수행하 였고 유전학적 특성을 확인하였다. 우리는 E. roggenkampii가 식물의 성장을 촉진할 수 있는 다양한 유전자들을 가지고 있는 것을 확인하였고 그 중 IAA-Asp hydrolase 유전자를 가지고 있음을 알 수 있었다. 동시에, 분리된 E. roggenkampii와 같은 속의 세균을 대상으로 다양한 API kit와 기질 첨가 배지를 이용하여 생화학적 특성을 비교하였다. 향후 IAA-Asp 가수분해효소를 생산하는 잠재적인 식물 생장 촉진 비료 미생물로 등록하여 다양한 작물을 대상으로 생장 촉진 효과를 확인할 것이다.

This study investigates the impact of Bursaphelenchus xylophilus infection on the gut bacterial communities of the pine sawyer beetle, Monochamus alternatus, with a distinction between male and female individuals. Utilizing specific primers, we determined the infection status and analyzed the bacterial composition across different taxonomic levels. Regardless of infection status or sex, Proteobacteria and Firmicutes were found to dominate the phylum level, with significant contributions from Actinobacteria and Bacteroidetes. At the class level, Bacilli, Gammaproteobacteria, Alphaproteobacteria, and Actinobacteria emerged as prevalent groups. Meanwhile, the genus level was characterized by a high abundance of Lactobacillus, Rickettsia, Bacillus, and Rahnella. Our analysis of alpha diversity metrics, including Observed Species, Shannon Index, Inverse Simpson Index, and Phylogenetic Diversity, revealed no significant differences attributable to B. xylophilus infection; however, notable variations were observed between sexes. Principal Coordinates Analysis and Non-metric Multidimensional Scaling further underscored that the differences in gut bacterial communities were more pronounced between male and female beetles than between infected and uninfected individuals. These findings highlight the influence of host sex over infection status in shaping the gut microbiome of Monochamus alternatus, providing new insights into the complex interactions between host biology, gut microbiota, and pathogen infection.

Gut symbiotic microorganisms of insects are known that play important roles in the digestion, development, survival, and reproduction of host insects, and it is widely accepted that symbionts synthesize essential amino acids or vitamins for host insect among these relationship. More recently, however, it has become increasingly apparent that symbiont's contribution to their host are not limited to nutrition. Actually, these symbionts are frequently observed near an insect's digestive tract. In this study, we isolated and identified gut bacteria of ladybird, Harmonia axyridis, which is a predator and used the factor for biological control of aphids, and was aimed to survey gut bacteria affecting to ladybird's biological or ecological characteristics. We separated the guts of larvae and adults ladybird and cultured them in 4 media, such as NA, skim-milk, CMC and CMA. About 33 isolates including genus Arthrobacter were identified in this study. These were cultured in NA media with several antibiotics. We selected ofloxacin and penicillin that inhibited these bacteria growth in media, and reared ladybirds as prey with aphids treated ofloxacin and penicillin 1000ug/1ml concentration. After that, weight of pupae, larval stage, emergence stage, fecundity and hatching rate were investigated. It was shown that, ofloxacin and penicillin treatment was caused by weightless of pupae, fecundity and delay of larval stage, and the affected hatching rate as well.

From the course of screening of useful enzyme producing microorganism from insect guts, we isolated 9 lipase producing strains and their lipase producing activities were tested. 16S rDNA sequence analysis showed that they were Gram negative bacteria grouped on Serratia sp., Pseudomonas sp., and Burkholderia sp.. Among them, an excellent lipase producing strain, Burkholderia sp. HY-10 identified by 16S rDNA analysis and biochemical methods, was further studied its lipase producing characteristics. It was isolated from a longcorm beetle, Prionus insularis and showed cell density dependent lipase producing activity in the culture media that contained olive oil as a carbon source. Maximum lipase production was achieved in the M9 media containing 0.5% yeast extract and 0.5% olive oil when cultured at 30℃ for 36-42 hrs.

This research focused on the isolation and characterization of the new strains which can be used as microbial resources for auxin production in the agriculture industry. For the isolation of the new microorganism in the gut of Larimichthys polyactis, a marine agar medium was used and 3 colonies were isolated. Through the 16S-based ID service, isolated strains were identified as 1 strain of Niallia circulans and 3 strains of Proteus mirabilis. Verifying the agriculture industrial values of these isolated strains, the productivity of auxin and activity of various enzymes such as amylase, lipase, and protease were confirmed. As a result, isolated 3 strains showed auxin activity and only protease activities which means the possibility of applying them to the production of effective microorganisms in the agriculture industry.

Grapefruit extract rich in functional substances adjusting pH 5.0 and adding sucrose (final concentration, 2%) was fermented by Leuconostoc mesenteroides CJNU 0147 strain, consequently prepared a fermented grapefruit extract containing dextran. As a result of analyzing the growth inhibitory effect on gut harmful bacterium Clostridium difficile strain using the prepared fermented grapefruit extract, the viable cell count was significantly reduced (p<0.05 vs. control for 0.5 brix as a final concentration; p<0.001 vs. control for 1.0 brix). On the other hand, the proliferative ability of the extract for Bifidobacterium breve strain, which is one of the species of the genus Bifidobacterium well known as human gut beneficial bacteria, was confirmed (p<0.001 vs. control for both 0.5 and 1.0 brix). These results indicate fermented grapefruit extract with Leu. mesenteroides CJNU 0147 strain inhibits the growth of gut harmful bacterium C. difficile and promotes the proliferation of beneficial bacterium B. breve and is expected to be used as a functional food material for gut health.

Ginseng, the root of the Panax ginseng, has been widely used as a traditional herbal medicine in Korea, China, and Japan for thousands of years. Now ginseng has become popular as functional health food and natural medicine and it is one of the bestselling natural products in the world. Gut microbiota has been found to play an important role in the metabolism and pharmacological action of orally administered ginseng. Recent animal and clinical studies have shown that compound K (20-O -beta-D-glucopyranosyl-20(S)-protopanaxadiol, CK) is the major ginsenoside metabolite deriving from gut microbiota-induced biotransformation and is more efficiently absorbed into the systemic circulation than its parent ginsenosides. Since ginsenoside metabolism varies between individuals depending on the population of gut microbiota, much attention paid to the transformation of major ginsenosides into more pharmacologically active ginsenosides using diverse methods including heating, acid hydrolysis, microbial conversion, and enzymatic treatment. Recently, in food and drug industry and academia, the development of fermented ginseng products using probiotic bacteria is being intensively studied due to the potential health benefits of ginsenoside metabolites and probiotics. This review summarizes recent studies on the metabolism of ginsenoside by gut microbiota and biotransformation of ginsenoside using lactic acid bacteria and their enzymes.

The culture supernatant of Lactobacillus casei CJNU 0588 was prepared from a culture incubated in whey broth (10%, w/v). The culture supernatant stimulated the growth of Bifidobacterium longum subsp. infantis KCTC 3127 and Lactobacillus acidophilus KCTC 3145 which are recognized as human gut beneficial bacteria, whereas inhibited that of Clostridium difficile KCTC 5009 as a gut pathogenic bacterium and Escherichia coli JM109. In co-culture test, L. casei CJNU 0588 cells slightly stimulated the growth of B. longum subsp. infantis KCTC 3127 and L. acidophilus KCTC 3145 but mildly inhibited that of C. difficile KCTC 5009 and E. coli JM109. Therefore L. casei CJNU 0588 strain might positively function to gut microbiota and can be used for gut health-promoting probiotics.

In Japan, milk and food companies have recently developed many functional yogurts using selected probiotic lactic acid bacteria (LAB) and Bifidobacterium strains. In 1991, the FOSHU (foods for specified health uses) system began instituted by the Ministry of Health, Labor and Welfare. In 2010, approximately 1,000 commercially available items were labeled as FOSHU products that are specially given brands showing good health effects for humans. Japanese commercial yogurts are classified into three type categories: fermented using selected probiotics, functional components added, and standard types. Many functions are considered in the selection of probiotics including competitive adhesion exclusion of enteritic pathogens, cholesterol lowering effects, and positive immuno-modulatory effects. Adhesion to the human intestine is one of the most important characteristics of probiotic LAB and bifidobacteria. Our new screening system for adhesive activity involves a combination of three methods: the rat colonic mucin-micro plate assay, the Carnoy’s histochemical staining method, and the carbohydrate probe binding assay. Recently, we developed a new screening assay using the BIACORE biosensor chip coated with human colon mucin (HCM). We found new LAB strains that recognize and specifically bind to the human ABO blood type antigens. We named these “blood type LAB”. We identified the molecular LAB binding mechanism occurring in the human intestine through unique adhesin molecules that are expressed on the bacterial cell surface as lectin-like proteins. Bacteria with strong adhesion ability improve gastrointestinal health by continuous proliferation in the intestine; and increase the chance of intake into the Peyer’s patches through M-cells that inhibit allergies because of LAB immune-stimulating activity. The future Japanese food market will contain superior functional yogurts containing adhesive effective probiotic LAB and bifidobacteria that are expected to be developed using our proposed mass screening system shown here.