In a previously study, the Bacillus sp. strain IA was successfully isolated with high sensitivity to rice husk biochar (RHB). Moreover, RHB promoted an antibiotic iturin A production by strain IA. In order to develop the biocontrol agent, we attempted to reveal the functions of the RHB in promoting the production of iturin A by strain IA. The promotion effects of growth, sporulation and iturin A production of strain IA by the RHB were explained as follows. First, the manganese ion, released from RHB, promoted the sporulation and iturin A production of strain IA. Second, the silicon dioxide contained in RHB adsorbed the metabolic inhibitor(s) and promoted the iturin A production of strain IA. Finally, the combination of manganese ion and silicon dioxide promoted the growth, sporulation and iturin A production of the Bacillus sp. strain IA. To culture strain IA in the medium combining manganese ion and silicon dioxide, the total cells, spore cells and iturin A production increased 15 times, 10,000 times and 18 times higher than the control medium, respectively.

Bacillus subtilis RB14 produces the lipopeptide antibiotic iturin A by submerged and biofilm fermentation. In this study, we optimized the conditions for iturin A production in a jar fermentor. The maximum yield of iturin A was 932 mg L-1 after 120 h. The surface tension of water decreased from 72.0 to 39.0 mN m(-1) as the concentrations of C-14 iturin A increased, indicating that C-14 iturin A behaves as a surfactant in water. The critical micellar concentration obtained from the intersection of two fitted lines was 1.2 x 10(-4) M. Moreover, the surface tension of water decreased as the length of the alkyl chain of iturin A increased.

The purpose of this study is to isolate the beneficial microorganisms whose growth is promoted in the presence of charcoal materials. We successfully isolated strain IA, whose growth is promoted on an agar plate with charcoal materials, and identified it as a novel strain of the Bacillus sp. The growth of strain IA in the liquid medium was promoted by the addition of both activated charcoal (AC) and rice husk biochar (RHB). Moreover, the sporulation of strain IA in the RHB medium and the antifungal activity of the culture supernatant of the RHB medium were much higher than those with AC. HPLC and MS analyses revealed that strain IA produced an antifungal lipopeptide iturin A, and the yield of iturin A in the RHB medium was 8 times higher than that in the medium without RHB. This is the first paper to describe the positive effect of RHB on microbial metabolisms. (C) Pesticide Science Society of Japan

An inhibitory effect of a traditional Japanese fermented food, natto, was found against plant pathogens such as Rhizoctonia solani and Fusarium oxysporum, and the bacteria which showed inhibition were isolated from the natto. Among isolated bacteria, BC-1 and GAc exhibited a strong antagonistic effect in vitro against plant pathogens on an agar medium. The supernatant of bacterial culture also showed strong activity against R. solani, which meant the antimicrobial substances were produced and secreted into the medium. Both of the bacteria were estimated as Bacillus amyloliquefaciens from a partial sequence of the 16s rRNA gene. High performance liquid chromatography analysis clearly showed the production of the lipopeptide antibiotic iturin A by BC-1 and GAc.

To enhance the production of lipopeptide antibiotic iturin A, nutrient contents of the culture mediums were investigated in both submerged and biofilm fermentations. As a carbon source maltose and as nitrogen source, fish protein was used. In submerged fermentation maltose uptake was found lower (12%) compared to biofilm fermentation (15%) that was associated with higher cellular growth in biofilm. However, requirement of nitrogen (fish protein) concentration was found similar in both submerged and biofilm fermentations. Production of iturin A in submerged fermentation with 12% maltose and 5% fish protein was 4450 mg/L, and in biofilm fermentation it was 5050 mg/L when 15% maltose and 5% fish protein was used.

Bacterial endophytes were found from 6 plant leaves among 35 plant leaves screened. Two of the isolated bacteria showed antagonistic activity against fungal plant pathogens. An isolate named KL1 showed the clear inihibition against plant pathogens, Fusarium oxysporum and Rhizoctonia solani, on PDA as well as TSA plate. Supernatant of the bacterial culture also showed the clear inhibition against the fungal growth on the plate and the antibiotic substance was identified as iturin A by HPLC analysis. KL1 was identified as Bacillus sp. from the 16S rRNA gene analysis. Very thin hyphae of R. solani was miccroscopically observed when the fungus was co-cultivated with KL1.

マウスのダイオキシン受容体型転写因子AhRを酵母内で発現させて機能解析した結果、転写活性化を担う61アミノ酸残基からなる領域を見出した。さらに、この領域を介した転写活性化のコアクティベーターとしてPCAF複合体が関与していることを示唆する結果を示した。

マウスのダイオキシン受容体型転写因子AhRを酵母内で発現させて機能解析した結果、転写活性化を担う61アミノ酸残基からなる領域を見出した。さらに、この領域を介した転写活性化のコアクティベーターとしてPCAF複合体が関与していることを示唆する結果を示した。

Interest in microbial surfactants has been steadily increasing in recent years due to their diversity, mass production possibility, selectivity, performance under extreme conditions and potential applications in environmental protection. In this study two pentose sugars (xylose and arabinose) were investigated for the submerged fermentation (SmF) of Bacillus subtilis in surfactant production medium for bio-surfactant surfactin production. An excellent vegetative growth of B. subtilis (× 10(10) CFU/mL) was observed for xylose and arabinose containing medium which were comparable to glucose supplemented medium. Low growth (× 10(8) CFU/mL) was found when medium was not supplemented with any of the sugars. Surfactin production in xylose, arabinose and glucose containing medium was 2700, 2600 and 2000 mg/L, respectively, whereas, medium without any sugar showed low surfactin (700 mg/L) production. These results clearly indicate the effect of pentose sugars on production of surfactin. Gradual depletion of the xylose and arabinose were confirmed by HPLC analysis during the growth phase of the strain that ultimately produced the surfactin.

バイオディーゼル燃料用ジャトロファ（J. curcas）と観賞用ジャトロファ（J. integerrima）の種子および植物体に含まれる脂肪酸およびフォルボールエステル類の組成を解析した結果、両植物で大きく異なることを明らかにした。

Iturin A is an environmentally safe biocontrol agent produced by Bacillus subtilis as a secondary metabolite. Generally iturin A is produced in conventional submerged fermentation. Recently, B. subtilis has received a huge interest for its nature to develop into biofilm as it shows significantly independent genetic and morphological development in biofilm compared to its planktonic culture. In this study it was attempted to compare the production of iturin A in submerged with that in biofilm fermentation using novel marine fish protein as a medium component. When fish protein was compared with commercially available peptones, it was observed that the microbial growth and iturin A productions were similar to those in the medium containing Polypepton S (originated from soybean) and higher than those in the medium containing Polypepton (originated from casein). Quicker cellular growth and secondary metabolite production was observed in submerged fermentation whereas slower but higher cellular growth and iturin A production was found in biofilm fermentation.

バイオディーゼル燃料用ジャトロファ（J. curcas）と観賞用ジャトロファ（J. integerrima）の種子および植物体に含まれる脂肪酸およびフォルボールエステル類の組成を解析した結果、両植物で大きく異なることを明らかにした。

微生物の培養に用いられるペプトンとして、動物タンパク質であるミルクに由来するものと植物タンパク質であるダイズに由来するものが知られている。第三のタンパク源として海洋性資源に着目し、魚に由来するタンパク質を用い微生物の培養を試みた。その結果、良好な生育が認められたばかりでなく、生産指標として用いた抗生物質生産能としても高いものが観察され有望な資源であることが示された。（英文）

微生物の培養に用いられるペプトンとして、動物タンパク質であるミルクに由来するものと植物タンパク質であるダイズに由来するものが知られている。第三のタンパク源として海洋性資源に着目し、魚に由来するタンパク質を用い微生物の培養を試みた。その結果、良好な生育が認められたばかりでなく、生産指標として用いた抗生物質生産能としても高いものが観察され有望な資源であることが示された。（英文）

The gastrointestinal (GI) tract is home to trillions of microbes. Within the same GI tract, substantial differences in the bacterial species that inhabit the oral cavity and intestinal tract have been noted. While the influence of host environments and nutritional availability in shaping different microbial communities is widely accepted, we hypothesize that the existing microbial flora also plays a role in selecting the bacterial species that are being integrated into the community. In this study, we used cultivable microbial communities isolated from different parts of the GI tract of mice (oral cavity and intestines) as a model system to examine this hypothesis. Microbes from these two areas were harvested and cultured using the same nutritional conditions, which led to two distinct microbial communities, each with about 20 different species as revealed by PCR-based denaturing gradient gel electrophoresis analysis. In vitro community competition assays showed that the two microbial floras exhibited antagonistic interactions toward each other. More interestingly, all the original isolates tested and their closely related species displayed striking community preferences: They persisted when introduced into the bacterial community of the same origin, while their viable count declined more than three orders of magnitude after 4 days of coincubation with the microbial flora of foreign origin. These results suggest that an existing microbial community might impose a selective pressure on incoming foreign bacterial species independent of host selection. The observed inter-flora interactions could contribute to the protective effect of established microbial communities against the integration of foreign bacteria to maintain the stability of the existing communities.

微生物の発酵生産において六炭糖が一般的に用いられている。食糧と競合せず、大量に入手可能な未利用資源としてヘミセルロースを構成するキシロースのような五炭糖が考えられる。しかし、五炭糖を資可できる微生物は限られているため、枯草菌を用いた五炭糖の利用と物質生産を試みた。その結果、良好な生育と有用物質であるサーファクチンの生産が認められた。

微生物の発酵生産において六炭糖が一般的に用いられている。食糧と競合せず、大量に入手可能な未利用資源としてヘミセルロースを構成するキシロースのような五炭糖が考えられる。しかし、五炭糖を資可できる微生物は限られているため、枯草菌を用いた五炭糖の利用と物質生産を試みた。その結果、良好な生育と有用物質であるサーファクチンの生産が認められた。

多くの環境問題を抱える現代社会が、持続可能な社会に変換するために必要な条件について、まとめと考察を行った。先ず、資源の有限性を理解し深く認識することが、省資源のライフスタイルにつながることを指摘した。また、生態系やその一部としての人間社会の永続性は、森林の健全性によりもたらせること、特に豊かな土壌形成が食糧生産と文明の持続性の観点からも重要であることをまとめた。（英文）

多くの環境問題を抱える現代社会が、持続可能な社会に変換するために必要な条件について、まとめと考察を行った。先ず、資源の有限性を理解し深く認識することが、省資源のライフスタイルにつながることを指摘した。また、生態系やその一部としての人間社会の永続性は、森林の健全性によりもたらせること、特に豊かな土壌形成が食糧生産と文明の持続性の観点からも重要であることをまとめた。（英文）

In biofilm fermentation, from the very early moments, surfactin was produced along with the biofilm development in the lipopeptide antibiotic production medium by using Bacillus subtilis. However, almost no iturin A was produced in its first 24 hours of cultivation and the production of iturin A began much later. Volumes of the nutrient medium and available surface area of the biofilm reactors were found to be important with the relative production of these two antibiotics. Production of iturin A was increased from 12 mg to about 50 mg per reactor when the culture size was increased from 5 mL to 20 mL, as the depth of the medium was increased. The production level was saturated thereafter with larger volumes. On the other hand, surfactin production was remained similar, which was about 10 mg per reactor, from all the 5 mL to 80 mL of biofilm culture. Optimized temperature for iturin A and surfactin production was observed at 25 and 37°C, respectively. In the biofilm fermentation, production of surfactin was increased when the incubation temperature was increased within the temperature range of 25 to 37°C, on the other hand, iturin A production was gradually decreased with the increase of the incubation temperature.

Malt residue is a common waste or byproduct from beer industries after brewing and milling of malted barley. In this work, Bacillus subtilis RB14 was used to study the microbial growth and production of secondary metabolites like lipopeptide antibiotic iturin A in the malt residue for its effective recycling. B. subtilis RB14 could grow in submerged fermentation of malt residue and significant growth (10(9) CFU/mL) was observed without any supplementation. In submerged fermentation iturin A production using malt residue was about 170 mg/L, which was found to be higher than its production in No.3 (Polypepton, glucose, KH2PO4, MgSO4·7H2O) medium where production was about 120 mg/L. More than 600 mg/L of iturin A production was observed when malt residue was combinedly used with No.3 medium. This production was significantly higher than their summation of their individual production. However, the growth of B. subtilis in combined medium was found to be similar to that of the submerged fermentation in simple malt residue. Therefore, the remarkable enhancement in production of iturin A in supplemented malt residue was attributed to the nutrients supplied from No.3 medium.

Biofilm fermentation is a newly developed promising technique in fermentation technology. In this study no.3 and no.3S media have been used for the lipopeptide antibiotic iturin A production by Bacillus subtilis RB14. The main component of no.3 and no.3S media is Polypepton and Polypepton S, respectively. B. subtilis RB14 produces thick stable biofilm and high amount of iturin A in no.3S medium. Whereas, impaired biofilm formation and lower iturin A production was observed in no.3 medium. From the analytical information it was observed that the amounts of metal ions, such as K(+), Ca(2+) and Mn(2+), cysteine and cellulose are lower in Polypepton compared to the Polypepton S. To investigate their effect on biofilm formation and iturin A production cysteine, cellulose, K(+), Ca(2+) and Mn(2+) were added respectively into the no.3 medium at similar amount that Polypepton S contains. It was observed that individual addition of K(+), Ca(2+), cysteine and cellulose had no effect on biofilm formation, cellular growth induction or iturin A production. However, when Mn(2+) was supplemented in no.3 medium, biofilm development was restored with an improved production of iturin A. Finally, combined addition of investigated substances into the no.3 medium resulted with highly folded, thick biofilm with high cellular growth and iturin A production compared to the original no.3 medium.

A new solid state fermentation reactor (SSFR) for solid substrate was used for the production of lipopeptide antibiotic iturin A using Bacillus subtilis RB14-CS. Solid state fermentation (SSF) is the technique of cultivation of microorganisms on solid and moist substrates in the absence of free water. SSF has shown much promise in the development of several bioprocesses and products because of their several advantages like absence of free water that allows simplified downstream processing and low cost. SSFR allows agitation of the SSF culture with improved temperature control and air supply. Interestingly, when okara, the widely available waste product from the tofu industries, was used as the solid substrate for the SSFR, no iturin A production was observed. However, without agitation, production of iturin A was observed in the SSFR but the production level remained low. The low production of iturin A was found to be due to the heat generation and excess temperature rise inside the reactor system during the fermentation process. Maintaining the temperature within a range of 25-30°C, production of iturin A was significantly improved in the SSFR. This was comparable to the laboratory scale production, and signifies the potential application of the SSFR for SSF.

Iturin A is a cyclic lipopeptide antibiotic and eight different kinds of iturin A have been reported based on its alkyl side chains. As iturin A is a promising biocontrol agent, total production of iturin A was tried to enhance and comparative production of its homologues was investigated by using different nitrogen and carbon sources. When Polypepton S and defatted soybean meal were used, total production as well as the ratio of the iturin A homologues were similar. However, production of iturin A was relatively lower and also the ratio of the iturin A homologues was different when Polypepton was used, where A2 was decreased and A4 was increased. Production ratio of the iturin A homologues was similar for the carbon sources like maltose, mannitol, sucrose and starch but relative production of iturin A2 was much enhanced compared to A3 when lactose or galactose was used. Interestingly production ratio of A4 was increased and A2 and A3 were decreased when no additional carbon source was used, and similar tendency was observed in the homologue ratio with glucose and fructose. Production of iturin A homologue A6 was significantly increased whereas A2 and A3 were decreased when defatted rapeseed cake was used. Utilization of different amino acids did not show significant differences in their production of the iturin A homologues. Oxygen supply found to be the factor affecting the production of iturin A homologues when it was investigated in a varied culture volume size and shaking speed. A2 found to be increased with increased oxygen supply where the production of A3 was affected inversely.

We have performed analytical studies on the radio frequency (rf) electromagnetic (EM) waves in a ferroelectric cathode with a grid electrode. During operation of the cathode, a trigger voltage induces a very strong field at the vacuum-metal-ferroelectric triple junction, which results in local saturation of the material's dielectric property near the corresponding area. High frequency oscillations generated from the saturation then lead to the formation of standing waves. With the practical geometry and the material property used in the experiments, the oscillation frequency of the lowest mode (TM01) is found to overlap that of the domain oscillation of the ferroelectric material. This provides domains with the possibility of gaining energy from the EM wave through resonance to sustain their oscillation, which is considered to be related with electron emission. The rf pass band was studied by varying the geometry and the material properties of the cathode, and this may lead to optimization of the cathode shape. (C) 2003 American Institute of Physics.

Electron emission from ferroelectric cathodes is observed using two kinds of Pb(Zr,Ti)O-3 (PZT) material in the same cathode geometry. Beam currents are found to follow a three-halves power rule to the diode voltage, which suggests that the beam currents are "space-charge-limited". However, the perveances of the electron guns differ by more than 100%. The difference in "space-charge-limited current" is found to be related to the difference in the frequency characteristics of the materials. This implies that domain oscillation may contribute to the strong electron emission, under our experimental conditions. The experimental results provide a key point, which may lead to a more complete understanding of electron emission from ferroelectric materials.

We report behaviors of microwave amplification obtained from an X-band single-stage traveling wave tube (TWT) amplifier driven by a ferroelectric electron gun. In our experiment, it was observed that the gain of the TWT disappeared when the diode voltage dropped below 300 kV, even if the beam current was still high. This behavior is considered to be associated with the characteristics of ferroelectric emission.

We have studied emission characteristics of a PZT ferroelectric cathode under influence of a strong accelerating field using two kinds of PZT materials, LZT-2 and APC850, with the same cathode geometry. The perveances of the electron guns differ by more than 100%. The difference of the emitted electron is found to be related to the difference of frequency characteristics of the materials, which implies that the electron emission is possibly caused by the local domain oscillation in the close vicinity of vacuum-ferroelectric-metal triple-junction. The experimental results provide a key-point which may lead to a more complete-understanding of electron emission from ferroelectric materials.

We propose a method for emittance measurement of an axisymmetric high-current electron beam confined by a longitudinal magnetic field. In this method, the beam current is measured by a multi-layer Faraday cup to obtain the radial beam current profile using Abel inversion. Based on the theory of a beam in a uniform focusing channel, the transverse electron temperature is uniquely defined by the shape of the current density profile. Therefore, measuring the current density profile enables the determination of the beam emittance. Because the method does not require to use slits, the measurement has been markedly simplified. The method has been adopted to a test beam. The emittance is found to be 20.2pi mm(.)mrad, which basically agrees with that obtained by a slit-slit method.

We propose a method for emittance measurement of a space charge dominated axisymmetric electron beam confined by a longitudinal magnetic field. In this method, the beam current is measured by a multi-layer Faraday's cup to obtain the radial beam current profile through the Able inversion. Based on the theory of beam in a uniform focusing channel, the transverse electron temperature is uniquely defined by the shape of the current density profile. Measuring the current density profile allows a determination of the beam emittance. Because the method does not require using slits, measurement has been remarkably simplified. The method has been adopted to a testing beam. The emittance is found to be 20.2pi mm.mrad, which basically agrees with that from a slit-slit method.

A gene (rpoDA) of Pseudomonas aeruginosa whose gene product has a homologous function and structure with the principal sigma factor of Escherichia coli was cloned and sequenced. The DNA region corresponding to one of the two hybridization signals found in P. aeruginosa DNA with a synthetic oligonucleotide probe (rpoD probe) was shown to be able to complement a temperature sensitive mutation of Escherichia coli rpoD gene. The amino acid sequence deduced from the nucleotide sequence of rpoDA showed an extensive homology with that of the principal sigma factor of E. coli throughout the entire region, which indicates that the two gene products have an essentially identical domain structure. A common basic structure observed among principal sigma factors of different eubacterial strains was proposed. RpoDA protein was identified in the extract of the cell carrying a plasmid clone with the rpoDA gene insert by Western blot analysis.

シデロフォア形成能、リン可溶化能、フィチン可溶化能を指標として、環境微生物をスクリーニングした結果、複数の微生物株が単離された。中でもA-2株は、これらについて最も強い能力を示した。さらに、A-2株は、シロイヌナズナ芽生えの側根数の増加や根毛の増加、地上部の生長促進などを引き起こし、PGPRとしての特徴を示した。A-2株は、紫外線照射下において蛍光を発すること、および、16S rRNA遺伝子の塩基配列から、Pseudomonas fluorescensであることが強く示唆された。一方、A-2株は、植物病原菌Fusarium oxysporumとRhizoctonia solaniの増殖を抑制することができた。

シロイヌナズナ芽生えの側根伸長を促進する土壌微生物A-2株を単離した。16S rRNA遺伝子の塩基配列から、このA-2株はPseudomonas fluorescensであることが示唆された。実際に、この微生物はシデロフォアを形成し、リンとフィチンの可溶化能を有しており、紫外線照射下において蛍光を発した。また、A-2株は、植物病原菌Fusarium oxysporumとRhizoctonia solaniの増殖を抑制することができた。

地球環境の危機的状況が指摘される中、循環型社会への転換という持続可能な文明に向けての解決案も有している。環境問題の根源的原動力について考え、本質的な解決を望むには、その原動力を支える価値観の転換が必要であること、そのためには残された時間の認識、視野の拡大などが重要であることを指摘した。

厨房グリストラップや土壌から油脂を分解できる菌を単離した。これらは実際に高いリパーゼ活性を持っていた。製剤化へ向けて、単離菌の凍結保存を試みた。

非常に高い界面活性能を示すことからバイオサーファクタントが注目されている。産業利用には大量生産が必須であり、そのためには安価な培養基が必要である。未利用資源としての植物性バイオマスの一つである、ヘミセルロースに着目し、その主構成成分であるキシロースとアラビノースを用いて培養を行ったところ、高いサーファクタントの生産が認められ、その原因として糖消費のスピードが抑制され生産期間が長期に亘ったことが示唆された。（英文）

Microbial fuel cells (MFCs) are devices that use microorganisms as biocatalysts to directly convert chemical energy to electricity. MFCs are considered to be useful when used with organic waste treatment processes, because electricity is generated from organic wastes. In this study, MFCs were further used to produce antibiotic substances as well as electroricity, and made it possible to co-produce electricity and an antibiotic substance.

The main components of plant biomass are carbohydrates, a mixture of cellulose, and hemicellulose. When cellulose and hemi-cellulose are hydrolyzed, their constituent sugars, glucose(a six carbon sugar, hence "C6") and xylose(a five carbon sugar, hence,"C5"), are produced respectively. As a method of metabolizing the C5 sugars is required to utilize the biomass effectively, Bacillus subtilis was used to metabolize the C5 sugar. Production of a useful antibiotic as a model compound was employed, and the higher productivity was observed, and the usefulness of C5 sugars were shown.

鉄イオンは、生物の生育にとり必須の成分であるが、土壌環境中に住む微生物にとってもそれは例外ではない。大部分の鉄原子は酸化された状態で存在するため、常に土壌中は鉄欠乏状態である。極微量の鉄イオンを利用するために、多くの生物はシデロフォア-と呼ばれる鉄キレートペプチドを生産する。我々は、植物病原菌を強く抑制し微生物農薬として利用できる菌のスクリーニングをする中で、抗生物質イチュリンと共にバイオサーファクタントであるサーファクチンを同時に生産する新しい枯草菌を見い出した。また、この枯草菌がイト-酸と呼ばれるシドロフォア-(2,3-ジヒドロキシベンゾイルグリシン)を生産しており、この物質の生産も上記遺伝子により制御されていることを見いだした。この遺伝子の物質生産における機能解析を、遺伝子の小型化や生産性の低い類似遺伝子との組換えによりハイブリッド遺伝子の作製を行った。得られた遺伝子を、遺伝子の欠損株である宿主に導入することにより物質生産の比較を行った。その結果、上記リポペプチド性抗生物質やシデロフォア-の生産において、短くなった遺伝子における生産性がいずれの場合も減少したため、遺伝子産物のカルボキシル末端が重要な働きをしていることが示された。また、この遺伝子欠損株の土壌中における定着性を元株と比較したところ、他の拮抗微生物が存在しない滅菌土壌においては、あまり差が認められなかったが、土着の微生物が存在する非滅菌土壌においては、定着率の現象が観察された。従って、リポペプチド性抗生物質やシデロフォア-の生産が、枯草菌が微生物農薬として土壌に定着する際に重要な役割を果たしていることが示唆された。

バイオサーファクタントは、優れた界面活性剤としての機能の他に、安全性が高く生分解性を受けるため、環境保護の点からも重要な物質である。中でもサーファクチンはバイオサーファクタントとしては、表面張力低下能が大きいリポペプチド系界面活性剤として知られている。しかし生産性の低さから実用化には至っていない。我々は、新しいサーファクチン生産菌をスクリーニングし、本物質の生産に関わる遺伝子のクローニングに成功している。この遺伝子(lpa-14)はサーファクチン生産のみならずリポペプチド性抗生物質イチュリンAの生産にも関与している事が別途確認されている。先ず、lpa-14遺伝子の破壊株に対する形質転換を行った。この遺伝子破壊によりこの菌株は両物質の生産能を失っている。その結果、lpa-14遺伝子が保持されている場合は、全ての形質転換体がサーファクチンの生産能を回復した。しかし、その生産性は、lpa-14の隣接領域の有無により大きく異なることが示された。この隣接した領域をlpa-14遺伝子と同時に形質転換するとサーファクチン生産性が約3倍に増加する事を見いだした。この生産性増加に関与する領域を限定するために数種のサブクローンを構築した。これらの遺伝子を用いて同様の形質転換を行いサーファクチンの生産性への影響を調べたところ、lpa-14の下流域の約2kbpが生産性の増強に関与していることが示された。しかし、この領域は抗生物質イチュリンAの生産性には全く影響を示さないことが判明した。従って、この増強機構はサーファクチン特有のものであることが示唆された。部分的ではあるが、本領域の塩基配列の決定を行った所、DNA結合ドメインを持つ読み枠(ORF)が見いだされたため、この生産性増強遺伝子とサーファクチン生合成遺伝子との相互作用が類推された。

磁場の生物に与える影響を調べ、その有効利用を図るために、遺伝子解析の最も進んだ大腸菌を用いてその影響を調べた。地球磁場の10万倍以上という超高磁場を、大腸菌のlambdaファージ溶原株に印加したところファージのプラーク形成能が、超高磁場中では約10倍に増大することが示され、磁場の影響は増殖開始のオン・オフを制御する遺伝子スイッチへの影響であると考えられた。そこで本研究では、より誘導能の高い遺伝子スイッチの探索と、超高磁場による遺伝子スイッチの制御を研究目的とした。超高磁場中において遺伝子発現が誘導される菌株を構築するために、Muファージを用いbeta‐ガラクトシダーゼの構造遺伝子を導入した遺伝子ライブラリーの構築を行った。Muファージは大腸菌の染色体にランダムに挿入され、挿入を受けた遺伝子の発現制御を受けるため、未知の遺伝子の探索とその発現パターンの解析を行うことができる。また、誘導因子として高磁場の他にパルス電場も用い、その特性の比較も試みた。約、1000株についてスクリーニングを行った所、パルス電場に応答する菌株は数株得られたが、明確に磁場により誘導が認められる遺伝子挿入株は発見されていない。しかし、大腸菌自身の増殖は磁場中において明かな影響を受けていることと、二次元ゲル電気泳動の結果から、磁場の有無によって発現の増大したタンパク質や、逆に減少したものが認められた。従って、今後はこれらのタンパク質に焦点を絞って解析を行い、磁場応答遺伝子の解析を行うことが興味深いと考えられる。