Cloning of the Extracellular Acid Esterase Gene from Acidophilic Bacterium, Acidocella facilis

An acidophilic heterotrophic bacterium, Acidocella facilis sp. AIU409 produces an extracellular acid esterase when grown in a medium containing sorbitan mono ester, Tween 80. The estA gene encoding for the acid esterase was isolated from the genomic library of A. facilis AIU409, cloned into Escherichia coli MV1184, and the nucleotide sequence of the gene was determined. The structural gene of estA was found to be 1881bp. The open reading frame of estA encodes 627 amino acid residues (calculated molecular mass, 64,140 daltons). A rho-independent terminator was present just downstream of the termination codon, TGA. The deduced N-terminal amino acid showed that the presursor of the acid esterase had a signal peptide composed of 23 amino acids and a consensus sequence of lipase, G-X-S-X-S. The molecular mass excluding the signal peptide calculated from the deduced amino acid sequence if the acid esterase is 61,846. This is lower than the molecular mass, 64kDa estimated by gel electrophoresis. The predicated amino acid sequence of the acid esterase has high similarity to the acyltransferase from Aeromonas hydrophila and the lipase from Xenorhadbus luminescens.好酸性従属栄養細菌AcidocellafacilisAIU409株は，基質としてソルビタンモノエステルであるTweenを含む培地中で培養された時に，菌体外に熱安定性の高い酸性エステラーゼを生産する．エステラーゼをコードする遺伝子（estA）をA.facilisAIU409株のゲノムライブラリーから単離し，大腸菌MV1184にクローニングし，その遺伝子の全塩基配列を決定した．その結果，estAの構造遺伝子が，1881塩基対であることが明らかになった．酸性エステラーゼ遺伝子のオープンリーディングフレーム（ORF）は，627アミノ酸残基（計算された分子量は64,140ダルトン）をコードしていた．ロー因子非依存性の転写終結シグナルが終止コドンであるTGAのすぐ下流に存在していた．そのＮ末端予想アミノ酸配列より，酸性エステラーゼの前駆体は，Ｎ末端に23個のアミノ酸残基から成るシグナルペプチドを有していた．また，リパーゼのコンセンサス配列であるG-X-S-X-Sの配列が存在することが明らかとなった．酸性エステラーゼの予想アミノ酸配列から計算された分子量は61,486であり，これはSDS-PAGEによって予想されていた分子量より，やや低い値であった．また，Acidocellafacilis酸性エステラーゼの予想アミノ酸配列は，Aeromonashydrophila由来のacyltrans-feraseやXenorhabdusluminescens由来のリパーゼと高い相同性を示した

Unmanned Aerial Vehicle-Based Techniques for Monitoring and Prevention of Invasive Apple Snails (<i>Pomacea canaliculata</i>) in Rice Paddy Fields

The destructive impact of invasive apple snail (Pomacea canaliculata) on young rice seedlings has garnered global attention, particularly in warm regions where rice production occurs. The preventative application of insecticide, particularly in areas with young rice seedlings and water depths exceeding 4 cm, has proven effective in mitigating this damage. In line with this recommendation, our study investigates the efficacy of site-specific drone-based insecticide applications to mitigate snail damage in rice paddies. These site-specific drone applications were strategically executed as directed by a highly accurate prescription map indicating the required insecticide quantity at specific locations. The prescription map was automatically generated through an advanced data processing program that used the aerial images acquired by a Real-Time Kinematic (RTK)-Unmanned Aerial Vehicle (UAV) as the input. Criteria were established to select the treatment locations; a value of below 4 cm from the top 95% percentile in the histogram of ground elevation data was used as a threshold to identify areas with a high-density of snail damage. The results demonstrated reductions in both the rates of rice damage and chemical usage following site-specific drone applications compared with the control fields. The findings in this study contribute to the advancement of effective site-specific pest control in precision agriculture