The demand for rare earth elements has increased dramatically in recent years because of their numerous industrial applications, and considerable research efforts have consequently been directed toward recycling these materials. The accumulation of metals in microorganisms is a low-cost and environmentally friendly method for the recovery of metals present in the environment at low levels. Numerous metals, including rare earth elements, can be readily dissolved in aqueous acid, but the efficiency of metal biosorption is usually decreased under the acidic conditions. In this report, we have investigated the use of the sulfothermophilic red alga Galdieria sulphuraria for the recovery of metals, with particular emphasis on the recovery of rare earth metals. Of the five different growth conditions investigated where G. sulphuraria could undergo an adaptation process, Nd(III), Dy(III), and Cu(II) were efficiently recovered from a solution containing a mixture of different metals under semi-anaerobic heterotrophic condition at a pH of 2.5. G. sulphuraria also recovered Nd(III), Dy(III), La(III), and Cu(II) with greater than 90% efficiency at a concentration of 0.5 ppm. The efficiency remained unchanged at pH values in the range of 1.5-2.5. Furthermore, at pH values in the range of 1.0-1.5, the lanthanoid ions were collected much more efficiently into the cell fractions than Cu(II) and therefore successfully separated from the Cu(II) dissolved in the aqueous acid. Microscope observation of the cells using alizarin red suggested that the metals were accumulating inside of the cells. Experiments using dead cells suggested that this phenomenon was a biological process involving specific activities within the cells.

The demand for precious metals has increased in recent years. However, low concentrations of precious metals dissolved in wastewater are yet to be recovered because of high operation costs and technical problems. The unicellular red alga, Galdieria sulphuraria, efficiently absorbs precious metals through biosorption. In this study, over 90% of gold and palladium could be selectively recovered from aqua regia-based metal wastewater by using G. sulphuraria. These metals were eluted from the cells into ammonium solutions containing 0.2M ammonium salts without other contaminating metals. The use of G. sulphuraria is an eco-friendly and cost-effective way of recovering low concentrations of gold and palladium discarded in metal wastewater.

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田口 明美 1) 柴 光年 2) 沢田ひとみ 1) 早田 篤子 1)桑原竹一郎 1) 渋谷 潔 3) 中谷 行雄 4) 中島 崇裕 5) 吉野 一郎 5) 藤澤 武彦 1)5) 目的：肺がん検診喀痰細胞診では，肺癌のみならず肺以外の癌が発見されている．喀痰集検から発見され た頭頸部扁平上皮癌(HNSCC)の細胞像を解析し，肺扁平上皮癌(LSCC)と比較検討を行った． 方法：1995-2008 年の喀痰集検で病変部位が確定している HNSCC 39 例を対象に臨床学的検討を行い， ま た重複癌と細胞学的検討不能例を除く 31 例で，粘液融解法による蓄痰標本 1 枚に出現した異型扁平上皮細 胞(ASC)および癌細胞における異型度・形状・染色性・変性について，同集検で発見された LSCC と比較 検討した． 成績：喀痰集検が契機で発見された癌の 17.2％(40 例)は HNSCC で，声門癌は 88.9％がⅠ期癌であった． 細胞像では，声門癌で OG 好性多稜形 ASC の出現比率が高く，下咽頭癌・声門上癌は LG 好性円形 ASC が 優勢であった(p＜0.01) ．また HNSCC は LSCC より細胞変性の程度が軽度であった(p＜0.01) ． 結論：声門癌はⅠ期癌が高率で，喀痰細胞診による早期発見が期待された．また ASC の形態学的パターン 解析は，HNSCC と LSCC の鑑別に有用であり，癌発生部位推定の一助になると考えられた． Key words：Sputum cytology，Head and neck cancer，Lung cancer，Squamous cell carcinoma，Lung cancer mass screening Cytological features of head and neck squamous cell carcinoma detected by mass screening sputum cytology, compared with squamous cell carcinoma of the lung Akemi TAGUCHI 1) , C. T., I.