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討論
Winkler技術是估算浮游生物系統中細菌呼吸最常用的技術。該技術具有較高的靈敏度（見表2），但其缺點是無法隨時間連續監測氧氣濃度。呼吸通常根據初始和最終氧氣濃度之間的差異計算，假設在孵化期間氧氣呈線性減少。先前的研究已經表明，長期培養過程中氧氣的減少并不總是線性的，但可以表現出不同的模式，如指數衰減或指數增加（Biddanda et al.1994；Pomeroy et al.1994）。此外，盡管靈敏度很高，但通常需要較長的孵育時間來檢測顯著的呼吸速率，特別是在低營養水域中，在那里孵育可長達36小時。這些長時間孵化的主要后果有充分的記錄；這包括細菌數量和活性的變化（見del Giorgio和Cole 1998年的綜述），以及群落組成的變化（Massana等人，2001年；Gattuso等人，2002年）。
表2. 測量浮游生物環境中氧濃度的不同方法
使用氧氣微探針測量細菌呼吸可以解決離散測量中遇到的主要問題之一：在黑暗培養期間監測氧氣減少。在這項研究中進行的27項測量中，只有9項顯示出氧濃度的線性下降，其他的顯示出某種程度上與水的營養狀態相關的趨勢。這種監控有兩個主要優點。首先，通過跟蹤氧濃度與時間的關系，可以檢測到顯著耗氧量的開始。由于采用了保護陰極（Revsbech 1989），氧氣微探針不會消耗氧氣，并且顯示出約0.1μM O2的高精度，該值與在高精度Winkler測量中觀察到的值相似（見表2）。然而，這種高靈敏度被背景噪聲抵消，背景噪聲通常發生在用微探針測量氧氣的過程中。因此，在浮游水域進行氧氣測量時，0.1μM的理論精度實際上降低到0.5μM O2。
第二個優點是，一旦發現顯著的氧氣減少，就可以大大縮短培養時間，從而在記錄足夠的數據點時停止培養。因此，通過最小化瓶子效應和伴隨的群落變化，在盡可能接近初始原位條件的條件下進行測量。
然而，氧微探針的精度不足以測量培養時間短的貧營養水體中的細菌呼吸。對貧營養水體中氧濃度的監測表明，只有在培養過程中細菌活性和生物量增加后，氧微探針才能測量到氧濃度的降低（圖4B）。這清楚地表明，這些水域的呼吸測量仍然存在問題，因為目前還沒有靈敏度足以檢測這些非常低的原位呼吸率的技術。Gattuso等人（2002年）提出了替代技術的應用，這將提供更高的氧敏感性，因此可能大大縮短培養時間，例如使用膜入口離子阱質譜法（Cowie和Lloyd，1999年）來估計呼吸速率。
評論和建議
BGE的測定需要估計細菌產量。這通常是通過使用放射性標記的亮氨酸或胸腺嘧啶核苷測量蛋白質或DNA合成速率來完成的，盡管也可以使用細菌豐度和大小的變化。通過加入放射性示蹤劑來估計細菌產量可以在很短的培養時間內完成，并且被認為是原位率的一個很好的代表。然而，BGE是根據比用于測定細菌產量的時間更長的培養時間內估計的細菌呼吸來計算的。因此，BGE是根據在兩種不同培養條件下估計的兩種代謝過程的速率來計算的，這可能會使其產生偏差（即，在短時間間隔內測量的生產速率可能與更長時間范圍內的呼吸速率不一致）。根據培養期間細菌豐度的變化估算細菌凈產量，以進行呼吸測量，這是一種替代解決方案。通過使用非破壞性方法測量氧氣變化，可以在培養結束時獲得子樣本，以確定細菌的凈生物量。這樣，兩個過程將以相同的時間尺度和相同的孵化條件進行估計。
通過連續監測細菌呼吸測量期間的氧氣變化來縮短培養時間的可能性需要以足夠的精度確定細菌凈生物量的產生。為了達到所需的靈敏度，使用表觀熒光顯微鏡測定細菌數量需要對大量細菌進行計數，并使用多個復制品，特別是在貧營養水域。這將大大增加與測量相關的工作量。流式細胞術可能是測定呼吸培養期間細菌凈生物量的一種替代技術。與表面熒光顯微鏡相比，該技術提供了一種更高靈敏度的細菌數量測量方法（Troussellier等人，1999年；Lemarchand等人，2001年）。此外，流式細胞術可用于在培養開始和結束時估計細胞的生物體積，甚至蛋白質含量（Zubkov等人，1999年），從而更好地計算細菌凈產量，因為在BGE測定的培養過程中，經常報告細菌細胞生物體積的變化（Gattuso等人，2002年）。
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使用氧微電極來研究細菌的呼吸作用以確定浮游細菌的生長速率——摘要
使用氧微電極來研究細菌的呼吸作用以確定浮游細菌的生長速率——材料和程序
