|Abstract: ||摘要:本計劃第三年主要工作是比較不同微生物單獨或共存時的疏水值測定及在glass、polyester、polystyrene、teflon、stainless steel及Zn-ionomer與Na-ionomer等不同材質上的附著能力,顯示細菌於飢餓時其兩種溶劑疏水值無一定趨勢。酵母菌之溶劑疏水值以Rhodotorula rubra > Candida guilliermondii,但與Vibrio alginolyticus HT01共存則增加C. guilliermondii之疏水值,而對 R. rubra則呈不一致結果。分別將細菌及酵母菌置於循環系統測其菌體疏水值的變化,細菌之xylene疏水值隨時間微上升或微降,但hexadecane則下降。兩種酵母菌在72小時內其疏水值變化類似細菌之趨勢。混合細菌及酵母菌於流動的海水中測試其疏水值大致隨時間增加而下降。比較三種微生物菌株於玻璃及塑膠材質附著能力皆以V. alginolyticus HT01 > C. guilliermondii > R. rubra。細菌與C. guilliermondii共存時增加細菌初期附著於玻璃及塑膠材質上的菌數,但在36小時後則呈穩定或抑制的現象;而添加R. rubra在48小時內對玻璃及塑膠材質上會增加細菌的附著菌數。細菌對C. guilliermondii在玻璃及塑膠材質附著上亦有先增後減的情形,但對R. rubra則有強烈的抑制效果。以polyester做控制組並與其他材質比較其不同的材質表面對菌株附著的影響,結果顯示Zn-ionomer、teflon及stainless steel等材質有助於細菌的附著,但Na-ionomer及polystyrene材質在24小時增加附著菌數,爾後則與控制組無明顯差別。同樣將R. rubra與細菌混合後與控制組比較,Na-ionomer、teflon 及stainless steel等材質吸附較多的細菌,而Zn-ionomer及polystyrene材質則與控制組無明顯差別。電顯掃描顯示飢餓細菌由桿形逐漸形成圓形,飢餓細胞附著於材質表面時,菌體表面黏稠物質之形成與附著時間逐漸發生變化。|
Abstract:A major task in this year's project was to determine the hydrophobicity of different single or mixed microorganisms and their adhesion to substrates including coverglass, polyester, polystyrene, teflon, stainless steel, Zn-ionomer and Na-ionomer. Hydrophobicity of Vibrio alginolyticus HT01 starved cells was found to be slightly increased or relatively unchanged when tested with xylene and decrease when determined with hexadecane. The hydrophobicity of Rhodotorula rubra was higher than that of Candida guilliermondii. The hydrophobicity of C. guilliermondii in coexistence with V. alginolyticus HT01 was increased when determined with hexadecane and decreased with xylene assay. In a 72 h flowing seawater system at a flow rate of 0.38 km/h in a biofilm reactor, bacterial and yeast strains demonstrated a similar trend of decreased hydrophobicity with hexadecane determination and increased hydrophobicity in xylene determination. The adhesion rate of these organisms at the optical flow rate in a biofilm reactor was in the order of V. alginolyticus HT01 > C. guilliermondii > R. rubra. In the presence of yeast cells, bacterial adhesion was increased in the early stage on both cover glass and polyester chips and retained or decreased after 36 h. An enhancement of R. rubra adhesion was achieved in the presence of V. alginolyticus HT01. A similar consequence was found in adhesion of C. guilliermondii on two substrata, however, addition of R. rubra exhibited an inhibition effect. Adhesion of bacteria together with yeast on a variety of substrata was compared with polyester as a control in a flow biofilm reactor system. Test organisms readily adhesion to Zn-ionomer, teflon and stainless steel. A high number of cells of some single and mixed species attached to Na-ionomer and polystyrene within 24 h, and then detached later. In the mixed culture, more bacteria attached to Na-ionomer, teflon and stainless steel whereas there was no difference between the mixed culture and the control group in regard to Zn-ionomer and polystyrene. Scanning electron microscopy revealed bacterial cells gradually changing from rods to spheres during cell starvation. Mucoid substances on the cell surface were produced as cells attached onto substratum surface forming some network of biofilm formation.