LNEG - Instituto Nacional de Energia e Geologia, IP, Unidade de Bioenergia, Estrada do Paço do Lumiar, 22, 1649-038 Lisboa, Portugal.
N Biotechnol. 2014 Jan 25;31(1):73-9. doi: 10.1016/j.nbt.2013.08.007. Epub 2013 Sep 4.
Biodesulfurization (BDS) aims at the removal of recalcitrant sulfur from fossil fuels at mild operating conditions with the aid of microorganisms. These microorganisms can remove sulfur from dibenzothiphene (DBT), a model compound, or other polycyclic aromatic used as sulfur source, making BDS an easy and environmental friendly process. Gordonia alkanivorans strain 1B has been described as a desulfurizing bacterium, able to desulfurize DBT to 2-hydroxybiphenyl (2-HBP), the final product of the 4S pathway, using d-glucose as carbon source. However, both cell growth and desulfurization can be largely affected by the nutrient composition of the growth medium, due to cofactor requirements of many enzymes involved in the BDS biochemical pathway. In this study, the main goal was to investigate the influence of several sugars, as carbon source, on the growth and DBT desulfurization ability of G. alkanivorans strain 1B. The results of desulfurization tests showed that the lowest values for the growth rate (0.025 hour(-1)) and for the overall 2-HBP production rate (1.80 μm/hour) by the strain 1B were obtained in glucose grown cultures. When using sucrose, the growth rate increase exhibited by strain 1B led to a higher biomass productivity, which induced a slightly increase in the 2-HBP production rate (1.91 μm/hour), conversely in terms of 2-HBP specific production rate (q2-HBP) the value obtained was markedly lower (0.718 μmol/g/hour in sucrose versus 1.22 μmol/g/hour in glucose). When a mixture of glucose and fructose was used as carbon source, strain 1B reached a value of q2-HBP=1.90 μmol/g/hour, close to that in fructose (q2-HBP=2.12 μmol/g/hour). The highest values for both cell growth (μ=0.091 hour(-1)) and 2-HPB production (9.29μm/hour) were obtained when strain 1B was desulfurizing DBT in the presence of fructose as the only carbon source, indicating a fructophilic behaviour by this bacterium. This fact is in agreement with the highest value of biomass productivity by strain 1B be in fructose, which resulted in a higher amount cells fulfilling the DBT-desulfurization. The greater number of functional cells conducted to a more effectiveness BDS process by strain 1B, as they attained a q2-HBP about 74% higher than in glucose grown cultures. Moreover, this significant BDS enhancement can better be observed in terms of the overall 2-HBP production rate, which increased over 5-fold, from 1.80 μm/hour (in glucose) to 9.29 μm/hour (in fructose).
生物脱硫（BDS）旨在在温和的操作条件下，借助微生物从化石燃料中去除顽固的硫。这些微生物可以从二苯并噻吩（DBT）中去除硫，DBT 是一种模型化合物，或其他用作硫源的多环芳烃，使 BDS 成为一种简单且环保的工艺。戈登氏菌属 1B 菌株已被描述为一种脱硫细菌，能够使用 d-葡萄糖作为碳源，将 DBT 脱硫转化为 2-羟基联苯（2-HBP），这是 4S 途径的最终产物。然而，由于 BDS 生化途径中许多酶的辅酶要求，细胞生长和脱硫都可能受到生长培养基营养成分的极大影响。在这项研究中，主要目标是研究几种糖作为碳源对戈登氏菌属 1B 菌株生长和 DBT 脱硫能力的影响。脱硫试验的结果表明，在葡萄糖培养物中，菌株 1B 的生长速率（0.025 小时（-1））和总 2-HBP 生产速率（1.80 μm/小时）的最低值。当使用蔗糖时，菌株 1B 表现出的生长速率增加导致生物量生产率更高，这导致 2-HBP 生产速率略有增加（1.91 μm/小时），相反，在 2-HBP 比生产速率（q2-HBP）方面，获得的值明显较低（在蔗糖中为 0.718 μmol/g/hour，在葡萄糖中为 1.22 μmol/g/hour）。当使用葡萄糖和果糖的混合物作为碳源时，菌株 1B 达到 q2-HBP=1.90 μmol/g/hour 的值，接近果糖中的值（q2-HBP=2.12 μmol/g/hour）。当菌株 1B 在果糖作为唯一碳源的存在下脱硫时，细胞生长（μ=0.091 小时（-1））和 2-HBP 生产（9.29 μm/小时）都获得了最高值，表明该细菌具有果糖嗜性。这一事实与菌株 1B 在果糖中具有最高的生物量生产率值是一致的，这导致了更多满足 DBT 脱硫的细胞。更多功能细胞的存在使菌株 1B 的 BDS 过程更加有效，因为它们的 q2-HBP 比在葡萄糖培养物中高约 74%。此外，从整体 2-HBP 生产速率来看，这种显著的 BDS 增强效果更为明显，从 1.80 μm/小时（在葡萄糖中）增加到 9.29 μm/小时（在果糖中），增加了超过 5 倍。
