Kruppa Oscar, Czermak Peter
Institute of Bioprocess Engineering and Pharmaceutical Technology, University of Applied Sciences Mittelhessen, 35390 Giessen, Germany.
Faculty of Biology and Chemistry, Justus-Liebig University of Giessen, 35390 Giessen, Germany.
Microorganisms. 2022 Apr 12;10(4):801. doi: 10.3390/microorganisms10040801.
Planctomycetes such as offer a promising source of bioactive molecules, particularly when they switch from planktonic to sessile growth, but little is known about the corresponding biosynthetic gene clusters and how they are activated. We therefore screened for factors that promote sessile growth and biofilm formation to enable the cultivation of in a fixed-bed reactor. We carried out screening in microtiter plates focusing on biofilm formation and changes in optical density in response to various C:N ratios, metal ions, and oxidative stress. We used MTT assays and crystal violet staining to quantify biofilm formation. Positive factors were then validated in a fixed-bed bioreactor. The initial screen showed that D1ASO medium supplemented with NHCl to achieve a C:N ratio of 5.7:1, as well as 50 µM FeSO or CuSO, increased the biofilm formation relative to the control medium. Exposure to HO did not affect cell viability but stimulated biofilm formation. However, the same results were not replicated in the fixed-bed bioreactor, probably reflecting conditions that are unique to this environment such as the controlled pH and more vigorous aeration. Although we were able to cultivate in a fixed-bed bioreactor using a chemically defined medium, the factors that stimulate biofilm formation and inhibit planktonic growth were only identified in microtiter plates and further evaluation is required to establish optimal growth conditions in the bioreactor system.
诸如浮霉菌门细菌之类的微生物提供了一个有前景的生物活性分子来源，尤其是当它们从浮游生长转变为固着生长时，但对于相应的生物合成基因簇以及它们如何被激活却知之甚少。因此，我们筛选了促进固着生长和生物膜形成的因素，以便能够在固定床反应器中培养浮霉菌门细菌。我们在微孔板中进行筛选，重点关注生物膜形成以及响应各种碳氮比、金属离子和氧化应激时的光密度变化。我们使用MTT分析和结晶紫染色来量化生物膜形成。然后在固定床生物反应器中验证阳性因素。初步筛选表明，添加氯化铵以达到碳氮比为5.7:1的D1ASO培养基，以及50 μM硫酸亚铁或硫酸铜，相对于对照培养基增加了生物膜形成。暴露于过氧化氢不影响细胞活力，但刺激了生物膜形成。然而，相同的结果在固定床生物反应器中并未重现，这可能反映了该环境特有的条件，如受控的pH值和更剧烈的通气。尽管我们能够使用化学限定培养基在固定床生物反应器中培养浮霉菌门细菌，但刺激生物膜形成和抑制浮游生长的因素仅在微孔板中得到确定，还需要进一步评估以确定生物反应器系统中的最佳生长条件。
