The microbial biofilms are ubiquitous in nature and represent important biological entities that affect various aspects of human life. As such, they attracted considerable attention during last decades, with the factors affecting the biofilm development being among the frequently studied topics. In our work, the biofilm was cultivated on the surface of polypropylene fibers in a nutrient medium inoculated by the suspension of two unsterile soils. The effects of ionic strength and valence of salt on the amount of the produced biofilm and on composition of biofilm microbial communities were investigated. The effect of valence was significant in some OTUs: Arthrobacter/Pseudarthrobacter/Paenarthrobacter and Bacillus with positive response to monovalent salt (KCl) and Streptomyces, Lysinibacillus, Pseudomonas, and Ensifer with positive response to divalent salt (MgSO₄). The significant preference for a certain concentration of salts was observed in the case of OTUs Agrobacterium, Bacillus (both 100 mM), and Brevundimonas (30 mM). A new quantification method based on measuring of oxidizable organic carbon in biofilm biomass, based on dichromate oxidation, was used. We compared the results obtained using this method with results of crystal violet destaining and measuring of extracted DNA concentration as proxies of the biofilm biomass. The dichromate oxidation is simple, inexpensive, and fast, and our results show that it may be more sensitive than crystal violet destaining. The highest biomass values tended to associate with high concentrations of the divalent salt. This trend was not observed in treatments where the monovalent salt was added. Our data confirm the importance of inorganic ions for biofilm composition and biomass accumulation.

微生物生物膜在自然界中无处不在，代表了影响人类生活各个方面的重要生物实体。因此，它们在过去几十年中引起了相当大的关注，影响生物膜发展的因素是经常研究的主题之一。在我们的工作中，生物膜是在聚丙烯纤维的表面在由两种未消毒土壤悬浮液接种的营养培养基中培养的。研究了离子强度和盐价对产生的生物膜数量和生物膜微生物群落组成的影响。在一些 OTU 中，效价的影响是显着的：节杆菌属/假节杆菌属/Paenarthrobacter和芽孢杆菌对单价盐 (KCl) 和链霉菌属、赖氨酸杆菌属、假单胞菌属和Ensifer对二价盐 (MgSO ₄ )呈阳性反应。在 OTU农杆菌、芽孢杆菌（均为 100 mM）和短波单胞菌的情况下，观察到对特定浓度盐的显着偏好(30 毫米)。使用了一种基于重铬酸盐氧化测量生物膜生物质中可氧化有机碳的新定量方法。我们将使用这种方法获得的结果与结晶紫脱色和测量提取的 DNA 浓度作为生物膜生物量的代理的结果进行了比较。重铬酸盐氧化简单、廉价且快速，我们的结果表明它可能比结晶紫脱色更敏感。最高的生物量值往往与高浓度的二价盐相关。在添加一价盐的处理中没有观察到这种趋势。我们的数据证实了无机离子对生物膜组成和生物量积累的重要性。