In this research, we isolated and characterized Streptomyces strains, endemic from sugar beet fields of the Beni-Mellal region, able to use natural rock phosphate (RP) and tricalcium phosphate (TCP), as sole phosphate source. Ten Streptomyces isolates yielded a comparable biomass in the presence of these two insoluble phosphate sources, indicating that they were able to extract similar amount of phosphorus (P) from the latter for their own growth. Interestingly, five strains released soluble P in large excess from TCP in their culture broth whereas only two strains, BP, related to Streptomyces bellus and BYC, related to Streptomyces enissocaesilis, released a higher or similar amount of soluble P from RP than from TCP, respectively. This indicated that the rate of P released from these insoluble phosphate sources exceeded its consumption rate for bacterial growth and that most strains solubilized TCP more efficiently than RP. Preliminary results suggested that the solubilization process of BYC, the most efficient RP and TCP solubilizing strain, involves both acidification of the medium and excretion of siderophores. Actinomycete strains possessing such interesting RP solubilizing abilities may constitute a novel kind of intrans beneficial for plant nutrition and more environmentally friendly than chemical fertilizers in current use.

Insoluble contaminant or a varnish is a result of oil degradation by products and sometimes depleted additive molecules. This process is in most cases initiated by thermal stress placed on the oil. In tribology varnish becomes a significant problem for modern complex machinery lubrication systems as it has severe debilitating effects such as loss of operating clearances and heat transfer. Problems arising from varnish build-up in lubricants can be inhibited by timely oil analysis which gives us important information about oil-degradation level and current insoluble contaminants potential of oil. There are several laboratory testing methods to describe varnish potential. The most applied one is a colorimetric analysis, also known as MPC (Membrane Patch Colorimetry) as it tends to be reasonably quick and cost-effective. This study applies principles generally used for MPC test of turbine oils to measure lubricant generated insoluble contaminants of hydraulic fluids. For this purpose, in-service oil samples were taken from hydraulic circuits of rubber vulcanizing presses and analyzed using testing method based on method defined by standard ASTM D7843 – 21. Accuracy of this testing method is dependent on development time of tested sample. Therefore, we not only try to proof applicability of this method for hydraulic oils but also want to determine incubation time needed for efficient and accurate determination of concentration of insoluble contaminants in the sample.

The total, soluble and insoluble oxalate contents of fresh and wok-fried fat hen (Chenopodium album) leaves were extracted and measured using HPLC chromatography. The total oxalate content of the raw leaves was 1112.4 mg/100 g dry matter (DM), and the levels were significantly reduced by boiling (682.8 mg/100 g DM) or cooking the leaves in a wok (883.6 mg/100 g DM). The percentages of soluble oxalate contents in the total oxalates of the raw and boiled leaves were similar (mean 75%), while the proportion of soluble oxalate content in the wok-fried leaves were reduced to 53.4% of the total, giving a significant increase in the insoluble oxalate content of the wok-fried leaves. The percentage of insoluble calcium in the total calcium was significantly reduced (P < 0.05) when the leaves were boiled but the insoluble oxalate content significantly increased (67.2%) in the wok-fried leaves when compared to the content of the original raw leaves. Processing the cooked leaves into pesto or extracting the juice gave final products that contained significantly reduced total and soluble oxalate contents. The addition of calcium chloride to the juice made a very small reduction in the soluble oxalate content in the juice.