Oxford University Press (OUP)

The value of iron ore is adversely affected by phosphorus in concentrations over 0.03% by weight. The present research concerns the use of metabolic products of aPenicillium-like fungus to leach insoluble phosphates (hydroxyapatite) from ores. Ion chromatography was used to measure metabolism of glucose into acidic fragments. The rate and products of glucose degradation depended on both the chemical composition of the growth medium (buffered or not) and incubation conditions (shaken or quiescent). The principal products were identified as oxalic acid and isomers of propylene dicarboxylic acid, mainly itaconic acid. Continued, slow metabolism of itaconic acid generates more oxalic acid. Aliphatic acids were not detected. Both iron ore phosphate and calcium phosphate were partially solubilized by either the spent broth or aqueous oxalic acid. Solubilization of ore phosphorus was greatly assisted by hydrochloric acid added to the spent broth in small increments. The data suggest biological alternatives to costly leaching procedures that use only mineral acids.

A variety of bactericidal tests are available for evaluating the antimicrobial activity of products. An often overlooked variable in these types of studies is adequate neutralization. Triclosan is a widely used antimicrobial agent and has been shown to be difficult to neutralize. Incomplete neutralization may overestimate the efficacy of triclosan-containing products.

Mevalocidin is a fungal secondary metabolite produced by Coniolariella sp. It is a unique phytotoxin that demonstrates broad spectrum post-emergent herbicidal properties. With limited options for weed control, the commercialization of a natural product pesticide would be beneficial to organic farming. In this study, two mevalocidin-producing fungal strains, coded MSX56446 and MSX92917, were explored under a variety of growth conditions, including time, temperature, and media. The concentration of mevalocidin was quantitatively measured via LC–MS to determine the optimal setting for each condition. Maximum production was achieved for each condition at 20 days, at 30 °C, with YESD + agar, and with a media containing 2.5 % dextrose. Furthermore, an advanced surface sampling technique was incorporated to gain a better understanding of the fungal culture’s natural ability to biosynthesize and distribute this herbicide into its environment. It was shown that both fungi actively exude mevalocidin into their environment via liquid droplet formations known as guttates.

Succinate production was studied in Escherichia coli AFP111, which contains mutations in pyruvate formate lyase (pfl), lactate dehydrogenase (ldhA) and the phosphotransferase system glucosephosphotransferase enzyme II (ptsG). Two-phase fermentations using a defined medium at several controlled levels of pH were conducted in which an aerobic cell growth phase was followed by an anaerobic succinate production phase using 100% (v/v) CO2. A pH of 6.4 yielded the highest specific succinate productivity. A metabolic flux analysis at a pH of 6.4 using 13C-labeled glucose showed that 61% of the PEP partitioned to oxaloacetate and 39% partitioned to pyruvate, while 93% of the succinate was formed via the reductive arm of the TCA cycle. The flux distribution at a pH of 6.8 was also analyzed and was not significantly different compared to that at a pH of 6.4. Ca(OH)2 was superior to NaOH or KOH as the base for controlling the pH. By maintaining the pH at 6.4 using 25% (w/v) Ca(OH)2, the process achieved an average succinate productivity of 1.42 g/l h with a yield of 0.61 g/g.

The toxicities of three organotin compounds were examined on natural populations of microorganisms in sediments from Boston Harbor. Mono-, di-and trimethyltins were toxic to organisms from these sediments, and the di-and trimethyl compounds were more toxic than the monomethyl compound as measured by either viable counts or by [3H]thymidine uptake. Approximately three to eight times as much organotin was required to achieve the same effect measured by thymidine uptake as measured by viable counts. The results of replica plating experiments suggest that most estuarine organisms which are resistant to one methyltin will be resistant to other methyltins. LC-values suggest that at concentrations reported for methyltins in aquatic environments, methyltins alone are not likely to cause major alterations in the microbial flora. However, these compounds may combine with other stressors to alter the composition of natural populations.