Foam mitigation and exploitation in biosurfactant production.

Biosurfactants could potentially outperform traditional surfactants in many applications whilst being more sustainable to source, manufacture, use and dispose of. However, currently available fermentation production methods are too inefficient to manufacture biosurfactants for these high volume markets. Foaming in an inherent issue with biosurfactant production and adds significantly to the cost of production using traditional unit operations. This review illustrates how the application of process engineering has enabled nuisance foaming to be transformed into a cost saving feature of the production system. The scope of biosurfactants and their application is discussed and the fundamentals of foam generation and control are reviewed. The range of specific phenomena associated with the interaction of foams with bioproducts is assessed. Finally, recent work which has aimed at taking advantage of some of these phenomena in order to intensify the biosurfactant production process is discussed in detail.

Pesticide removal from waste spray-tank water by organoclay adsorption after field application: an approach for a formulation of cyprodinil containing antifoaming/defoaming agents.

PURPOSE: Many reports on purification of water containing pesticides are based on studies using unformulated active ingredients. However, most commercial formulations contain additives/adjuvants or are manufactured using microencapsulation which may influence the purification process. Therefore, the main objective of this work was to develop and test a pilot scheme for decontaminating water containing pesticides formulated with antifoaming/defoaming agents. METHODS: The Freundlich adsorption coefficients of formulation of cyprodinil, a new-generation fungicide, onto the organoclay Cloisite 20A have been determined in the laboratory in order to predict the efficiency of this organoclay in removing the fungicide from waste spray-tank water. Subsequently, the adsorption tests were repeated in the pilot system in order to test the practical operation of the purification scheme. RESULTS: The laboratory adsorption tests successfully predicted the efficiency of the pilot purification system, which removed more than 96% cyprodinil over a few hours. The passing of the organoclay-cyprodinil suspension through a layer of biomass gave 100% recovery of the organoclay at the surface of the biomass after 1 week. The organoclay was composted after the treatment to try to break down the fungicide so as to allow safe disposal of the waste, but cyprodinil was not significantly dissipated after 90 days. CONCLUSION: The purification scheme proved to be efficient for decontaminating water containing cyprodinil formulated with antifoaming/defoaming agents, but additional treatments for the adsorbed residues still appear to be necessary even for a moderately persistent pesticide such as cyprodinil. Furthermore, a significant conclusion of this study concerns the high influence of pesticide formulations on the process of purification of water containing these compounds, which should be taken into account when developing innovative decontamination schemes, especially for practical applications.

Characterisation of HFBII biosurfactant production and foam fractionation with and without antifoaming agents.

The effects of foaming on the production of the hydrophobin protein HFBII by fermentation have been investigated at two different scales. The foaming behaviour was characterised in standard terms of the product enrichment and recovery achieved. Additional specific attention was given to the rate at which foam, product and biomass overflowed from the fermentation system in order to assess the utility of foam fractionation for HFBII recovery. HFBII was expressed as an extracellular product during fed-batch fermentations with a genetically modified strain of Saccharomyces cerevisiae, which were carried out with and without the antifoam Struktol J647. In the presence of antifoam, HFBII production is shown to be largely unaffected by process scale, with similar yields of HFBII on dry matter obtained. More variation in HFBII yield was observed between fermentations without antifoam. In fermentations without antifoam, a maximum HFBII enrichment in the foam phase of 94.7 was measured with an overall enrichment, averaged over all overflowed material throughout the whole fermentation, of 54.6 at a recovery of 98.1%, leaving a residual HFBII concentration of 5.3 mg L(-1) in the fermenter. It is also shown that uncontrolled foaming resulted in reduced concentration of biomass in the fermenter vessel, affecting total production. This study illustrates the potential of foam fractionation for efficient recovery of HFBII through simultaneous high enrichment and recovery which are greater than those reported for similar systems.

alpha-Galactosidase from Bacillus megaterium VHM1 and its application in removal of flatulence-causing factors from soymilk.

A bacterial strain capable of producing extracellular alpha-galactosidase was isolated from sugar cane industrial waste soil sample. Microbiological, physiological, and biochemical studies revealed that isolate belonged to Bacillus sp,. Furthermore, 16S rDNA sequence analysis of new isolates was identified as Bacillus megaterium VHM1. The production of alpha-galactosidase was optimized by various physical culture conditions. Guar gum and yeast extract acted as the best carbon and nitrogen source, respectively for the production of alpha-galactosidase. The enzyme showed an optimum pH at 7.5 and was stable over a pH between 5 and 9. The enzyme was optimally active in 55degreesC and the enzyme was thermostable with half life of 120 minutes at 55 degrees C and lost their 90%, residual activity in 120 minutes at 60 degrees C. alpha-Galactosidase was strongly inhibited by Ag2, Cu2, and Hg2+ at 1mM concentration. The metal ions Fe2, Mn2+, and Mg2+ had no effect on alpha-galactosidase activity, Zn2+,Ni2+, and Ca2+ reduced the enzyme activity slightly. The B megaterium VHM1 enzyme treatment completely hydrolyzed flatulence-causing sugars of soymilk within one and half hour.