Recovery of a Bacteriocin-Like Inhibitory Substance from Lactobacillus bulgaricus FTDC 1211 Using Polyethylene-Glycol Impregnated Amberlite XAD-4 Resins System.

Lactobacillus bulgaricus is a LAB strain which is capable of producing bacteriocin substances to inhibit Staphylococcus aureus. The aim of this study was to purify a bacteriocin-like inhibitory substance (BLIS) produced by L. bulgaricus FTDC 1211 using an aqueous impregnated resins system consisting of polyethylene-glycol (PEG) impregnated on Amberlite XAD4. Important parameters influencing on purification of BLIS, such as the molecular weight and concentration of PEG, the concentration and pH of sodium citrate and the concentration of sodium chloride, were optimized using a response surface methodology. Under optimum conditions of 11% (w/w) of PEG 4000 impregnated Amberlite XAD4 resins and 2% (w/w) of sodium citrate at pH 6, the maximum purification factor (3.26) and recovery yield (82.69% ± 0.06) were obtained. These results demonstrate that AIRS could be used as an alternate purification system in the primary recovery step.

Ectoine production with indigenous Marinococcus sp. MAR2 isolated from the marine environment.

Ectoine has fostered the development of products for skin care and cosmetics. In this study, we employed the marine bacterial strain Marinococcus sp. MAR2 to increase ectoine production by optimizing medium constituents using Response Surface Methodology (RSM) and a fed-batch strategy. The results from the steepest ascent and central composite design indicated that 54 g/L of yeast extract, 14.0 g/L of ammonium acetate, 74.4 g/L of sodium glutamate, and 6.2 g/L of sodium citrate constituted the optimal medium with maximum ectoine production (3.5 g/L). In addition, we performed fed-batch culture in the bioreactor, combining pH and dissolved oxygen to produce ectoine by Marinococcus sp. MAR2. The ectoine production, content, and productivity of 5.6 g/L, 10%, and 3.9 g/L/day were further reached by a fed-batch culture. Thus, the ectoine production by Marinococcus sp. MAR2 using RSM and fed-batch strategy shows its potential for industrial production.

X-ray diffraction has limited applicability in investigation of milk tampering.

The aim of this work was to use X-ray diffraction to identify substances used for adulteration of raw milk and to determine if crystallographic analysis can detect extraneous substances in milk. Two unknown substances were sent anonymously by employers linked to the dairy chain, who claimed that they were added directly in milk prior to water addition by truck drivers. The samples were analyzed by X-ray diffraction and submitted to physicochemical analysis. The first substance was identified by X-ray diffraction as sodium citrate, complying with its physicochemical attributes, such as the powerful ability to decrease the freezing point. The second substance was identified by X-ray diffraction as sucrose and this result was also in agreement with its ability to increase the density, decrease the freezing point and finally, to be positive for sucrose in the resorcinol qualitative test. To evaluate if X-ray diffraction can detect extraneous substances already mixed in milk, fresh raw milk samples tampered with urea, sodium hydroxide, sodium citrate and sucrose were freeze dried and analyzed by X-ray diffraction, with no detection of any extraneous substances at any percentage. This is the first report of attempted diagnosis of extraneous substances in milk by X-ray diffraction. However, this technique can be useful only when applied to identify substances used for adulteration prior to its dilution in milk, since the amorphous nature of milk seems to be a limitation for the accurate detection of extraneous substances.