Effect of reduced water activity on vegetative growth of cells and on germination of endospores of Sporolactobacillus.
Growth of vegetative cells and germination of endospores of Sporolactobacillus at reduced water activity (aw) values were studied with NaCl and glycerol as humectants, and compared with Bacillus cereus and Clostridium sporogenes. With NaCl the highest aw for complete inhibition of both growth of vegetative cells and germinated spores of Sporolactobacillus was 0.955. With glycerol, growth of vegetative cells was completely inhibited at 0.905 as compared to 0.880 for vegetative growth resulting from germinated endospores. The mechanism of this phenomenon cannot be explained yet. NaCl appeared to have a toxic effect, in addition to inhibition by reduced aw per se.
Self-preserving gelatin emulgel containing whole cell probiotic for topical use: preclinical safety, efficacy, and germination studies
ABSTRACT Background Dermal disorders, owing to disruption of skin-microflora balance can be served by direct application of probiotics. However, there are few topical whole probiotic products in market because of (i) loss of viability during manufacturing and storage(ii) inadequate germination and retention on skin. Presently we report a novel (IPA 201811010395) emulgel incorporatingBacillus coagulans (Unique IS-2) for possible topical use. Methods Developed emulgel was characterized for particle size, texture, rheology, morphology, water activity, self-preservation, safety, and stability. Results We successfully incorporated 97 ± 5% (1.7×108CFU/g) Bacillus coagulans in honeycomb network of gelatin nanoparticles (≈600 nm). Maintenance of CFU at 30 ± 2°C, 65 ± 5% RH for 3 months confirmed viability of incorporated probiotic. Low water-activity (0.66–0.732aw) and challenge test (0.05–0.5% viability) confirmed its self-preserving nature. Early initiation (6 h) and complete (24 h) spore germination was evident onrabbit skin. No cytotoxicity, dermal irritation or translocation established its safety. Faster wound closure and reduced oxidative stress (LPO, catalase, SOD, glutathione reductase) in comparison to Soframycin® (1%w/w Framycetin) was observed in excision wound in mice. Conclusions A whole cell probiotic formulation that is self-preserving, maintains probiotic viability, guarantees germination, and has wound healing properties was successfully formulated.
Inhibition of Root Growth and Polyamine Metabolism in Sunflower (Helianthus annuus) Seedlings Under Cadmium and Copper Stress
Although sunflower is usually regarded as a highly tolerant crop, impairment of root growth at initial stages of plant development may result in poor crop establishment and higher susceptibility to pathogen attack. In order to evaluate if Cd2+ and Cu2+ may impact on sunflower germination and initial root development, a pot experiment under controlled conditions was carried out. Possible involvement of polyamine metabolism in sunflower response to these stressors was also investigated. Although Cd2+ and Cu2+ treatments affect neither seed germination nor radicle emergence, sunflower seedlings grown in the presence of these heavy metals showed significant inhibition of root growth, being this inhibition greater for Cd2+. Both metals caused significant increases in proline contents at the highest concentrations tested (0.5 and 1 mM), and these increments were more pronounced for Cd2+ treatments, especially between days 3 and 10. Metals also increased putrescine (Put) contents at all concentrations assayed from the seventh day onward, causing no variations on this polyamine time-course pattern. Spermine and spermidine contents, however, were increased only by 1 mM Cd2+. Arginine decarboxylase seems to have been the enzyme responsible for Put increases under both metal treatments. This work demonstrates that initial root growth of sunflower seedlings may be significantly impaired in Cd2+ or Cu2+ contaminated soils. It also shows that polyamines are key biological compounds, which are probably involved in signaling pathways triggered under stress environmental conditions.