Bacteria of the families Lactobacilaceae and Streptococcaceae were isolated from cocoa beans fermented by the traditional method used in the State of Bahia (Brazil). During the first 48 hr of the process these bacteria were better established than the yeasts. This observation differs from those reported by other researchers working in other countries. Identification studies showed eight homolactic species: Lactobacillus plantarum, Lactobacillus casei, Lactobacillus delbrueckii, Lactobacillus acidophilus, Lactobacillus lactis, Pediococcus cerevisiae, Pediococcus acidilactici, Streptococcus lactis and two heterolactic species: Leuconostoc mesenteroides and Lactobacillus brevis. L. plantarum was found better distributed and the thermophile L. delbrueckii was found to constitute 26% of the population at 16 hr.
Pectin lyase (PL) induction by organic and inorganic components of yeast extract (YE) was evaluated in Penicillium griseoroseum, cultured in a mineral medium containing sucrose, by determining PL activity (A235) and mycelial growth (mycelial dry weight). The lowest YE concentration that promoted significant PL induction without acting as a carbon source for the fungus corresponded to 0.0075%. Neither calcined YE nor a nutrient solution containing micronutrients induced PL production, indicating that the inducer was an organic compound. Vitamins, phospholipid components, amino acids, and nitrogenous bases were tested in place of YE and promoted no significant PL induction. A PL inducer compound was found to be soluble in the nucleotide fraction obtained during extraction of YE. The inducer was shown to be a thermostable polar substance dialyzable at 2000 Daltons, hydrolyzable by HCl, and activated by boiling for up to 60 min. Cyclic AMP (cAMP) exogenously added to the culture medium at 5 and 10 mM was capable of inducing PL in P. griseoroseum grown on sucrose, suggesting that at least one compound may be present in YE acting in a cooperative fashion for the maintenance of high levels of cAMP into the cell. PL activity and the level of cAMP inside the fungal cells increased after the addition of YE to the culture medium, suggesting the participation of this messenger in this enzyme's synthesis.
The ability to differentiate functional and structural diversity of bacterial communities present in activated sludges adapted to elementally (ECF) and totally (TCF) chlorine-free bleaching effluents was evaluated. Community function was evaluated through substrate utilization patterns in BiologGN microplates, and taxonomic structure was evaluated by fluorescent in situ hybridization using probes targeting the Eubacteria; the alpha, beta, and gamma subclasses of the Proteobacteria; and gram-positive bacteria with high GC content. Over 6-week sampling periods, ECF-and TCF-adapted sludge bacterial communities presented reproducible substrate utilization patterns that through principal components (PCs) analysis, separated the ECF samples from the TCF samples. Application of the fluorescent in situ hybridization technique was complicated by the intense autofluorescence of the bleaching effluent sludge samples that interfered with detection of specific hybridization signals. The most notable difference in community structure detected using the chosen set of probes was the relatively greater proportion of cells of the alpha subclass in TCF sludge (27%) than in ECF sludge (6%). Nonspecific hybridization with beta and gamma probes was relatively high, but both sludges appeared to have similar proportions of cells of the beta (20-22%) and gamma (11-12%) subclasses. The two sludges presented relatively few gram-positive cells with high GC content (<0.2% of eubacterial counts). Differences in both metabolic potential and taxonomic structure of the microbial communities in the ECF- and TCF-activated sludges were detected. The kinetics of the development of these differences in treatment plants and their relationships with treatment efficiency and production process conditions should now be evaluated.
Aerobic spore forming bacteria isolated from traditional cacao fermentations in Bahia were identified in the genus Bacillus: B. subtilis, B. licheniformis, B. firmus, B. coagulans, B. pumilus, B. macerans, B. polymyxa, B. laterosporus, B. stearothermophilus, B. circulans, B. pasteurii, B. megaterium, B. brevis, and B. cereus. In the first 8 hr of the fermentations, similar percentages of ten species were found in the distribution. During the fermentation process the amount of spore‐forming bacteria increased and B. subtilis, B. circulans, and B. licheniformis appeared more frequently.
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