Under laboratory conditions, mating activity in Asian citrus psyllid (ACP) started 4 days after emergence, peaked at day 7, and showed a clear window of activity starting 8 h into the photophase and extending through the first hour of the scotophase. We confirmed that ACP males are attracted to emanations from conspecific females. Traps loaded with a candidate compound enriched with female extract, lignoceryl acetate (24Ac), at various doses were active only after being deployed for several weeks in the field, suggesting that a degradation product, not the test compound, was the active ingredient(s). Lignocerol, a possible product of 24Ac degradation, was not active, whereas acetic acid, another possible degradation product, was found in the airborne volatile collections from lures matured under field conditions and detected in higher amounts in volatiles collected from females at the peak of mating activity than in male samples. Acetic acid elicited dose-dependent electroantennographic responses and attracted ACP males, but not females, in Y-type and 4-way olfactometers. Field tests showed that acetic acid-baited traps captured significantly more males than control traps. Surprisingly, captures of females in acetic acid-baited traps were also higher than in control traps, possibly because of physical stimuli emitted by captured males.
Bifidobacteria are probiotic microorganisms that are widely used in the food industry. With the aim of using of Petrifilm™ Aerobic Count (AC) plates associated with selective culture media, aliquots of sterile skim milk were inoculated separately with four commercial cultures of bifidobacteria. These cultures were plated by both the conventional method and Petrifilm™AC, using the culture media NNLP and ABC. The cultures were incubated under anaerobiosis at 37 °C for 24, 48 and 72 h. No significant differences (p > 0.05) were observed between the obtained counts at 48 and 72 h. Bifidobacteria counts in ABC were usually higher than in NNLP, independent of the plating method. Subsequently, fermented milk was prepared with a Streptococcus thermophilus strain, and aliquots were inoculated with the same bifidobacteria. Then, the fermented milks were submitted to microbiological analysis for bifidobacteria enumeration using the same culture media and methodologies previously described, incubated under anaerobiosis at 37 °C for 48 h. Again, bifidobacteria counts in ABC were higher than in NNLP, with significant differences for some cultures (p < 0.05). The counts obtained by both methodologies presented significant correlations (p < 0.05). The results indicate the viability of Petrifilm™AC as an alternative method for bifidobacteria enumeration when associated to specific culture media, specially the ABC.
Dairy propionibacteria are used as ripening cultures for the production of Swiss-type cheeses, and some strains have potential for use as probiotics. This study investigated the biodiversity of wild dairy Propionibacteria isolates in dairy farms that produce Swiss-type cheeses in Minas Gerais State, Brazil. RAPD and PFGE were used for molecular typing of strains and MLST was applied for phylogenetic analysis of strains of Propionibacterium freudenreichii. The results showed considerable genetic diversity of the wild dairy propionibacteria, since three of the main species were observed to be randomly distributed among the samples collected from different farms in different biotopes (raw milk, sillage, soil and pasture). Isolates from different farms showed distinct genetic profiles, suggesting that each location represented a specific niche. Furthermore, the STs identified for the strains of P. freudenreichii by MLST were not related to any specific origin. The environment of dairy farms and milk production proved to be a reservoir for Propionibacterium strains, which are important for future use as possible starter cultures or probiotics, as well as in the study of prevention of cheese defects.
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