Table 4. Bacterial load (cfu/g) after 1–4 months of storage at -18°C of samples collected at 1st, 4th and 9th time from hives mounting the bottom trap.
| Week of sampling | Microbial parameters | Initial load | Months of storage at -18°C | |||
|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | |||
| 1st | MTVC | 6.91 | 6.48 | 6.48 | 5.78 | 4.48 |
| YM | 5.53 | 2.00 | 3.08 | 2.18 | 2.30 | |
| LAB | 5.48 | 4.54 | 4.43 | 3.28 | 3.08 | |
| Enterobacteriaceae | 5.60 | 5.00 | 4.88 | 4.00 | 4.00 | |
| Bacillus cereus | 2.98 | 4.46 | 3.00 | 2.78 | 2.30 | |
| Staphylococcus aureus | 3.78 | 3.41 | 2.92 | u.d.l.a | u.d.l. | |
| Escherichia coli | u.d.l. | 3.54 | 2.26 | u.d.l. | u.d.l. | |
| Salmonella spp. | -b | - | - | - | - | |
| Clostridium perfringens | - | - | - | - | - | |
| 4th | MTVC | 6.15 | 5.97 | 5.48 | 5.48 | 5.48 |
| YM | 4.11 | 4.88 | 4.54 | 4.30 | 4.80 | |
| LAB | 5.70 | 4.60 | 3.60 | 2.48 | 2.30 | |
| Enterobacteriaceae | 5.30 | 4.25 | 4.54 | 3.30 | 3.30 | |
| Bacillus cereus | 4.49 | 3.18 | u.d.l. | u.d.l. | 4.85 | |
| Staphylococcus aureus | 3.08 | 2.04 | 1.00 | u.d.l. | u.d.l. | |
| Escherichia coli | 3.08 | 2.41 | u.d.l. | u.d.l. | u.d.l. | |
| Salmonella spp. | - | - | - | - | - | |
| Clostridium perfringens | - | - | - | - | - | |
| 9th | MTVC | 5.54 | 5.48 | 4.90 | 4.48 | 4.48 |
| YM | u.d.l. | 3.30 | 3.00 | 3.79 | 3.73 | |
| LAB | 4.50 | 5.08 | 4.00 | 4.18 | 3.95 | |
| Enterobacteriaceae | 4.52 | 3.00 | 3.00 | 4.48 | 4.43 | |
| Bacillus cereus | 3.48 | 3.00 | 3.00 | u.d.l. | u.d.l. | |
| Staphylococcus aureus | 1.00 | 1.00 | u.d.l. | u.d.l. | u.d.l. | |
| Escherichia coli | u.d.l. | 1.00 | u.d.l. | u.d.l. | u.d.l. | |
| Salmonella spp. | +c | - | - | - | - | |
| Clostridium perfringens | + | - | - | - | - | |
Values are means of three independent replicates and standard deviation was always less then 1% of mean value.
au.d.l.: under detectable limit of 10 cfu/g.
b-: absent in 25 g of pollen.
c+: present in 25 g of pollen.