Article Figures & Data
Figures
- FIG. 1.
Riboprints of Pseudomonas isolates obtained from dairy processing plant D.
- FIG. 2.
Relationship between ribotypes and enzyme activities of Pseudomonas spp. Mean activities and standard deviations are reported as follows: mean ratio reflecting protease activity = clearance zone diameter/colony size; mean ratio reflecting lecithinase activity = opaque zone diameter/colony size; lipase activity = mean color intensity; n = the number of isolates within a ribotype.
Tables
- TABLE 1.
Number of Pseudomonas isolates and ribotypes obtained from each dairy processing plant
Sample source Dairy A Dairy B Dairy C Dairy D Total No. of isolates No. of ribotypesa No. of isolates No. of ribotypes No. of isolates No. of ribotypes No. of isolates No. of ribotypes No. of isolates No. of ribotypes Processed milk 28 1 (3) 60 6 (9) 57 5 (12) 56 8 (12) 201 21 (36) Raw milk 12 3 (6) 10 4 (5) 10 3 (3) 15 5 (6) 47 15 (20) Environment 4 3 (3) 30 5 (5) 23 5 (5) 33 6 (12) 90 17 (25) Total 54 7 (12) 100 14 (19) 90 13 (20) 104 17 (30) 338 42 (81) ↵ a Numbers in parentheses indicate the number of isolates selected for ribotyping.
- TABLE 2.
Sources, ribotypes, and enzyme activities of Pseudomonas isolates
Dairy and visit Strain API 20 NE identificationa Ribotype Sample source (day of plating) Enzyme activityb Protease Lecithinase Lipase Dairy A Secondc D3-105 P. fluorescens 407-S-3 Processed milk (7) 2.8 ± 0.3 1.6 ± 0.1 3 D3-111 P. fluorescens 407-S-3 Processed milk (7) 2.6 ± 0.1 1.6 ± 0.0 3 D3-121 P. fluorescens 407-S-3 Processed milk (14) 2.8 ± 0.1 1.5 ± 0.1 3 D3-221 P. fluorescens 48-S-6 Raw milk 2.9 ± 0.1 1.4 ± 0.1 1 D3-222 P. fluorescens 48-S-6 Raw milk 2.7 ± 0.0 1.3 ± 0.1 1 D3-223 P. putida d 82-S-6 Raw milk 3.6 ± 0.5 — 3 D3-224 P. fluorescens 82-S-6 Raw milk 3.6 ± 0.2 — 3 D3-227 P. fluorescens 55-S-6 Raw milk 3.7 ± 0.1 — 3 D3-229 P. putida d 82-S-6 Raw milk 3.7 ± 0.4 — 3 Third D3-381 P. fluorescens 542-S-7 Floor 2.1 ± 0.2 2.1 ± 0.2 1 D3-382 P. fluorescens 424-S-8 Floor 2.8 ± 0.3 2.2 ± 0.1 1 D3-384 P. fluorescens e 542-S-8 Floor — — — Dairy B First D3-046 P. fluorescens e 51-S-5 Processed milk (7) — — — D3-047 P. fluorescens e 51-S-5 Processed milk (7) — — — D3-050 P. fluorescens e 51-S-5 Processed milk (7) — — — D3-061 P. putida 384-S-2 Processed milk (14) — — — Second D3-313 P. fluorescens 524-S-5 Processed milk (1) 3.0 ± 0.1 — 3 D3-314 P. putida d 57-S-5 Processed milk (7) — — 1 D3-321 P. putida d 57-S-5 Processed milk (7) — — 2 D3-326 P. aeroginosa d 524-S-7 Processed milk (7) 1.7 ± 0.3 2.0 ± 0.2 1 D3-309 P. putida d 82-S-6 Processed milk (14) 1.6 ± 0.1 — 2 D3-153 P. fluorescens f 408-S-1 Raw milk 2.4 ± 0.3 1.6 ± 0.2 — D3-156 P. fluorescens 424-S-8 Raw milk 1.4 ± 0.4 2.2 ± 0.1 1 D3-157 P. fluorescens 408-S-3 Raw milk — 2.2 ± 0.2 — D3-158 P. putida 82-S-4 Raw milk — — — D3-161 P. fluorescens k 408-S-3 Raw milk — 2.3 ± 0.3 1 Third D3-352 P. fluorescens 50-S-8 Floor 2.5 ± 0.4 2.4 ± 0.2 4 D3-367 P. putida 537-S-7 Floor — — — D3-363 P. putida 537-S-5 Inside filling bowl 2.5 ± 0.1 1.6 ± 0.1 2 D3-364 P. fluorescens e 537-S-6 Inside filling bowl — — — D3-375 P. putida 82-S-4 Drain — — — Dairy C First D3-016 P. fluorescens 48-S-7 Processed milk (7) 2.7 ± 0.1 1.8 ± 0.1 1 D3-017 P. fluorescens e 375-S-5 Processed milk (7) — — 4 D3-018 P. fluorescens e 375-S-5 Processed milk (7) — — 4 D3-021 P. fluorescens 48-S-7 Processed milk (7) 2.6 ± 0.2 1.8 ± 0.2 1 D3-029 P. putida 72-S-3 Processed milk (7) — — 4 D3-032 P. putida 377-S-5 Processed milk (14) — — — D3-034 P. putida 377-S-5 Processed milk (14) — — — Second D3-147 P. fluorescens e 72-S-3 Processed milk (1) — — 4 D3-133 P. fluorescens e 72-S-3 Processed milk (7) — — 4 D3-168 P. fluorescens 72-S-3 Processed milk (14) — — 4 D3-170 P. fluorescens e 72-S-3 Processed milk (14) — — 4 D3-175 P. fluorescens 408-S-8 Processed milk (14) 3.2 ± 0.3 2.3 ± 0.3 4 D3-148 P. fluorescens 112-S-6 Raw milk 3.0 ± 0.2 1.3 ± 0.0 3 D3-149 P. fluorescens 409-S-3 Raw milk 3.2 ± 0.3 1.5 ± 0.3 3 D3-167 P. putida 384-S-2 Raw milk — — — Third D3-328 P. fluorescens 536-S-6 Floor — — — D3-331 P. fluorescens 57-S-8 Floor 2.8 ± 0.1 1.8 ± 0.2 2 D3-338 P. putida 536-S-7 Drain — — — D3-348 P. fluorescens 536-S-8 Overhead pipe filler — 1.53 ± 0.0 — D3-350 P. fluorescens 112-S-2 Overhead pipe filler 3.3 ± 0.1 1.5 ± 0.1 1 Dairy D First D3-077 P. fluorescens 384-S-3 Processed milk (7) 2.5 ± 0.2 2.6 ± 0.2 2 D3-086 P. fluorescens 97-S-4 Processed milk (7) 2.7 ± 0.4 1.9 ± 0.1 4 D3-092 P. fluorescens 543-S-6 Processed milk (14) 1.9 ± 0.0 2.5 ± 0.2 1 D3-094 P. fluorescens 97-S-4 Processed milk (14) 1.3 ± 0.0 2.0 ± 0.3 2/PICK> Second D3-182 P. fluorescens g 112-S-2 Processed milk (7) 2.8 ± 0.1 1.4 ± 0.1 1 D3-183 P. fluorescens e 409-S-6 Processed milk (7) — — — D3-184 — 409-S-6 Processed milk (7) — — — D3-187 P. putida h 409-S-8 Processed milk (7) — — — D3-193 P. fluorescens 416-S-8 Processed milk (7) 3.4 ± 0.4 1.8 ± 0.2 1 D3-195 P. fluorescens 422-S-2 Processed milk (14) 2.5 ± 0.4 — — D3-196 P. fluorescens 422-S-2 Processed milk (14) 2.6 ± 0.2 — — D3-197 P. fluorescens 422-S-2 Processed milk (14) 2.7 ± 0.3 — — D3-180 P. fluorescens 57-S-8 Raw milk 3.0 ± 0.2 1.7 ± 0.0 2 D3-181 P. fluorescens 409-S-5 Raw milk 3.0 ± 0.3 1.4 ± 0.0 1 D3-210 P. putida d 57-S-5 Raw milk — — 1 D3-211 P. fluorescens e 48-S-6 Raw milk — 1.8 ± 0.5 — D3-212 P. fluorescens 48-S-6 Raw milk 2.4 ± 0.1 1.6 ± 0.2 4 D3-213 P. fluorescens e 72-S-3 Raw milk — — 4 Third D3-266 P. fluorescens 524-S-1 Floor 2.6 ± 0.1 3.0 ± 0.3 1 D3-267 P. fluorescens 112-S-2 Floor 2.9 ± 0.3 1.4 ± 0.0 1 D3-269 P. fluorescens 112-S-2 Floor 3.0 ± 0.2 1.4 ± 0.2 1 D3-270 P. fluorescens i 112-S-2 Floor 2.6 ± 0.1 1.4 ± 0.0 1 D3-274 P. fluorescens j 537-S-2 Floor — — — D3-276 P. fluorescens g 112-S-2 Valve 3.0 ± 0.1 1.3 ± 0.1 1 D3-283 P. fluorescens 112-S-2 Valve 3.3 ± 0.3 1.4 ± 0.1 1 D3-286 P. fluorescens 112-S-2 Drain 2.7 ± 0.2 1.3 ± 0.2 1 D3-287 P. fluorescens 57-S-8 Drain 3.0 ± 0.1 1.8 ± 0.0 2 D3-293 P. fluorescens j 82-S-6 Drain 2.7 ± 0.1 — 3 D3-294 P. fluorescens 536-S-4 Drain 3.3 ± 0.5 2.30 ± 0.2 1 D3-296 P. putida 82-S-6 Pipe lines 2.0 ± 0.3 — 2 ↵ a Species were assigned by best likelihood.
↵ b Enzyme activities ± standard deviations are reported as follows: mean ratio reflecting protease activity = clearance zone diameter/colony size; mean ratio reflecting lecithinase activity = opaque-zone diameter/colony size; lipase activity = mean color intensity; —, not detectable.
↵ c Pseudomonas spp. could not be isolated on the first visit.
↵ d Another possibility is P. fluorescens.
↵ e Another possibility is P. putida.
↵ f Another possibility is Burkholderia cepacia.
↵ g Other possibilities are Burkholderia pseudomallei, P. aeruginosa, and Chromobacterium violaceum.
↵ h Other possibilities are P. fluorescens and Ralstonia pichettii.
↵ i Other possibilities are P. stutzeri and P. putida.
↵ j Another possibility is P. aeruginosa.
↵ k Other possibilities are B. cepacia and Ochrobactrum anthropi.
- TABLE 3.
Ribotypes and enzyme activity profiles of Pseudomonas isolates
Ribotype No. of isolates Enzyme activity profile Source(s)a and/or reference Protease Lecithinase Lipase 48-S-6 10 + + + A2, D2; 32 2 − + − D2; 32 48-S-7 12 + + + C1; 32 1 + + − 32 50-S-8 3 + + + B3; 32 51-S-5 5 − − − B1; 32 55-S-6 2 + − + A2; 32 57-S-5 4 − − + B1, D2; 32 57-S-8 3 + + + C3, D2, D3 1 − − − 32 72-S-3 8 − − + C1, D2, 32 1 − − − 32 82-S-4 3 − − − B2, B3; 32 82-S-6 7 + − + A2, B1, D3; 32 1 + − − 32 97-S-4 3 + + + D1; 32 111-S-5 2 + + + 32 112-S-2 8 + + + C3, D1, D3 375-S-5 2 − − + C1 377-S-5 2 − − − C1 384-S-2 2 − − − B1, C2 407-S-3 3 + + + A1 408-S-3 2 − + + B2 409-S-6 2 − − − D1 422-S-2 3 + − − D1 424-S-8 2 + + + A3, B2 ↵ a Letters indicate dairy plants A, B, C, and D, and numbers indicate samples from processed milk (1), raw milk (2), or the plant environment (3).
- TABLE 4.
SPC, mean flavor scores, and percentage of enzymatically active Pseudomonas isolates from processed milk samples
Visit Sample source and day of plating SPC/ml No. of Pseudomonas isolates tested % of Pseudomonas isolates with enzyme activity Flavor score Sensory result(s) Protease Lecithinase Lipase First Dairy B Day 7 7.1 × 106 15 0 0 0 7.8 Lacks freshness, light oxidized Day 14 1.3 × 108 16 0 0 0 1 Coagulated Dairy C Day 7 1.2 × 107 15 13 80 100 6.4 Lacks freshness, rancid Day 14 2.6 × 108 15 0 80 80 1 Rancid Dairy D Day 7 1.5 × 104 14 100 100 100 8.4 Lacks freshness Day 14 1.9 × 108 14 100 100 100 7.7 Lacks freshness Second Dairy A Day 7 2 × 103 15 100 100 100 8.7 No criticism Day 14 5.3 × 104 13 100 100 100 7.6 Lacks freshness Dairy B Day 7 6 × 107 14 36 78 100 1.3 Rancid Day 14 4.7 × 108 14 64 21 71 NTa NT Dairy C Day 7 2.7 × 107 14 0 0 100 5.1 Fruity or fermented, lacks freshness Day 14 1.4 × 108 12 67 58 100 2.5 Rancid Dairy D Day 7 2.4 × 105 13 38 38 38 8.2 Cooked, lacks freshness Day 14 3.2 × 108 15 100 0 0 NT NT ↵ a NT, not tasted due to presence of coliforms.
