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© 2005 by CRC Press
16
Role of Fluorescent
Pseudomonads and
Their Pectolytic Enzymes
in Spoilage of Fresh and
Fresh-Cut Produce
Ching-Hsing Liao and Dike Ukuku
Eastern Regional Research Center, U.S. Department of
Agriculture1, Agricultural Research Service, Wyndmoor, PACONTENTS
16.1 Introduction................................................................................................ 484
16.2 PF Pseudomonads as a Major Cause of Produce Spoilage ...................... 485
16.2.1 Physiological Diversity of PF Pseudomonads ........................... 485
16.2.2 Occurrence of PF Pseudomonads on Fresh Produce ................. 486
16.3 Biochemical Characterization of Pectate Lyase........................................ 487
16.3.1 Production of Pectic Enzymes and Other Depolymerases
by PF Pseudomonads.................................................................. 487
16.3.2 Description of the Erwinia Pectic Enzyme System................... 488
16.3.3 Description of the Pseudomonas Pectic Enzyme System ......... 489
16.3.4 Purification, Enzymatic Properties, and Tissue-Macerating
Ability of Pseudomonas PLs...................................................... 489
16.4 Molecular Genetic Analysis of PL Production by PF Pseudomonads ..... 490
16.4.1 Analysis of Transposon (TN5) Mutants Deficient
in PL Production and Secretion ................................................. 490
16.4.2 Cloning and Characterization of the pel Genes
from Non-Erwinia Pectolytic Bacteria....................................... 490
16.4.3 Mechanisms Regulating the Production and Secretion of PL ... 491
16.5 Interactions of PF Pseudomonads and Native Microflora
on Fresh Produce ....................................................................................... 492
1 Mention of trade names or commercial products in this chapter is solely for the purpose of providing
specific information and does not imply recommendation or endorsement by the U.S. Department of
Agriculture.