Document Type

Honors Project

First Advisor

Stephen F. Baron

Degree Award Date

Spring 2022


Streptomyces sp. SFB5A., phaZ, PCR, biodegradable plastics, bld4 mutant, PHB depolymerase


Environmental Microbiology and Microbial Ecology


There is considerable interest in using biodegradable plastics to reduce plastic waste. Polyhydroxybutyrate (PHB) is a natural, biodegradable plastic that can be broken down by PHB depolymerases secreted by environmental bacteria. The wild type strain of Streptomyces sp. SFB5A forms powdery colonies on agar media and synthesizes PHB depolymerase, but the “bald” mutant strain (bld4) forms shiny colonies and does not make the enzyme. The bld4 mutant could either have a defect in the promoter or coding regions of the PHB depolymerase gene (phaZ), or in a separate regulatory gene required for both morphogenesis and transcriptional activation of phaZ. Our goal was to assess the former possibility by amplifying phaZ from the bld4 mutant and the wild type using the polymerase chain reaction (PCR), visualizing PCR products by gel electrophoresis, and sequencing them. If any mutations are identified in the bld4 mutant, they might help us understand how synthesis of PHB depolymerase is regulated.

Recommended Citation

Young, Britney. “Identification of Mutations in the phaZ Gene of Bald Mutants of Streptomyces sp. SFB5A.” Junior Honors Projects, Bridgewater College, 2021.