Abstract
Forty-three bacterial isolates in five genera were recovered from naturally infected green pepper fruits (38 samples) showing dark brown, irregular-shaped splotches. The pathogenicity test was performed on healthy green pepper fruits and red colonies were from inoculated fruits showing the same symptoms and the infected area developed into soft rot. Their identification was based on phenotypic characters and sequence of the gene fragment coding 16S rRNA. Of 43 isolates, 10 showing splotches on green pepper fruits belonged to genus
Serratia
on the basis of phenotypic characters. One representative isolate of the genus
Serratia
has been identified by partial 16S rRNA gene sequencing and phylogenetic analysis as belonging to the
Serratia rubidaea
and has the potential to cause spot on green pepper. Eleven phytopathogenic bacterial isolates were also obtained at the same time but did not induce any splotch symptoms on artificially infected green pepper. Five out of 11 bacterial isolates were identified as
Ralstonia
on the basis of biochemical tests. Partial sequencing of 16S ribosomal gene of representative isolate revealed that the isolate is
Ralstonia solanacearum
. The six remaining isolates were related to
Xanthomonas vesicatoria
on the basis of biochemical tests. Twenty-two of opportunistic human pathogens were isolated at the same time and related to
Proteus
and
Klebsiella
. Opportunistic human pathogens did not produce any symptoms on artificially infected green pepper. One representative isolate for each genus was identified as
Klebsiella oxytoca
and
Proteus mirabilis
based on their partial 16S rRNA gene sequences. The virulence of the
S. rubidaea,
the causal agent of green pepper fruits splotches was attributed to the production and secretion of a large variety of enzymes capable of degrading the complex polysaccharides of the plant cell wall and membrane constituents.