Pectic Enzyme Activities of Bacteria Associated with Rotted Onions ( Allium cepa )

Abstract

The aerobic bacteria associated with soft rot in onions (Allium cepa) were isolated and identified as a Vibrio sp., Micrococcus epidermidis, Pseudomonas cepacia, an Acinetobacter sp., a Xanthomonas sp., Bacillus polymyxa, and Bacillus megaterium. With the cup-plate assay method, no pectin hydrolase could be detected from any of these isolates when they were cultured in pectin medium, but lyase and pectinesterases were detectable. Onion tissue cultures showed pectin hydrolase activity for P. cepacia and B. polymyxa and lyase and pectinesterase activities for all of the isolates, usually at higher levels of activity than those of the pectin medium culture filtrates. In both culture media, Vibrio sp. showed the highest lyase and pectinesterase activities. In the viscometric test, all of the isolates achieved at least a 50% decrease in viscosity for lyase enzyme, with M. epidermidis and Vibrio sp. recording viscosity decreases as high as 83%. The ability to cause soft rot in onion bulbs was demonstrated by P. cepacia and Xanthomonas sp. Benzoic acid at a concentration of 0.8 mg/ml caused total suppression of enzyme production, whereas sodium benzoate at this concentration reduced pectinesterase production by 71% and lyase production by 72%. The possible use of these preservatives in the control of soft rot in onions is noted.

Extracellular Production of Pectinase from Bacteria Isolated from Rotten Apples from Lahore, Pakistan

“…Patil and Dayanand (2006) reported that the pectinase produced by Pseudomonas fluorescens led to the soft rot of potato tubes and also reported the production of pectinase by Pseudomonas cepacia in diseased onions [13]. P. aeruginosa, isolated from tannery waste polluted soil, has the ability to produce pectinases, phosphatases, cellulases and proteases [26]. However, in our investigation, P. aeruginosa showed the highest pectinolytic activity as compared to the other four strains.…”

Isolation and characterization of onion degrading bacteria from onion waste produced in South Buenos Aires province, Argentina

“…Conversely, P. poae RE*1-1-14 has only been reported as an endophytic bacterium from sugar beet (Mu ¨ller et al 2013). To our knowledge, only B. megaterium and B. subtilis have previously been described in association with onion (Obi and Umezurike 1981;Zaid et al 2012).…”

“…It has been proved that a commercial product containing strains from genera Bacillus and Pseudomonas enhances methanogenesis and odor control in anaerobic digestion (Duran et al 2006). In addition, strain MB2-62 and VE-74 could potentially be used as a biocontrol agent for onion phytopathogens, like Rhizoctonia solani, Fusarium oxysporum and Sclerotium cepivorum, as antagonistic activity against these fungi has been reported for different B. subtilis strains and for P. poae strain RE*1-1-14 (Asaka and Shoda 1996;Mu ¨ller et al 2013;Obi and Umezurike 1981;Phae et al 1990;Utkhede and Rahe 1983).…”

Novel non-destructive quality assessment techniques of onion bulbs: a comparative study

“…The major constituents of an onion are water, protein, and carbohydrates (Brewster 2008). It has been reported that pectic enzymes are involved in the degradation of pectic constituents of cell walls, which is caused by pathogenic microorganisms that are related to several onion diseases, including bacterial soft rot (Obi and Umezurike 1981). Additionally, Botrytis cinerea, one of the pathogenic microorganisms responsible for onion diseases, has been reported to produce pectic degrading enzymes (Aboaba 2009).…”