Comparison of the growth kinetics and proteolytic activities of Chryseobacterium species and Pseudomonas fluorescens

Abstract

The effect of temperature on the growth kinetics and proteolytic activity of Chryseobacterium joostei and Chryseobacterium bovis was determined during this study. The results were compared with the activities of Pseudomonas fluorescens, which is regarded to be a major food spoilage psychrotolerant microorganism. For the growth studies, cultures were incubated in nutrient broth in a temperature gradient incubator (from 9 to 50 °C) and separately at 4 °C, and the optical density was measured at different time intervals. Growth temperature profiles for each organism were constructed. For determination of proteolytic activity, the cultures were incubated in fat-free ultra-high temperature processed milk in the temperature gradient incubator for 72 h (temperature range as above). Cell-free extracts were used to determine the proteolytic activity using the azocasein method. Results of the growth studies showed that C. joostei had the ability to grow over a wider temperature range than C. bovis and P. fluorescens without being affected by changes in the temperature. For the proteolytic activity, C. joostei had significantly (p < 0.001) higher activity per milligram of protein at 15.5 °C, followed by C. bovis and P. fluorescens. The results showed that C. joostei potentially has an even greater spoilage capacity in milk on the basis of growth rate and proteolytic activity than did P. fluorescens.

Spoilage potential of psychrotrophic bacteria isolated from raw milk and the thermo-stability of their enzymes

“…This might be explained by horizontal gene transfer from proteolytic species or phenotypic variation among isolates. Chryseobacterium also appears as a dominant member of raw milk microbiota (Yuan et al, 2017) and some species show a greater spoilage ability than P. fluorescens based on their proteolytic and lipolytic activity (Bekker et al, 2015(Bekker et al, , 2016. In this study, species of Chryseobacterium showed more proteolytic than lipolytic activity, and C. oncorhynchi showed higher proteolytic activity than many isolates of Pseudomonas.…”

The Biodiversity of the Microbiota Producing Heat-Resistant Enzymes Responsible for Spoilage in Processed Bovine Milk and Dairy Products

“…Although some studies have detected hydrolytic strains of Acinetobacter in raw milk samples ( Nörnberg et al, 2010 ; von Neubeck et al, 2015 ; Vithanage et al, 2016 ), the heat resistance of these enzymes and the spoilage potential from this genus is not well characterized and requires further investigation. Chryseobacterium (previously classified in Flavobacterium ) also appears as a dominant member of Algerian cold raw milk ( Table 2 ) and some species like Chryseobacterium joostei have been described recently as showing an even greater spoilage capacity than P. fluorescens in milk on the basis of growth rate, proteolytic and lipolytic activity ( Bekker et al, 2015 , 2016 ). However, besides proteolytic enzymes being resistant to pasteurization, resistance of these enzymes to UHT is not known.…”

Spoilage of tilapia by Pseudomonas putida with different adhesion abilities

“…The spoilage ability of spoilage bacteria is related to the activity of protease and growth ability( Bekker et al, 2015 , Shao et al, 2021 ). Our study found that strains with similar spoilage ability on fish fillets have different spoilage potential in vivo due to their adhesion and colonization ability.…”