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Full Length Research Paper
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Analysis of
biofilm formation and associated gene detection in
Staphylococcus isolates from bovine mastitis
Li LI1,2, Hong-jun YANG1*,
Dai -cheng LIU2, Hong-bin HE1,
Chang-fa WANG1, Ji-feng ZHONG1,
Yun-dong GAO1 and
Yanjun Zeng3*
1Milch
Cow Research Center of Agricultural Science Academy of
Shandong Province, Jinan, Shandong 250100, P. R. China.
2College
of Life Science, Shandong Normal University, Jinan, Shandong
250014,
P. R. China.
3Beijing University of
Technology, 100 Pinglyuan, Chaoyang District, Beijing,
100124, P. R. China.
*Corresponding author. E-mail:
longfei1997@sina.com,
yjzeng@bjut.edu.cn.
Accepted 20 January, 2012 |
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Abstract |
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The objective of this study was to investigate the biofilm-forming
ability and distribution of biofilm
associated genes in clinically isolated
Staphylococcus in bovine mastitis. Silver staining,
scanning electron microscopy
(SEM) and
crystal violet staining were
conducted for the detection of biofilm-forming ability in
24-well plates. The bap, icaAD, icaBC,
Staphylococcal accessory regulator (sar),
accessory gene regulator (agr), sigB, clumping
factor A (clfA), clfB, fibronectin-binding
proteins (fnbpA) and fnbpB genes were
amplified by polymerase chain reaction (PCR). Formation of
biofilms was found macroscopically in 120 of the 137 strains
after being stained with silver (biofilm-forming rate
87.6%). Five strains did not adhere to
the surface of the silica gel after being stained with
crystal violet, while the remaining 132 strains did adhere.
Bap was amplified in 57 isolates, and
icaAD and icaBC were
isolated in 43 and 54 strains,
respectively. SigB, sar and agr
were amplified in 73, 49 and 38 isolates, respectively, and
clfA and clfB were isolated in 76 and 50
strains, respectively. FnbpA was present in 52
strains and fnbpB in 26 isolates. Our study reveals
that bap, sigB, sar, icaAD and
icaBC may be crucial biofilm
associated genes since these genes were present more often
in biofilm-positive strains than in
biofilm-negative strains. There was
no obvious difference between the frequencies of agr
in the biofilm-positive strains and
biofilm-negative strains, which indicates that the role
of agr in biofilm development is still
controversial. The distribution of
clfA, clfB, fnbpA and fnbpB
in biofilm-positive strains were
not greatly different from that in biofilm-negative strains.
Key words:
Bovine mastitis Staphylococcus,
biofilm, silver staining,
crystal violet staining. |
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