Effect of surfactants and temperature on germination and vegetative growth of <i>Beauveria bassiana</i>

Mwamburi, Lizzy A.; Laing, Mark D.; Miller, Ray M.

doi:10.1590/S1517-838246120131077

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Brazilian Journal of Microbiology

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Environmental Microbiology • Braz. J. Microbiol. 46 (1) • Jan-Mar 2015 • https://doi.org/10.1590/S1517-838246120131077 copy

Effect of surfactants and temperature on germination and vegetative growth of Beauveria bassiana

Authorship SCIMAGO INSTITUTIONS RANKINGS

Three non-ionic surfactants: Tween20, Tween80 and Breakthru^® were screened for their effects on spore germination and mycelial growth rates and for their influence on three isolates of Beauveria bassianaspore germination at various temperatures. Tween20 and Tween80 were compatible with all the B. bassiana isolates in the germination studies, but inhibited germination at higher surfactant concentrations, irrespective of the conidial concentrations. Breakthru^® had an inhibitory effect on germination even at the lowest concentration of 0.1% on all the B. bassiana isolates. The effects of the surfactants on spore germination did not correspond with their effects on colony growth. Conidial viability within the same formulation declined significantly with increases in temperature, irrespective of the surfactant. The optimal temperature for conidial germination of B. bassiana isolates was approximately 25 °C with an upper limit at 30 °C. Isolate 7320 was identified as the least affected by the different surfactants. This isolate was able to germinate rapidly in a broad temperature range of 25–30 °C after 24 h, this characteristic being an essential factor in controlling house fly populations in poultry houses.

Beauveria bassiana ; surfactant; temperature; conidia germination; mycelial growth

Surfactant	Surfactant concentration (%)	Radial mycelial growth rate (K_r in mm day ⁻¹) ± se

		Isolates

		7320	7569	7771
Tween20	0	1.08 ± 0.08 ^f	1.46 ± 0.06 ^f	1.13 ± 0.08 ^b
	0.1	1.02 ± 0.07 ^def	1.17 ± 0.1 ^de	1.54 ± 0.3 ^c
	0.5	0.8 ± 0.09 ^ab	1.22 ± 0.17 ^e	1.11 ± 0.09 ^b
	1	0.9 ± 0.09 ^bcd	1.08 ± 0.13 ^cd	1.13 ± 0.09 ^b
	5	0.8 ± 0.09 ^ab	0.88 ± 0.09 ^b	1.10 ± 0.11 ^b
Tween80	0	1.08 ± 0.08^f	1.46 ± 0.06 ^f	1.13 ± 0.08 ^b
	0.1	0.96 ± 0.1^cdef	1.07 ± 0.13 ^c	1.07 ± 0.09 ^ab
	0.5	1.04 ± 0.12^def	1.12 ± 0.07^cd	1.05 ± 0.07 ^ab
	1	1.06 ± 0.12^ef	1.13 ± 0.1 ^cd	1.11 ± 0.09 ^a
	5	0.87 ± 0.1^bc	1.12 ± 0.13 ^cd	0.86 ± 0.15 ^ab
Breakthru^®	0	1.08 ± 0.08^f	1.46 ± 0.06 ^f	1.13 ± 0.08 ^b
	0.1	0.96 ± 0.12^cdef	1.26 ± 0.14 ^e	1.01 ± 0.09 ^ab
	0.5	1.04 ± 0.13^def	1.11 ± 0.13 ^cd	0.86 ± 0.1^ab
	1	0.92 ± 0.14^bcde	1.13 ± 0.13 ^cd	0.84 ± 0.08 ^ab
	5	0.69 ± 0.09^a	0.72 ± 0.1 ^a	0.68 ± 0.06 ^a
F-ratio		55.28	67.15	34.23
p-value		< 0.001	< 0.001	< 0.001
LSD		0.07	0.053	0.06
%CV		11.5	7	6.5
Effect		^ Significant at p ≤ 0.001.	^ Significant at p ≤ 0.001.	^ Significant at p ≤ 0.001.

Mean germination of conidia (%)

Isolates

		7320		7569		7771

Surfactant	Temperature	24 h	48 h	24 h	48 h	24 h	48 h
Water	25	98.4 ± 0.51 (1.46)^e	99.2 ± 0.37 (1.50)^a	61.0 ± 3.32 (0.90)^e	98.6 ± 0.51 (1.47)^a	63.8 ± 3.46 (0.93)^g	98.6 ± 0.51 (1.47)^a
	30	77.2 ± 0.86 (1.07)^d	98.4 ± 0.51 (1.46)^a	0.80 ± 0.12 (0.09)^d	98 ± 0.32 (1.43)^a	48.4 ± 1.08 (0.77)^d	98.4 ± 0.51 (1.46)^a
	35	0.18 ± 0.09 (0.04)^a	98.4 ± 0.40 (1.46)^a	0 ± 0 (0)^a	95.4 ± 1.44 (1.36)^a	0 ± 0 (0)^a	98.4 ± 0.51 (1.46)^a
Tween20	25	98.4 ± 0.51 (1.46)^e	98.6 ± 0.40 (1.47)^a	34.6 ± 1.86 (0.63)^d	98 ± 0.32 (1.43)^a	57.2 ± 3.65 (0.86)ⁱ	96.8 ± 1.77 (1.42)^a
	30	86.8 ± 1.07 (1.20)^cd	98.2 ± 0.37 (1.44)^a	27.8 ± 1.39(0.55)^de	97.4 ± 0.68 (1.41)^a	38.6 ± 2.73 (0.67)^de	95.6 ± 1.5 (1.37)^a
	35	0.04 ± 0.02 (0.01)^a	98.6 ± 0.40 (1.47)^a	0 ± 0 (0)^a	95.2 ± 1.39 (1.36)^a	0 ± 0 (0)^a	92.4 ± 2.18 (1.30)^a
Tween80	25	98.0 ± 0.95 (1.46)^e	98.8 ± 0.37 (1.47)^a	29.4 ± 3.14 (0.57)^f	97.8 ± 0.37 (1.42)^a	75.2 ± 1.59 (1.05)^h	98 ± 0.55 (1.44)^a
	30	83.0 ± 3.30 (1.15)^bc	98.2 ± 0.20 (1.44)^a	31.2 ± 1.85 (0.59)^b	95.2 ± 1.39 (1.36)^a	40 ± 3.54 (0.68)^f	98.8 ± 0.37 (1.47)^a
	35	0.04 ± 0.02 (0.01)^ab	98.2 ± 0.37 (1.44)^a	0 ± 0 (0)^a	95 ± 1.3 (1.35)^a	0 ± 0 (0)^a	98.8 ± 0.37 (1.47)^a
Breakthru^®	25	97.2 ± 0.86 (1.42)^e	98.6 ± 0.60 (1.48)^a	29.8 ± 1.77(0.58)^de	97.0 ± 0.32 (1.4)^a	21.6 ± 2.09 (0.48)^c	95.8 ± 1.59 (1.38)^a
	30	87.4 ± 2.50 (1.22)^bc	98.4 ± 0.51 (1.46)^a	7.0 ± 0.95 (0.27)^c	95.0 ± 1.38 (1.35)^a	15 ± 1.92 (0.39)^b	98.2 ± 0.37 (1.44)^a
	35	0 ± 0 (0)^ab	98.0 ± 0.32 (1.43)^a	0 ± 0 (0)^a	93.8 ± 1.02 (1.32)^a	0 ± 0 (0)^a	97.2 ± 0.73 (1.41)^a
F-ratio		2.52	0.29	104.68	0.41	30.15	1.35
p-value		0.034	0.941	< 0.001	0.868	< 0.001	0.255
LSD		0.081	0.072	0.053	0.068	0.067	0.093
%CV		7.2	3.9	12	3.8	10	5.1
Effect		^* * Significant at p < 0.05;	NS	^ Significant at p ≤ 0.001;	NS	^ Significant at p ≤ 0.001;	NS

Sociedade Brasileira de Microbiologia USP - ICB III - Dep. de Microbiologia, Sociedade Brasileira de Microbiologia, Av. Prof. Lineu Prestes, 2415, Cidade Universitária, 05508-900 São Paulo, SP - Brasil, Ramal USP 7979, Tel. / Fax: (55 11) 3813-9647 ou 3037-7095 - São Paulo - SP - Brazil
E-mail: bjm@sbmicrobiologia.org.br

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[1] Send correspondence to L.A. Mwamburi. School of Agricultural Sciences and Agribusiness, University of KwaZulu-Natal, 3209 Pietermaritzburg, South Africa. E-mail: lizzymwamburi@hotmail.com.