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Purpose The purpose of this study is to measure the impact of commitment in corporate social responsibility (CSR) in its various forms (CSR philanthropy/ altruism, CSR integration and CSR innovation) on the financial performance as measured by certain ratios. Design/methodology/approach Thus, on the basis of a theoretically constructed questionnaire administered to 82 responsibles (general managers, human resources managers and CSR responsibles) operating in four business areas, the authors have developed the extent of the overall CSR commitment and the extent of commitment by CSR action type. Findings The examination of the impact of the CSR commitment on the financial performance has partially approved the social impact assumption. Indeed, only the positive effect of CSR philanthropy is demonstrated. Otherwise, for integrated and innovative actions, the low involvement in these actions in relation to philanthropic ones could explain the lack of significant association. But this result is also important, as it marks the lack of any negative effects. Even if they do not result in a better financial performance, these commitments do not bring harm to the firm. As for the strategic approach predominance on the altruistic approach, this hypothesis is checked only in the case of firms operating in the chemical sector. Research limitations/implications The main limitation of the study is the limited size of the total sample and the sample by industry, so the authors expect a larger sample might be able to provide more meaningful results. Practical implications Then, the study suggests the importance of implementing real CSR strategies for firms that often find doubt and ambiguity when they decide to undertake social actions. However, these results do not mean that companies must refrain from driving altruistic or philanthropic activities but are encouraged to seek a social performance that suits a certain level of integration and innovation. Social implications The most important of all the above is that the negative impact of social actions is not verified in any way, allowing to state that the social actions do not exert a negative effect on the financial performance. So, participation in social problems do not bring harm to the firm. Originality/value The originality of this work comes from: the measure of CSR commitment, and the use of a classification typology of CSR actions in terms of their interaction with the core of the firm’s business as developed by Halme (2009). In fact, based on a theoretically constructed questionnaire, the authors have developed two measures of responsible commitment (level of commitment and intensity of commitment) of some industrial Tunisian firms.

Microalgae as feedstock for biofuel production have attracted serious consideration as an important sustainable source of energy. For biodiesel production with microalgae, a series of consecutive processes should be performed as selection of adequate microalgal strains, mass culture, cell harvesting, oil extraction and transesterification. The aim of this study was to investigate the growth and lipid accumulation of a new isolated marine microalgal strain by optimizing culture medium composition and applying different stressful culture conditions. Microalga CTM 20023 was isolated from the evaporating salt-ponds at Sfax, Tunisia, using serial-dilution technique from enriched cultures. Phylogenetic analysis based on SSU rDNA and rbcL-3P sequences attributed this isolate to a new species of the Amphora genus. This wild strain possesses rapid gravity sedimentation of 2.91 m h(-1), suitable for an easy and low-cost biomass harvest. The optimization of the composition of the culture medium through statistical experimental designs improved the specific growth rate of Amphora sp. from 0.149 to 0.262 day(-1) and increased its 15-day culture biomass production from 465 to 2200 mg L(-1) (dw) and its lipid content from 140 to 370 mg g(-1) (dw). Highest biomass productivity of 178 mg L(-1) day(-1) was achieved at the 10th day of culture. Highest lipid content of 530 mg g(-1) (dw) was obtained under phosphorus starvation and 64.34% of these lipids were saturated fatty acids. A first growth stage, in optimized condition, would thus offer the maximum productivity for an algal biomass feed stream, followed by second stressful stage for lipid accumulation, thus suitable for biodiesel production.