The aim of this study was to investigate the toxicity level of chromium and glutaraldehyde. This research was conducted by testing the resistance level of fungi (Aspergillus niger sp.) toward glutaraldehyde and chromium in the medium of Potato Dextrose Agar (PDA). Variable of this experiment was the growth of Aspergillus niger sp. that indicates the resistance level of Aspergillus niger sp. The growth rate of Aspergillus niger sp. was classified on four scales. They were, (I) scale 1: zero growth; (II) scale 2: low growth (+); (III) scale 3: medium growth (++); (IV) Scale: 4 high growth (+++). All collected data were analysed by One Way ANOVA. The result showed that the toxicity of chromium and glutaraldehyde tanning material were highly significantly different toward Aspergillus niger (P<0,01). The Aspergillus niger sp. growth rate scale in chromium medium was high (scale 4: 4.00±0.00). Meanwhile, the growth rate scale of the Aspergillus niger sp. in glutaraldehyde medium was low (scale 2: 1.33 ± 0.58). Based on the fungi growth rate, it can be concluded that glutaraldehyde was more toxic than chromium tanning material toward Aspergillus niger sp. Furthermore, it can be said that glutaraldehyde is not quite ideal to be used as an alternative of chromium as a tanning material.

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Leathers, which are made from natural fibers, can serve as media for microorganisms to grow. The currently used antimicrobial agents or biocides in the leather industry are harmful to human health and the environment. Therefore, the use of antimicrobial agents should be restricted. This study aims at developing eco-friendly biocides that could substitute for toxic chemicals as it will be tested on vegetable-tanned leather. Due to their large surface area and ability to retain moisture, the vegetable tanned leather has a higher possibility of biodeterioration than other types of leathers tanned by mineral tanning agents. In this work, the natural biopolymer of chitosan was chosen for its ability to inhibit the bacterial growth. The results showed that chitosan coating by impregnation method in drum using chitosan/leather ratio of 1% in formic acid for 2 hours is successfully achieved the bacterial growth inhibition.

Restrictions and control on the use of fatliquor especially the sulphited oil during leather production is required due to its effect on chromium change valence (from Cr(III) to Cr(VI)). Utilization of the other oil sources such as vegetable or mineral oil is worthed to be a substitute material. The aim of this study is to quantify the potential release of Cr(III) and Cr(VI) from different fatliquors and find the alternative fatliquor. The results showed that the use of 10% mineral oil and sulphited oil affected the Cr total and formation Cr(VI) in the leather, while using 6% condensed tannin (Mimosa) as an antioxidant is effective to reduce the Cr total and Cr(VI) contents in the leather.

The abundant hydroxyl groups (-OH) of vegetable tanned leather enhances the bacterial growth possibility. In this work, antibacterial vegetable tanned leather was developed taking advantage of chitosan antibacterial activity. Different chitosan utilization method was conducted, namely drum impregnation and spraying. Antibacterial testing was carried out using agar diffusion method to identify the effect of chitosan against Gram-positive bacteria (Staphylococcus aureus). The results showed that the use of 1% (w/v) chitosan by spraying method tends to be more effective in improving the antibacterial properties of vegetable tanned leather. While, the leather sample of drum impregnation at initial pH 4 has the lowest antibacterial activity among others. The results of FTIR analysis showed that there was no significant difference between control and chitosan modified tanned leather, confirming the similar functional groups between it.